Kubernetes executor

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Use the Kubernetes executor to use Kubernetes clusters for your builds. The executor calls the Kubernetes cluster API and creates a pod for each GitLab CI job.

The Kubernetes executor divides the build into multiple steps:

  1. Prepare: Create the Pod against the Kubernetes Cluster. This creates the containers required for the build and services to run.
  2. Pre-build: Clone, restore cache, and download artifacts from previous stages. This step runs on a special container as part of the pod.
  3. Build: User build.
  4. Post-build: Create cache, upload artifacts to GitLab. This step also uses the special container as part of the pod.

How the runner creates Kubernetes pods

The following diagram shows the interaction between a GitLab instance and a runner hosted on a Kubernetes cluster. The runner calls the Kubernetes API to create pods on the cluster.

The pod consists of the following containers for each service defined in the .gitlab-ci.yml or config.toml files:

  • A build container defined as build.
  • A helper container defined as helper.
  • A services containers defined as svc-X, where X is [0-9]+.

Services and containers run in the same Kubernetes pod and share the same localhost address. The following restrictions apply:

  • In GitLab Runner 12.8 and Kubernetes 1.7 and later, the services are accessible through their DNS names. If you use an older version, you must use localhost.
  • You cannot use several services that use the same port. For example, you cannot have two mysql services at the same time.
sequenceDiagram participant G as GitLab instance participant R as Runner on Kubernetes cluster participant Kube as Kubernetes API participant P as POD R->>+G: Get a CI job. loop G-->R: ; end Note over R,G: POST /api/v4/jobs/request G->>+R: CI job data. R-->>-Kube: Create a POD to run the CI job. Note over R,Kube: POST to Kube API P->>+P: Execute job. Note over P: CI build job = Prepare + Pre-build + Build + Post-build P->>+G: Job logs

The interaction in the diagram is valid for any Kubernetes cluster. For example, turnkey solutions hosted on the major public cloud providers, or self-managed Kubernetes installations.

Connect to the Kubernetes API

Use the following options to connect to the Kubernetes API. The user account provided must have permission to create, list, and attach to Pods in the specified namespace.

Option Description
host Optional Kubernetes apiserver host URL (auto-discovery attempted if not specified).
cert_file Optional Kubernetes apiserver user auth certificate.
key_file Optional Kubernetes apiserver user auth private key.
ca_file Optional Kubernetes apiserver ca certificate.

If you’re running GitLab Runner in the Kubernetes cluster, you should omit all of these fields so that the GitLab Runner auto-discovers the Kubernetes API.

If you’re running GitLab Runner externally to the Cluster, then you must set each of these settings and ensure that GitLab Runner has access to the Kubernetes API on the cluster.

Set the bearer token for Kubernetes API calls

To set the bearer token for API calls to create pods, use the KUBERNETES_BEARER_TOKEN variable. This allows project owners to use project secret variables to specify a bearer token.

When specifying the bearer token, you must set the Host configuration setting.

variables:
  KUBERNETES_BEARER_TOKEN: thebearertokenfromanothernamespace

Configure runner API permissions

To configure permissions for the core API group, update the values.yml file for GitLab Runner Helm charts.

You can either:

  • Set rbac.create to true.
  • Specify a service account rbac.serviceAccountName: <service_account_name> with the following permissions in the values.yml file.

Resource Verb (Optional Feature Flags)
events list (FF_RETRIEVE_POD_WARNING_EVENTS=true), watch (FF_PRINT_POD_EVENTS=true)
namespaces create, delete
pods attach (FF_USE_LEGACY_KUBERNETES_EXECUTION_STRATEGY=false), create, delete, exec, get
pods/logs get (FF_USE_LEGACY_KUBERNETES_EXECUTION_STRATEGY=false), list (FF_USE_LEGACY_KUBERNETES_EXECUTION_STRATEGY=false)
secrets create, delete, get, update
serviceAccounts get
services create, get
  • The serviceAccount permission is needed only:

    • For GitLab 15.0 and 15.1.
    • For GitLab 15.0.1, 15.1.1, and 15.2 when resource_availability_check_max_attempts is set to a value higher than 0.
  • As of GitLab Runner 15.8 the configmaps permission is no longer needed.

  • The event permission is needed only:

    • For GitLab 16.2.1 and later.
  • The namespace permission is needed only:

    • When enabling namespace isolation via namespace_per_job.

Configuration settings

Use the following settings in the config.toml file to configure the Kubernetes executor.

CPU requests and limits

Setting Description
cpu_limit The CPU allocation given to build containers.
cpu_limit_overwrite_max_allowed The maximum amount that the CPU allocation can be written to for build containers. When empty, it disables the cpu limit overwrite feature.
cpu_request The CPU allocation requested for build containers.
cpu_request_overwrite_max_allowed The maximum amount that the CPU allocation request can be written to for build containers. When empty, it disables the cpu request overwrite feature.
helper_cpu_limit The CPU allocation given to build helper containers.
helper_cpu_limit_overwrite_max_allowed The maximum amount that the CPU allocation can be written to for helper containers. When empty, it disables the cpu limit overwrite feature.
helper_cpu_request The CPU allocation requested for build helper containers.
helper_cpu_request_overwrite_max_allowed The maximum amount that the CPU allocation request can be written to for helper containers. When empty, it disables the cpu request overwrite feature.
service_cpu_limit The CPU allocation given to build service containers.
service_cpu_limit_overwrite_max_allowed The maximum amount that the CPU allocation can be written to for service containers. When empty, it disables the cpu limit overwrite feature.
service_cpu_request The CPU allocation requested for build service containers.
service_cpu_request_overwrite_max_allowed The maximum amount that the CPU allocation request can be written to for service containers. When empty, it disables the cpu request overwrite feature.

Memory requests and limits

Setting Description
memory_limit The amount of memory allocated to build containers.
memory_limit_overwrite_max_allowed The maximum amount that the memory allocation can be written to for build containers. When empty, it disables the memory limit overwrite feature.
memory_request The amount of memory requested from build containers.
memory_request_overwrite_max_allowed The maximum amount that the memory allocation request can be written to for build containers. When empty, it disables the memory request overwrite feature.
helper_memory_limit The amount of memory allocated to build helper containers.
helper_memory_limit_overwrite_max_allowed The maximum amount that the memory allocation can be written to for helper containers. When empty, it disables the memory limit overwrite feature.
helper_memory_request The amount of memory requested for build helper containers.
helper_memory_request_overwrite_max_allowed The maximum amount that the memory allocation request can be written to for helper containers. When empty, it disables the memory request overwrite feature.
service_memory_limit The amount of memory allocated to build service containers.
service_memory_limit_overwrite_max_allowed The maximum amount that the memory allocation can be written to for service containers. When empty, it disables the memory limit overwrite feature.
service_memory_request The amount of memory requested for build service containers.
service_memory_request_overwrite_max_allowed The maximum amount that the memory allocation request can be written to for service containers. When empty, it disables the memory request overwrite feature.

Storage requests and limits

Setting Description
ephemeral_storage_limit The ephemeral storage limit for build containers.
ephemeral_storage_limit_overwrite_max_allowed The maximum amount that the ephemeral storage limit for build containers can be overwritten. When empty, it disables the ephemeral storage limit overwrite feature.
ephemeral_storage_request The ephemeral storage request given to build containers.
ephemeral_storage_request_overwrite_max_allowed The maximum amount that the ephemeral storage request can be overwritten by for build containers. When empty, it disables the ephemeral storage request overwrite feature.
helper_ephemeral_storage_limit The ephemeral storage limit given to helper containers.
helper_ephemeral_storage_limit_overwrite_max_allowed The maximum amount that the ephemeral storage limit can be overwritten by for helper containers. When empty, it disables the ephemeral storage request overwrite feature.
helper_ephemeral_storage_request The ephemeral storage request given to helper containers.
helper_ephemeral_storage_request_overwrite_max_allowed The maximum amount that the ephemeral storage request can be overwritten by for helper containers. When empty, it disables the ephemeral storage request overwrite feature.
service_ephemeral_storage_limit The ephemeral storage limit given to service containers.
service_ephemeral_storage_limit_overwrite_max_allowed The maximum amount that the ephemeral storage limit can be overwritten by for service containers. When empty, it disables the ephemeral storage request overwrite feature.
service_ephemeral_storage_request The ephemeral storage request given to service containers.
service_ephemeral_storage_request_overwrite_max_allowed The maximum amount that the ephemeral storage request can be overwritten by for service containers. When empty, it disables the ephemeral storage request overwrite feature.

Other config.toml settings

Setting Description
affinity Specify affinity rules that determine which node runs the build. Read more about using affinity.
allow_privilege_escalation Run all containers with the allowPrivilegeEscalation flag enabled. When empty, it does not define the allowPrivilegeEscalation flag in the container SecurityContext and allows Kubernetes to use the default privilege escalation behavior.
allowed_images Wildcard list of images that can be specified in .gitlab-ci.yml. If not present all images are allowed (equivalent to ["*/*:*"]). View details.
allowed_pull_policies List of pull policies that can be specified in the .gitlab-ci.yml file or the config.toml file.
allowed_services Wildcard list of services that can be specified in .gitlab-ci.yml. If not present all images are allowed (equivalent to ["*/*:*"]). View details.
automount_service_account_token Boolean to control the automount of the service account token in the build pod.
bearer_token Default bearer token used to launch build pods.
bearer_token_overwrite_allowed Boolean to allow projects to specify a bearer token that will be used to create the build pod.
build_container_security_context Sets a container security context for the build container. Read more about security context.
cap_add Specify Linux capabilities that should be added to the job pod containers. Read more about capabilities configuration in Kubernetes executor.
cap_drop Specify Linux capabilities that should be dropped from the job pod containers. Read more about capabilities configuration in Kubernetes executor.
cleanup_grace_period_seconds When a job completes, the duration in seconds that the pod has to terminate gracefully. After this period, the processes are forcibly halted with a kill signal. Ignored if terminationGracePeriodSeconds is specified.
dns_policy Specify the DNS policy that should be used when constructing the pod: none, default, cluster-first, cluster-first-with-host-net. The Kubernetes default (cluster-first) is used if not set.
dns_config Specify the DNS configuration that should be used when constructing the pod. Read more about using pod’s DNS config.
helper_container_security_context Sets a container security context for the helper container. Read more about security context.
helper_image (Advanced) Override the default helper image used to clone repos and upload artifacts.
helper_image_flavor Sets the helper image flavor (alpine, alpine3.16, alpine3.17, alpine3.18, alpine3.19, or ubuntu). Defaults to alpine. Using alpine is the same as alpine3.18.
host_aliases List of additional host name aliases that will be added to all containers. Read more about using extra host aliases.
image_pull_secrets An array of items containing the Kubernetes docker-registry secret names used to authenticate Docker image pulling from private registries.
init_permissions_container_security_context Sets a container security context for the init-permissions container. Read more about security context.
namespace Namespace in which to run Kubernetes Pods.
namespace_per_job Isolate jobs in separate namespaces. If enabled, namespace and namespace_overwrite_allowed are ignored.
namespace_overwrite_allowed Regular expression to validate the contents of the namespace overwrite environment variable (documented below). When empty, it disables the namespace overwrite feature.
node_selector A table of key=value pairs in the format of string=string (string:string in the case of environment variables). Setting this limits the creation of pods to Kubernetes nodes matching all the key=value pairs. Read more about using node selectors.
node_tolerations A table of "key=value" = "Effect" pairs in the format of string=string:string. Setting this allows pods to schedule to nodes with all or a subset of tolerated taints. Only one toleration can be supplied through environment variable configuration. The key, value, and effect match with the corresponding field names in Kubernetes pod toleration configuration.
pod_annotations A table of key=value pairs in the format of string=string. This is the list of annotations to be added to each build pod created by the Runner. The value of these can include environment variables for expansion. Pod annotations can be overwritten in each build.
pod_annotations_overwrite_allowed Regular expression to validate the contents of the pod annotations overwrite environment variable. When empty, it disables the pod annotations overwrite feature.
pod_labels A table of key=value pairs in the format of string=string. This is the list of labels to be added to each build pod created by the runner. The value of these can include environment variables for expansion. Pod labels can be overwritten in each build by using pod_labels_overwrite_allowed.
pod_labels_overwrite_allowed Regular expression to validate the contents of the pod labels overwrite environment variable. When empty, it disables the pod labels overwrite feature.
pod_security_context Configured through the configuration file, this sets a pod security context for the build pod. Read more about security context.
pod_termination_grace_period_seconds Pod-level setting which determines the duration in seconds which the pod has to terminate gracefully. After this, the processes are forcibly halted with a kill signal. Ignored if terminationGracePeriodSeconds is specified.
poll_interval How frequently, in seconds, the runner will poll the Kubernetes pod it has just created to check its status (default = 3).
poll_timeout The amount of time, in seconds, that needs to pass before the runner will time out attempting to connect to the container it has just created. Useful for queueing more builds that the cluster can handle at a time (default = 180).
cleanup_resources_timeout The total amount of time for Kubernetes resources to be cleaned up after the job completes. Supported syntax: 1h30m, 300s, 10m. Default is 5 minutes (5m).
priority_class_name Specify the Priority Class to be set to the pod. The default one is used if not set.
privileged Run containers with the privileged flag.
pull_policy Specify the image pull policy: never, if-not-present, always. If not set, the cluster’s image default pull policy is used. For more information and instructions on how to set multiple pull policies, see using pull policies. See also if-not-present, never security considerations. You can also restrict pull policies.
resource_availability_check_max_attempts The maximum number of attempts to check if a resource (service account and/or pull secret) set is available before giving up. There is 5 seconds interval between each attempt. Introduced in GitLab 15.0. Read more about resources check during prepare step.
runtime_class_name A Runtime class to use for all created pods. If the feature is unsupported by the cluster, jobs exit or fail.
service_container_security_context Sets a container security context for the service containers. Read more about security context.
scheduler_name Scheduler to use for scheduling build pods.
service_account Default service account job/executor pods use to talk to Kubernetes API.
service_account_overwrite_allowed Regular expression to validate the contents of the service account overwrite environment variable. When empty, it disables the service account overwrite feature.
services List of services attached to the build container using the sidecar pattern. Read more about using services.
use_service_account_image_pull_secrets When enabled, the pod created by the executor lacks imagePullSecrets. This causes the pod to be created using the imagePullSecrets from the service account, if set.
terminationGracePeriodSeconds Duration after the processes running in the pod are sent a termination signal and the time when the processes are forcibly halted with a kill signal. Deprecated in favour of cleanup_grace_period_seconds and pod_termination_grace_period_seconds.
volumes Configured through the configuration file, the list of volumes that is mounted in the build container. Read more about using volumes.
pod_spec This setting is an experiment. Overwrites the pod specification generated by the runner manager with a list of configurations set on the pod used to run the CI Job. All the properties listed Kubernetes Pod Specification can be set. For more information, see Overwrite generated pod specifications (experiment).
retry_limit The maximum number of attempts to communicate with Kubernetes API. The retry interval between each attempt is based on a backoff algorithm starting at 500 ms.
retry_backoff_max Custom maximum backoff value in milliseconds for the retry interval to reach for each attempt. The default value is 2000 ms and it can not be lower than 500 ms. The default maximum retry interval to reach for each attempt is 2 seconds and can be customized with retry_backoff_max.
retry_limits How many times each request error is to be retried.

Configuration example

The following sample shows an example configuration of the config.toml file for the Kubernetes executor.

concurrent = 4

[[runners]]
  name = "myRunner"
  url = "https://gitlab.com/ci"
  token = "......"
  executor = "kubernetes"
  [runners.kubernetes]
    host = "https://45.67.34.123:4892"
    cert_file = "/etc/ssl/kubernetes/api.crt"
    key_file = "/etc/ssl/kubernetes/api.key"
    ca_file = "/etc/ssl/kubernetes/ca.crt"
    namespace = "gitlab"
    namespace_overwrite_allowed = "ci-.*"
    bearer_token_overwrite_allowed = true
    privileged = true
    cpu_limit = "1"
    memory_limit = "1Gi"
    service_cpu_limit = "1"
    service_memory_limit = "1Gi"
    helper_cpu_limit = "500m"
    helper_memory_limit = "100Mi"
    poll_interval = 5
    poll_timeout = 3600
    dns_policy = "cluster-first"
    priority_class_name = "priority-1"
    [runners.kubernetes.node_selector]
      gitlab = "true"
    [runners.kubernetes.node_tolerations]
      "node-role.kubernetes.io/master" = "NoSchedule"
      "custom.toleration=value" = "NoSchedule"
      "empty.value=" = "PreferNoSchedule"
      "onlyKey" = ""

Configure the executor service account

To configure the executor service account, you can set the KUBERNETES_SERVICE_ACCOUNT environment variable or use the --kubernetes-service-account flag.

Pods and containers

You can configure pods and containers to control how jobs are executed.

Default annotations for job pods

History

The following annotations are added by default on the Pod running the jobs:

Key Description
job.runner.gitlab.com/id The ID of the job, unique across all jobs in the GitLab instance.
job.runner.gitlab.com/url The URL for the job details.
job.runner.gitlab.com/sha The commit revision the project is built for.
job.runner.gitlab.com/before_sha The previous latest commit present on a branch or tag.
job.runner.gitlab.com/ref The branch or tag name for which the project is built.
job.runner.gitlab.com/name The name of the job.
project.runner.gitlab.com/id The project ID of the job.

To overwrite default annotations, use the pod_annotations in the GitLab Runner configuration. You can also overwrite annotations for each CI/CD job in the .gitlab-ci.yml file.

Pod lifecycle

A pod’s lifecycle can be affected by:

  • Setting the pod_termination_grace_period_seconds property in the TOML configuration file. The process running on the pod can run for the given duration after the TERM signal is sent. A kill signal is sent if the Pod is not successfully terminated after this period of time.
  • Enabling the FF_USE_POD_ACTIVE_DEADLINE_SECONDS feature flag. When enabled and the job times out, the pod running the CI/CD job is marked as failed and all associated containers are killed. To have the job time out on GitLab first, activeDeadlineSeconds is set to configured timeout + 1 second.
note
If both the FF_USE_POD_ACTIVE_DEADLINE_SECONDS feature flag is enabled and the pod_termination_grace_period_seconds is set with a non zero value, the CI job pod is not immediately terminated when the job times out. The pod terminationGracePeriods ensures the pod is terminated only when it expired.

Overwrite pod tolerations

To overwrite Kubernetes pod tolerations:

  1. In the config.toml or Helm values.yaml file, to enable the overwrite of CI job pod tolerations, define a regular expression for node_tolerations_overwrite_allowed. This regular expression validates the values of CI variable names that start with KUBERNETES_NODE_TOLERATIONS_.

    runners:
     ...
     config: |
       [[runners]]
         [runners.kubernetes]
           node_tolerations_overwrite_allowed = ".*"
    
  2. In the .gitlab-ci.yml file, define one or more CI variables to overwrite CI job pod tolerations.

    variables:
      KUBERNETES_NODE_TOLERATIONS_1: 'node-role.kubernetes.io/master:NoSchedule'
      KUBERNETES_NODE_TOLERATIONS_2: 'custom.toleration=value:NoSchedule'
      KUBERNETES_NODE_TOLERATIONS_3: 'empty.value=:PreferNoSchedule'
      KUBERNETES_NODE_TOLERATIONS_4: 'onlyKey'
      KUBERNETES_NODE_TOLERATIONS_5: '' # tolerate all taints
    

Overwrite pod labels

To overwrite Kubernetes pod labels for each CI/CD job:

  1. In the .config.yaml file, define a regular expression for pod_labels_overwrite_allowed.
  2. In the .gitlab-ci.yml file, set the KUBERNETES_POD_LABELS_* variables with values of key=value. The pod labels are overwritten to the key=value. You can apply multiple values:

     variables:
       KUBERNETES_POD_LABELS_1: "Key1=Val1"
       KUBERNETES_POD_LABELS_2: "Key2=Val2"
       KUBERNETES_POD_LABELS_3: "Key3=Val3"
    

Overwrite pod annotations

To overwrite Kubernetes pod annotations for each CI/CD job:

  1. In the .config.yaml file, define a regular expression for pod_annotations_overwrite_allowed.
  2. In the .gitlab-ci.yml file, set the KUBERNETES_POD_ANNOTATIONS_* variables and use key=value for the value. Pod annotations are overwritten to the key=value. You can specify multiple annotations:

    variables:
      KUBERNETES_POD_ANNOTATIONS_1: "Key1=Val1"
      KUBERNETES_POD_ANNOTATIONS_2: "Key2=Val2"
      KUBERNETES_POD_ANNOTATIONS_3: "Key3=Val3"
    

In the example below, the pod_annotations and the pod_annotations_overwrite_allowed are set. This configuration allows overwrite of any of the pod_annotations configured in the config.toml.

[[runners]]
  # usual configuration
  executor = "kubernetes"
  [runners.kubernetes]
    image = "alpine"
    pod_annotations_overwrite_allowed = "*"
    [runners.kubernetes.pod_annotations]
      "Key1" = "Val1"
      "Key2" = "Val2"
      "Key3" = "Val3"
      "Key4" = "Val4"

Overwrite generated pod specifications

Status: Beta
History

This feature is in beta. We strongly recommend that you use this feature on a test Kubernetes cluster before you use it on a production cluster. To use this feature, you must enable the FF_USE_ADVANCED_POD_SPEC_CONFIGURATION feature flag.

To add feedback for improvements before the feature is made generally available, use this issue.

To modify the PodSpec generated by the runner manager, use the pod_spec setting in the config.toml file.

The pod_spec setting:

  • Overwrites and completes fields for the generated pod specification.
  • Overwrites configuration values that might have been set in your config.toml under [runners.kubernetes].

You can configure multiple pod_spec settings.

Setting Description
name Name given to the custom pod_spec.
patch_path Path to the file that defines the changes to apply to the final PodSpec object before it is generated. The file must be a JSON or YAML file.
patch A JSON or YAML format string that describes the changes which must be applied to the final PodSpec object before it is generated.
patch_type The strategy the runner uses to apply the specified changes to the PodSpec object generated by GitLab Runner. The accepted values are merge, json, and strategic.

You cannot set the patch_path and patch in the same pod_spec configuration, otherwise an error occurs.

Example of multiple pod_spec configurations in the config.toml:

[[runners]]
  [runners.kubernetes]
    [[runners.kubernetes.pod_spec]]
      name = "hostname"
      patch = '''
        hostname: "custom-pod-hostname"
      '''
      patch_type = "merge"
    [[runners.kubernetes.pod_spec]]
      name = "subdomain"
      patch = '''
        subdomain: "subdomain"
      '''
      patch_type = "strategic"
    [[runners.kubernetes.pod_spec]]
      name = "terminationGracePeriodSeconds"
      patch = '''
        [{"op": "replace", "path": "/terminationGracePeriodSeconds", "value": 60}]
      '''
      patch_type = "json"

Merge patch strategy

The merge patch strategy applies a key-value replacement on the existing PodSpec. If you use this strategy, the pod_spec configuration in the config.toml overwrites the values in the final PodSpec object before it is generated. Because the values are completely overwritten, you should use this patch strategy with caution.

Example of a pod_spec configuration with the merge patch strategy:

concurrent = 1
check_interval = 1
log_level = "debug"
shutdown_timeout = 0

[session_server]
  session_timeout = 1800

[[runners]]
  name = ""
  url = "https://gitlab.example.com"
  id = 0
  token = "__REDACTED__"
  token_obtained_at = 0001-01-01T00:00:00Z
  token_expires_at = 0001-01-01T00:00:00Z
  executor = "kubernetes"
  shell = "bash"
  environment = ["FF_USE_ADVANCED_POD_SPEC_CONFIGURATION=true", "CUSTOM_VAR=value"]
  [runners.kubernetes]
    image = "alpine"
    ...
    [[runners.kubernetes.pod_spec]]
      name = "build envvars"
      patch = '''
        containers:
        - env:
          - name: env1
            value: "value1"
          - name: env2
            value: "value2"
          name: build
      '''
      patch_type = "merge"

With this configuration, the final PodSpec has only one container called build with two environment variables env1 and env2. The example above make the related CI Job failed as:

  • The helper container specification is removed.
  • The build container specification lost all necessary configuration set by GitLab Runner.

To prevent the job from failing, in this example, the pod_spec must contain the untouched properties generated by GitLab Runner.

JSON patch strategy

The json patch strategy uses the JSON Patch specification to give control over the PodSpec objects and arrays to update. You cannot use this strategy on array properties.

Example of a pod_spec configuration with the json patch strategy. In this configuration, a new key: value pair is added to the existing nodeSelector. The existing values are not overwritten.

concurrent = 1
check_interval = 1
log_level = "debug"
shutdown_timeout = 0

[session_server]
  session_timeout = 1800

[[runners]]
  name = ""
  url = "https://gitlab.example.com"
  id = 0
  token = "__REDACTED__"
  token_obtained_at = 0001-01-01T00:00:00Z
  token_expires_at = 0001-01-01T00:00:00Z
  executor = "kubernetes"
  shell = "bash"
  environment = ["FF_USE_ADVANCED_POD_SPEC_CONFIGURATION=true", "CUSTOM_VAR=value"]
  [runners.kubernetes]
    image = "alpine"
    ...
    [[runners.kubernetes.pod_spec]]
      name = "val1 node"
      patch = '''
        { "op": "add", "path": "/nodeSelector", "value": { key1: "val1" } }
      '''
      patch_type = "json"

Strategic patch strategy

This strategic patch strategy uses the existing patchStrategy applied to each field of the PodSpec object.

Example of a pod_spec configuration with the strategic patch strategy. In this configuration, a resource request is set to on the build container.

concurrent = 1
check_interval = 1
log_level = "debug"
shutdown_timeout = 0

[session_server]
  session_timeout = 1800

[[runners]]
  name = ""
  url = "https://gitlab.example.com"
  id = 0
  token = "__REDACTED__"
  token_obtained_at = 0001-01-01T00:00:00Z
  token_expires_at = 0001-01-01T00:00:00Z
  executor = "kubernetes"
  shell = "bash"
  environment = ["FF_USE_ADVANCED_POD_SPEC_CONFIGURATION=true", "CUSTOM_VAR=value"]
  [runners.kubernetes]
    image = "alpine"
    ...
    [[runners.kubernetes.pod_spec]]
      name = "cpu request 500m"
      patch = '''
        containers:
        - name: build
          resources:
            requests:
              cpu: "500m"
      '''
      patch_type = "strategic"

With this configuration, a resource request is set to on the build container.

Best practices

  • Test the added pod_spec in a test environment before deployment in a production environment.
  • Make sure that the pod_spec configuration does not negatively impact the GitLab Runner generated specification.
  • Do not use the merge patch strategy for complex pod specification updates.
  • Where possible, use the config.toml when the configuration is available. For example, the following configuration replaces the first environment variables set by GitLab Runner by the one set in the custom pod_spec instead of adding the environment variable set to the existing list.
concurrent = 1
check_interval = 1
log_level = "debug"
shutdown_timeout = 0

[session_server]
  session_timeout = 1800

[[runners]]
  name = ""
  url = "https://gitlab.example.com"
  id = 0
  token = "__REDACTED__"
  token_obtained_at = 0001-01-01T00:00:00Z
  token_expires_at = 0001-01-01T00:00:00Z
  executor = "kubernetes"
  shell = "bash"
  environment = ["FF_USE_ADVANCED_POD_SPEC_CONFIGURATION=true", "CUSTOM_VAR=value"]
  [runners.kubernetes]
    image = "alpine"
    ...
    [[runners.kubernetes.pod_spec]]
      name = "build envvars"
      patch = '''
        containers:
        - env:
          - name: env1
            value: "value1"
          name: build
      '''
      patch_type = "strategic"

Create a PVC for each build job by modifying the Pod Spec

To create a PersistentVolumeClaim for each build job make sure to check out how to enable the Pod Spec functionality.

Kubernetes allows to create an ephemeral PersistentVolumeClaim attached to the lifecycle of a Pod. This will work if dynamic provisioning is enabled on your Kubernetes cluster allowing each PVC to request a new Volume, the volume too will be tied to the lifetime of the Pod.

After dynamic provisioning is enabled, the config.toml can be modified as follows to create an ephemeral PVC:

[[runners.kubernetes.pod_spec]]
  name = "ephemeral-pvc"
  patch = '''
    containers:
    - name: build
      volumeMounts:
      - name: builds
        mountPath: /builds
    - name: helper
      volumeMounts:
      - name: builds
        mountPath: /builds
    volumes:
    - name: builds
      ephemeral:
        volumeClaimTemplate:
          spec:
            storageClassName: <The Storage Class that will dynamically provision a Volume>
            accessModes: [ ReadWriteOnce ]
            resources:
              requests:
                storage: 1Gi
  '''

Set a security policy for the pod

Configure the security context in the config.toml to set a security policy for the build pod.

Use the following options:

Option Type Required Description
fs_group int No A special supplemental group that applies to all containers in a pod.
run_as_group int No The GID to run the entry point of the container process.
run_as_non_root boolean No Indicates that the container must run as a non-root user.
run_as_user int No The UID to run the entry point of the container process.
supplemental_groups int list No A list of groups applied to the first process run in each container, in addition to the container’s primary GID.
selinux_type string No The SELinux type label that applies to all containers in a pod.

Example of a pod security context in the config.toml:

concurrent = %(concurrent)s
check_interval = 30
  [[runners]]
    name = "myRunner"
    url = "gitlab.example.com"
    executor = "kubernetes"
    [runners.kubernetes]
      helper_image = "gitlab-registry.example.com/helper:latest"
      [runners.kubernetes.pod_security_context]
        run_as_non_root = true
        run_as_user = 59417
        run_as_group = 59417
        fs_group = 59417

Remove old runner pods

History

Sometimes old runner pods are not cleared. This can happen when the runner manager is incorrectly shut down.

To handle this situation, you can use the GitLab Runner Pod Cleanup application to schedule cleanup of old pods. For more information, see:

Set a security policy for the container

History

Configure the container security context in the config.toml executor to set a container security policy for the build, helper, or service pods.

Use the following options:

Option Type Required Description
run_as_group int No The GID to run the entry point of the container process.
run_as_non_root boolean No Indicates that the container must run as a non-root user.
run_as_user int No The UID to run the entry point of the container process.
capabilities.add string list No The capabilities to add when running the container.
capabilities.drop string list No The capabilities to drop when running the container.
selinux_type string No The SELinux type label that is associated with the container process.

In the following example in the config.toml, the security context configuration:

  • Sets a pod security context.
  • Overrides run_as_user and run_as_group for the build and helper containers.
  • Specifies that all service containers inherit run_as_user and run_as_group from the pod security context.
concurrent = 4
check_interval = 30
  [[runners]]
    name = "myRunner"
    url = "gitlab.example.com"
    executor = "kubernetes"
    [runners.kubernetes]
      helper_image = "gitlab-registry.example.com/helper:latest"
      [runners.kubernetes.pod_security_context]
        run_as_non_root = true
        run_as_user = 59417
        run_as_group = 59417
        fs_group = 59417
      [runners.kubernetes.init_permissions_container_security_context]
        run_as_user = 1000
        run_as_group = 1000
      [runners.kubernetes.build_container_security_context]
        run_as_user = 65534
        run_as_group = 65534
        [runners.kubernetes.build_container_security_context.capabilities]
          add = ["NET_ADMIN"]
      [runners.kubernetes.helper_container_security_context]
        run_as_user = 1000
        run_as_group = 1000
      [runners.kubernetes.service_container_security_context]
        run_as_user = 1000
        run_as_group = 1000

Set a pull policy

Use the pull_policy parameter in the config.toml file to specify a single or multiple pull policies. The policy controls how an image is fetched and updated, and applies to the build image, helper image, and any services.

To determine which policy to use, see the Kubernetes documentation about pull policies.

For a single pull policy:

[runners.kubernetes]
  pull_policy = "never"

For multiple pull policies:

[runners.kubernetes]
  # use multiple pull policies
  pull_policy = ["always", "if-not-present"]

When you define multiple policies, each policy is attempted until the image is obtained successfully. For example, when you use [ always, if-not-present ], the policy if-not-present is used if the always policy fails due to a temporary registry problem.

To retry a failed pull:

[runners.kubernetes]
  pull_policy = ["always", "always"]

The GitLab naming convention is different to the Kubernetes one.

Runner pull policy Kubernetes pull policy Description
blank blank Uses the default policy, as specified by Kubernetes.
if-not-present IfNotPresent The image is pulled only if it is not already present on the node that executes the job. There are security considerations you should be aware of.
always Always The image is pulled every time the job is executed.
never Never The image is never pulled and requires the node to already have it.

Specify container capabilities

You can specify the Kubernetes capabilities to use in the container.

To specify the container capabilities, use the cap_add and cap_drop options in the config.toml. Container runtimes can also define a default list of capabilities, like those in Docker or the container.

There is a list of capabilities that the runner drops by default. Capabilities that you list in cap_add option are excluded from being dropped.

Example configuration in the config.toml file:

concurrent = 1
check_interval = 30
[[runners]]
  name = "myRunner"
  url = "gitlab.example.com"
  executor = "kubernetes"
  [runners.kubernetes]
    # ...
    cap_add = ["SYS_TIME", "IPC_LOCK"]
    cap_drop = ["SYS_ADMIN"]
    # ...

When you specify the capabilities:

  • User-defined cap_drop has priority over user-defined cap_add. If you define the same capability in both settings, only the capability from cap_drop is passed to the container.

  • Remove the CAP_ prefix from capability identifiers passed to the container configuration. For example, if you want to add or drop the CAP_SYS_TIME capability, in the configuration file, enter the string, SYS_TIME.

  • The owner of the Kubernetes cluster can define a PodSecurityPolicy, where specific capabilities are allowed, restricted, or added by default. These rules take precedence over any user-defined configuration.

Overwrite container resources

You can overwrite Kubernetes CPU and memory allocations for each CI/CD job. You can apply settings for requests and limits for the build, helper, and service containers.

To overwrite container resources, use the following variables in the .gitlab-ci.yml file.

The values for the variables are restricted to the maximum overwrite setting for that resource. If the maximum overwrite has not been set for a resource, the variable is not used.

 variables:
   KUBERNETES_CPU_REQUEST: "3"
   KUBERNETES_CPU_LIMIT: "5"
   KUBERNETES_MEMORY_REQUEST: "2Gi"
   KUBERNETES_MEMORY_LIMIT: "4Gi"
   KUBERNETES_EPHEMERAL_STORAGE_REQUEST: "512Mi"
   KUBERNETES_EPHEMERAL_STORAGE_LIMIT: "1Gi"

   KUBERNETES_HELPER_CPU_REQUEST: "3"
   KUBERNETES_HELPER_CPU_LIMIT: "5"
   KUBERNETES_HELPER_MEMORY_REQUEST: "2Gi"
   KUBERNETES_HELPER_MEMORY_LIMIT: "4Gi"
   KUBERNETES_HELPER_EPHEMERAL_STORAGE_REQUEST: "512Mi"
   KUBERNETES_HELPER_EPHEMERAL_STORAGE_LIMIT: "1Gi"

   KUBERNETES_SERVICE_CPU_REQUEST: "3"
   KUBERNETES_SERVICE_CPU_LIMIT: "5"
   KUBERNETES_SERVICE_MEMORY_REQUEST: "2Gi"
   KUBERNETES_SERVICE_MEMORY_LIMIT: "4Gi"
   KUBERNETES_SERVICE_EPHEMERAL_STORAGE_REQUEST: "512Mi"
   KUBERNETES_SERVICE_EPHEMERAL_STORAGE_LIMIT: "1Gi"

Define a list of services

History

Define a list of services in the config.toml.

concurrent = 1
check_interval = 30
  [[runners]]
    name = "myRunner"
    url = "gitlab.example.com"
    executor = "kubernetes"
    [runners.kubernetes]
      helper_image = "gitlab-registy.example.com/helper:latest"
      [[runners.kubernetes.services]]
        name = "postgres:12-alpine"
        alias = "db1"
      [[runners.kubernetes.services]]
        name = "registry.example.com/svc1"
        alias = "svc1"
        entrypoint = ["entrypoint.sh"]
        command = ["executable","param1","param2"]
        environment = ["ENV=value1", "ENV2=value2"]

If the service environment includes HEALTHCHECK_TCP_PORT, GitLab Runner waits until the service responds on that port before starting user CI scripts. You can also configure the HEALTHCHECK_TCP_PORT environment variable in a services section of .gitlab-ci.yml.

Overwrite service containers resources

If a job has multiple service containers, you can set explicit resource requests and limits to each service container. Use the variables attribute in each service to overwrite container resources specified in .gitlab-ci.yml.

  services:
    - name: redis:5
      alias: redis5
      variables:
        KUBERNETES_SERVICE_CPU_REQUEST: "3"
        KUBERNETES_SERVICE_CPU_LIMIT: "6"
        KUBERNETES_SERVICE_MEMORY_REQUEST: "3Gi"
        KUBERNETES_SERVICE_MEMORY_LIMIT: "6Gi"
        KUBERNETES_EPHEMERAL_STORAGE_REQUEST: "2Gi"
        KUBERNETES_EPHEMERAL_STORAGE_LIMIT: "3Gi"
    - name: postgres:12
      alias: MY_relational-database.12
      variables:
        KUBERNETES_CPU_REQUEST: "2"
        KUBERNETES_CPU_LIMIT: "4"
        KUBERNETES_MEMORY_REQUEST: "1Gi"
        KUBERNETES_MEMORY_LIMIT: "2Gi"
        KUBERNETES_EPHEMERAL_STORAGE_REQUEST: "1Gi"
        KUBERNETES_EPHEMERAL_STORAGE_LIMIT: "2Gi"

These specific settings take precedence over the general settings for the job. The values are still restricted to the maximum overwrite setting for that resource.

Overwrite the Kubernetes default service account

To overwrite the Kubernetes service account for each CI/CD job in the .gitlab-ci.yml file, set the variable KUBERNETES_SERVICE_ACCOUNT_OVERWRITE.

You can use this variable to specify a service account attached to the namespace, which you may need for complex RBAC configurations.

variables:
  KUBERNETES_SERVICE_ACCOUNT_OVERWRITE: ci-service-account

To ensure only designated service accounts are used during CI runs, define a regular expression for either:

  • The service_account_overwrite_allowed setting.
  • The KUBERNETES_SERVICE_ACCOUNT_OVERWRITE_ALLOWED environment variable.

If you don’t set either, the overwrite is disabled.

Set the RuntimeClass

History

Use runtime_class_name to set the RuntimeClass for each job container.

If you specify a RuntimeClass name and it’s not configured in the cluster or the feature is not supported, the executor fails to create jobs.

concurrent = 1
check_interval = 30
  [[runners]]
    name = "myRunner"
    url = "gitlab.example.com"
    executor = "kubernetes"
    [runners.kubernetes]
      runtime_class_name = "myclass"

Nodes

Define a list of node affinities

Define a list of node affinities to add to a pod specification at build time.

Example configuration in the config.toml:

concurrent = 1
[[runners]]
  name = "myRunner"
  url = "gitlab.example.com"
  executor = "kubernetes"
  [runners.kubernetes]
    [runners.kubernetes.affinity]
      [runners.kubernetes.affinity.node_affinity]
        [[runners.kubernetes.affinity.node_affinity.preferred_during_scheduling_ignored_during_execution]]
          weight = 100
          [runners.kubernetes.affinity.node_affinity.preferred_during_scheduling_ignored_during_execution.preference]
            [[runners.kubernetes.affinity.node_affinity.preferred_during_scheduling_ignored_during_execution.preference.match_expressions]]
              key = "cpu_speed"
              operator = "In"
              values = ["fast"]
            [[runners.kubernetes.affinity.node_affinity.preferred_during_scheduling_ignored_during_execution.preference.match_expressions]]
              key = "mem_speed"
              operator = "In"
              values = ["fast"]
        [[runners.kubernetes.affinity.node_affinity.preferred_during_scheduling_ignored_during_execution]]
          weight = 50
          [runners.kubernetes.affinity.node_affinity.preferred_during_scheduling_ignored_during_execution.preference]
            [[runners.kubernetes.affinity.node_affinity.preferred_during_scheduling_ignored_during_execution.preference.match_expressions]]
              key = "core_count"
              operator = "In"
              values = ["high", "32"]
            [[runners.kubernetes.affinity.node_affinity.preferred_during_scheduling_ignored_during_execution.preference.match_fields]]
              key = "cpu_type"
              operator = "In"
              values = ["arm64"]
      [runners.kubernetes.affinity.node_affinity.required_during_scheduling_ignored_during_execution]
        [[runners.kubernetes.affinity.node_affinity.required_during_scheduling_ignored_during_execution.node_selector_terms]]
          [[runners.kubernetes.affinity.node_affinity.required_during_scheduling_ignored_during_execution.node_selector_terms.match_expressions]]
            key = "kubernetes.io/e2e-az-name"
            operator = "In"
            values = [
              "e2e-az1",
              "e2e-az2"
            ]

Define nodes where pods are scheduled

History

Use pod affinity and anti-affinity to constrain the nodes your pod is eligible to be scheduled on, based on labels on other pods.

Example configuration in the config.toml:

concurrent = 1
[[runners]]
  name = "myRunner"
  url = "gitlab.example.com"
  executor = "kubernetes"
  [runners.kubernetes]
    [runners.kubernetes.affinity]
      [runners.kubernetes.affinity.pod_affinity]
        [[runners.kubernetes.affinity.pod_affinity.required_during_scheduling_ignored_during_execution]]
          topology_key = "failure-domain.beta.kubernetes.io/zone"
          namespaces = ["namespace_1", "namespace_2"]
          [runners.kubernetes.affinity.pod_affinity.required_during_scheduling_ignored_during_execution.label_selector]
            [[runners.kubernetes.affinity.pod_affinity.required_during_scheduling_ignored_during_execution.label_selector.match_expressions]]
              key = "security"
              operator = "In"
              values = ["S1"]
        [[runners.kubernetes.affinity.pod_affinity.preferred_during_scheduling_ignored_during_execution]]
        weight = 100
        [runners.kubernetes.affinity.pod_affinity.preferred_during_scheduling_ignored_during_execution.pod_affinity_term]
          topology_key = "failure-domain.beta.kubernetes.io/zone"
          [runners.kubernetes.affinity.pod_affinity.preferred_during_scheduling_ignored_during_execution.pod_affinity_term.label_selector]
            [[runners.kubernetes.affinity.pod_affinity.preferred_during_scheduling_ignored_during_execution.pod_affinity_term.label_selector.match_expressions]]
              key = "security_2"
              operator = "In"
              values = ["S2"]
      [runners.kubernetes.affinity.pod_anti_affinity]
        [[runners.kubernetes.affinity.pod_anti_affinity.required_during_scheduling_ignored_during_execution]]
          topology_key = "failure-domain.beta.kubernetes.io/zone"
          namespaces = ["namespace_1", "namespace_2"]
          [runners.kubernetes.affinity.pod_anti_affinity.required_during_scheduling_ignored_during_execution.label_selector]
            [[runners.kubernetes.affinity.pod_anti_affinity.required_during_scheduling_ignored_during_execution.label_selector.match_expressions]]
              key = "security"
              operator = "In"
              values = ["S1"]
          [runners.kubernetes.affinity.pod_anti_affinity.required_during_scheduling_ignored_during_execution.namespace_selector]
            [[runners.kubernetes.affinity.pod_anti_affinity.required_during_scheduling_ignored_during_execution.namespace_selector.match_expressions]]
              key = "security"
              operator = "In"
              values = ["S1"]
        [[runners.kubernetes.affinity.pod_anti_affinity.preferred_during_scheduling_ignored_during_execution]]
        weight = 100
        [runners.kubernetes.affinity.pod_anti_affinity.preferred_during_scheduling_ignored_during_execution.pod_affinity_term]
          topology_key = "failure-domain.beta.kubernetes.io/zone"
          [runners.kubernetes.affinity.pod_anti_affinity.preferred_during_scheduling_ignored_during_execution.pod_affinity_term.label_selector]
            [[runners.kubernetes.affinity.pod_anti_affinity.preferred_during_scheduling_ignored_during_execution.pod_affinity_term.label_selector.match_expressions]]
              key = "security_2"
              operator = "In"
              values = ["S2"]
          [runners.kubernetes.affinity.pod_anti_affinity.preferred_during_scheduling_ignored_during_execution.pod_affinity_term.namespace_selector]
            [[runners.kubernetes.affinity.pod_anti_affinity.preferred_during_scheduling_ignored_during_execution.pod_affinity_term.namespace_selector.match_expressions]]
              key = "security_2"
              operator = "In"
              values = ["S2"]

Overwrite the node selector

To overwrite the node selector:

  1. In the config.toml or Helm values.yaml file, enable overwriting of the node selector:

    runners:
     ...
     config: |
       [[runners]]
         [runners.kubernetes]
           node_selector_overwrite_allowed = ".*"
    
  2. In the .gitlab-ci.yml file, define the variable to overwrite the node selector:

    variables:
      KUBERNETES_NODE_SELECTOR_* = ''
    

In the following example, to overwrite the Kubernetes node architecture, the settings are configured in the config.toml and .gitlab-ci.yml:

config.toml
concurrent = 1
check_interval = 1
log_level = "debug"
shutdown_timeout = 0

listen_address = ':9252'

[session_server]
  session_timeout = 1800

[[runners]]
  name = ""
  url = "https://gitlab.com/"
  id = 0
  token = "__REDACTED__"
  token_obtained_at = "0001-01-01T00:00:00Z"
  token_expires_at = "0001-01-01T00:00:00Z"
  executor = "kubernetes"
  shell = "bash"
  [runners.kubernetes]
    host = ""
    bearer_token_overwrite_allowed = false
    image = "alpine"
    namespace = ""
    namespace_overwrite_allowed = ""
    pod_labels_overwrite_allowed = ""
    service_account_overwrite_allowed = ""
    pod_annotations_overwrite_allowed = ""
    node_selector_overwrite_allowed = "kubernetes.io/arch=.*" # <--- allows overwrite of the architecture
.gitlab-ci.yml
  job:
    image: IMAGE_NAME
    variables:
      KUBERNETES_NODE_SELECTOR_ARCH: 'kubernetes.io/arch=amd64' # <--- select the right architecture

Specify the node to execute builds

Use the node_selector option to specify which node in a Kubernetes cluster to execute builds on. It is a table of key=value pairs in the format of string=string (string:string in the case of environment variables).

The runner uses the information provided to determine the OS and architecture for the build. This ensures that the correct helper image is used. By default, the OS and architecture is assumed to be linux/amd64.

You can use specific labels to schedule nodes with different operating systems and architectures.

Example for linux/arm64

  [[runners]]
    name = "myRunner"
    url = "gitlab.example.com"
    executor = "kubernetes"

    [runners.kubernetes.node_selector]
      "kubernetes.io/arch" = "arm64"
      "kubernetes.io/os" = "linux"

Example for windows/amd64

Kubernetes for Windows has certain limitations, so if process isolation is used, you must also provide the specific windows build version with the node.kubernetes.io/windows-build label.

  [[runners]]
    name = "myRunner"
    url = "gitlab.example.com"
    executor = "kubernetes"

    # The FF_USE_POWERSHELL_PATH_RESOLVER feature flag has to be enabled for PowerShell
    # to resolve paths for Windows correctly when Runner is operating in a Linux environment
    # but targeting Windows nodes.
    environment = ["FF_USE_POWERSHELL_PATH_RESOLVER=true"]

    [runners.kubernetes.node_selector]
      "kubernetes.io/arch" = "amd64"
      "kubernetes.io/os" = "windows"
      "node.kubernetes.io/windows-build" = "10.0.20348"

Networking

Configure a container lifecycle hook

History

Use container lifecycle hooks to run code configured for a handler when the corresponding lifecycle hook is executed.

You can configure two types of hooks: PreStop and PostStart. Each of them allows only one type of handler to be set.

Example configuration in the config.toml file:

[[runners]]
  name = "kubernetes"
  url = "https://gitlab.example.com/"
  executor = "kubernetes"
  token = "yrnZW46BrtBFqM7xDzE7dddd"
  [runners.kubernetes]
    image = "alpine:3.11"
    privileged = true
    namespace = "default"
    [runners.kubernetes.container_lifecycle.post_start.exec]
      command = ["touch", "/builds/postStart.txt"]
    [runners.kubernetes.container_lifecycle.pre_stop.http_get]
      port = 8080
      host = "localhost"
      path = "/test"
      [[runners.kubernetes.container_lifecycle.pre_stop.http_get.http_headers]]
        name = "header_name_1"
        value = "header_value_1"
      [[runners.kubernetes.container_lifecycle.pre_stop.http_get.http_headers]]
        name = "header_name_2"
        value = "header_value_2"

Use the following settings to configure each lifecycle hook:

Option Type Required Description
exec KubernetesLifecycleExecAction No Exec specifies the action to take.
http_get KubernetesLifecycleHTTPGet No HTTPGet specifies the http request to perform.
tcp_socket KubernetesLifecycleTcpSocket No TCPsocket specifies an action involving a TCP port.

KubernetesLifecycleExecAction

Option Type Required Description
command string list Yes The command line to execute inside the container.

KubernetesLifecycleHTTPGet

Option Type Required Description
port int Yes The number of the port to access on the container.
host string No The host name to connect to, defaults to the pod IP (optional).
path string No The path to access on the HTTP server (optional).
scheme string No The scheme used for connecting to the host. Defaults to HTTP (optional).
http_headers KubernetesLifecycleHTTPGetHeader list No Custom headers to set in the request (optional).

KubernetesLifecycleHTTPGetHeader

Option Type Required Description
name string Yes HTTP header name.
value string Yes HTTP header value.

KubernetesLifecycleTcpSocket

Option Type Required Description
port int Yes The number of the port to access on the container.
host string No The host name to connect to, defaults to the pod IP (optional).

Configure pod DNS settings

Use the following options to configure the DNS settings of the pods.

Option Type Required Description
nameservers string list No A list of IP addresses that will be used as DNS servers for the pod.
options KubernetesDNSConfigOption No A optional list of objects where each object may have a name property (required) and a value property (optional).
searches string lists No A list of DNS search domains for hostname lookup in the pod.

Example configuration in the config.toml file:

concurrent = 1
check_interval = 30
[[runners]]
  name = "myRunner"
  url = "https://gitlab.example.com"
  token = "__REDACTED__"
  executor = "kubernetes"
  [runners.kubernetes]
    image = "alpine:latest"
    [runners.kubernetes.dns_config]
      nameservers = [
        "1.2.3.4",
      ]
      searches = [
        "ns1.svc.cluster-domain.example",
        "my.dns.search.suffix",
      ]

      [[runners.kubernetes.dns_config.options]]
        name = "ndots"
        value = "2"

      [[runners.kubernetes.dns_config.options]]
        name = "edns0"

KubernetesDNSConfigOption

Option Type Required Description
name string Yes Configuration option name.
value *string No Configuration option value.

Default list of dropped capabilities

GitLab Runner drops the following capabilities by default.

User-defined cap_add has priority over the default list of dropped capabilities. If you want to add the capability that is dropped by default, add it to cap_add.

  • NET_RAW

Add extra host aliases

This feature is available in Kubernetes 1.7 and higher.

Configure a host aliases to instruct Kubernetes to add entries to /etc/hosts file in the container.

Use the following options:

Option Type Required Description
IP string Yes The IP address you want to attach hosts to.
Hostnames string list Yes A list of host name aliases that will be attached to the IP.

Example configuration in the config.toml file:

concurrent = 4

[[runners]]
  # usual configuration
  executor = "kubernetes"
  [runners.kubernetes]
    [[runners.kubernetes.host_aliases]]
      ip = "127.0.0.1"
      hostnames = ["web1", "web2"]
    [[runners.kubernetes.host_aliases]]
      ip = "192.168.1.1"
      hostnames = ["web14", "web15"]

You can also configure host aliases by using the command-line parameter --kubernetes-host_aliases with JSON input. For example:

gitlab-runner register --kubernetes-host_aliases '[{"ip":"192.168.1.100","hostnames":["myservice.local"]},{"ip":"192.168.1.101","hostnames":["otherservice.local"]}]'

Volumes

Using the cache with the Kubernetes executor

When the cache is used with the Kubernetes executor, a volume called /cache is mounted on the pod. During job execution, if cached data is needed, the runner checks if cached data is available. Cached data is available if a compressed file is available on the cache volume.

To set the cache volume, use the cache_dir setting in the config.toml file.

  • If available, the compressed file is extracted into the build folder and can then be used in the job.
  • If not available, the cached data is downloaded from the configured storage and saved into the cache dir as a compressed file. The compressed file is then extracted into the build folder.

Configure volume types

You can mount the following volume types:

  • hostPath
  • persistentVolumeClaim
  • configMap
  • secret
  • emptyDir
  • csi

Example of a configuration with multiple volume types:

concurrent = 4

[[runners]]
  # usual configuration
  executor = "kubernetes"
  [runners.kubernetes]
    [[runners.kubernetes.volumes.host_path]]
      name = "hostpath-1"
      mount_path = "/path/to/mount/point"
      read_only = true
      host_path = "/path/on/host"
    [[runners.kubernetes.volumes.host_path]]
      name = "hostpath-2"
      mount_path = "/path/to/mount/point_2"
      read_only = true
    [[runners.kubernetes.volumes.pvc]]
      name = "pvc-1"
      mount_path = "/path/to/mount/point1"
    [[runners.kubernetes.volumes.config_map]]
      name = "config-map-1"
      mount_path = "/path/to/directory"
      [runners.kubernetes.volumes.config_map.items]
        "key_1" = "relative/path/to/key_1_file"
        "key_2" = "key_2"
    [[runners.kubernetes.volumes.secret]]
      name = "secrets"
      mount_path = "/path/to/directory1"
      read_only = true
      [runners.kubernetes.volumes.secret.items]
        "secret_1" = "relative/path/to/secret_1_file"
    [[runners.kubernetes.volumes.empty_dir]]
      name = "empty-dir"
      mount_path = "/path/to/empty_dir"
      medium = "Memory"
    [[runners.kubernetes.volumes.csi]]
      name = "csi-volume"
      mount_path = "/path/to/csi/volume"
      driver = "my-csi-driver"
      [runners.kubernetes.volumes.csi.volume_attributes]
        size = "2Gi"

hostPath volume

Configure the hostPath volume to instruct Kubernetes to mount a specified host path in the container.

Use the following options in the config.toml file:

Option Type Required Description
name string Yes The name of the volume.
mount_path string Yes Path inside of the container where the volume is mounted.
sub_path string No Mount a sub-path in the volume instead of the root.
host_path string No Host path to mount as the volume. If not specified, then this is set to the same path as mount_path.
read_only boolean No Sets the volume in read-only mode (defaults to false).

persistentVolumeClaim volume

Configure the persistentVolumeClaim volume to instruct Kubernetes to use a persistentVolumeClaim defined in a Kubernetes cluster and mount it in the container.

Use the following options in the config.toml file:

Option Type Required Description
name string Yes The name of the volume and at the same time the name of PersistentVolumeClaim that should be used. Supports variables. For more information, see Persistent per-concurrency build volumes.
mount_path string Yes Path in the container where the volume is mounted.
read_only boolean No Sets the volume to read-only mode (defaults to false).
sub_path string No Mount a sub-path in the volume instead of the root.

configMap volume

Configure the configMap volume to instruct Kubernetes to use a configMap defined in a Kubernetes cluster and mount it in the container.

Use the following options in the config.toml:

Option Type Required Description
name string Yes The name of the volume and at the same time the name of configMap that should be used.
mount_path string Yes Path in the container where the volume is mounted.
read_only boolean No Sets the volume to read-only mode (defaults to false).
sub_path string No Mount a sub-path in the volume instead of the root.
items map[string]string no Key-to-path mapping for keys from the configMap that should be used.

Each key from the configMap is changed into a file and stored in the mount path. By default:

  • All keys are included.
  • The configMap key is used as the filename.
  • The value is stored in the file contents.

To change the default key and value storage, use the items option . If you use the items option, only specified keys are added to the volumes and all other keys are skipped.

note
If you use a key that doesn’t exist, the job fails on the pod creation stage.

secret volume

Configure a secret volume to instruct Kubernetes to use a secret defined in a Kubernetes cluster and mount it in the container.

Use the following options in the config.toml file:

Option Type Required Description
name string Yes The name of the volume and at the same time the name of secret that should be used.
mount_path string Yes Path inside of container where the volume should be mounted.
read_only boolean No Sets the volume in read-only mode (defaults to false).
sub_path string No Mount a sub-path within the volume instead of the root.
items map[string]string No Key-to-path mapping for keys from the configMap that should be used.

Each key from selected secret is changed into a file stored in the selected mount path. By default:

  • All keys are included.
  • The configMap key is used as the filename.
  • The value is stored in the file contents.

To change default key and value storage, use the items option. If you use the items option, only specified keys are added to the volumes and all other keys are skipped.

note
If you use a key that doesn’t exist, the job fails on the pod creation stage.

emptyDir volume

Configure an emptyDir volume to instruct Kubernetes to mount an empty directory in the container.

Use the following options in the config.toml file:

Option Type Required Description
name string Yes The name of the volume.
mount_path string Yes Path inside of container where the volume should be mounted.
sub_path string No Mount a sub-path in the volume instead of the root.
medium string No “Memory” provides a tmpfs, otherwise it defaults to the node disk storage (defaults to “”).
size_limit string No The total amount of local storage required for the emptyDir volume.

csi volume

Configure a Container Storage Interface (csi) volume to instruct Kubernetes to use a custom csi driver to mount an arbitrary storage system in the container.

Use the following options in the config.toml:

Option Type Required Description
name string Yes The name of the volume.
mount_path string Yes Path inside of container where the volume should be mounted.
driver string Yes A string value that specifies the name of the volume driver to use.
fs_type string No A string value that specifies the name of the file system type (Ex. “ext4”, “xfs”, “ntfs”.).
volume_attributes map[string]string No Key-value pair mapping for attributes of the CSI volume.
sub_path string No Mount a sub-path within the volume instead of the root.
read_only boolean No Sets the volume in read-only mode (defaults to false).

Mount volumes on service containers

Volumes defined for the build container are also automatically mounted for all services containers. You can use this functionality as an alternative to services_tmpfs (available only to Docker executor), to mount database storage in RAM to speed up tests.

Example configuration in the config.toml file:

[[runners]]
  # usual configuration
  executor = "kubernetes"
  [runners.kubernetes]
    [[runners.kubernetes.volumes.empty_dir]]
      name = "mysql-tmpfs"
      mount_path = "/var/lib/mysql"
      medium = "Memory"

Custom volume mount

To store the builds directory for the job, define custom volume mounts to the configured builds_dir (/builds by default). If you use PVC volumes, based on the access mode, you might be limited to running jobs on one node.

Example configuration in the config.toml file:

concurrent = 4

[[runners]]
  # usual configuration
  executor = "kubernetes"
  builds_dir = "/builds"
  [runners.kubernetes]
    [[runners.kubernetes.volumes.empty_dir]]
      name = "repo"
      mount_path = "/builds"
      medium = "Memory"

Persistent per-concurrency build volumes

History
  • Support for variable injection to pvc.name introduced in GitLab 16.3.

The build directories in Kubernetes CI jobs are ephemeral by default. If you want to persist your Git clone across jobs (to make GIT_STRATEGY=fetch work), you must mount a persistent volume claim for your build folder. Because multiple jobs can run concurrently, you must either use a ReadWriteMany volume, or have one volume for each potential concurrent job on the same runner. The latter is likely to be more performant. Here is an example of such a configuration:

concurrent = 4

[[runners]]
  executor = "kubernetes"
  builds_dir = "/mnt/builds"
  [runners.kubernetes]
    [[runners.kubernetes.volumes.pvc]]
      # CI_CONCURRENT_ID identifies parallel jobs of the same runner.
      name = "build-pvc-$CI_CONCURRENT_ID"
      mount_path = "/mnt/builds"

In this example, create the persistent volume claims named build-pvc-0 to build-pvc-3 yourself. Create as many as the runner’s concurrent setting dictates.

Use a helper image

After you set the security policy, the helper image must conform to the policy. The image does not receive privileges from the root group, so you must ensure that the user ID is part of the root group.

note
If you only need the nonroot environment, you can use the GitLab Runner UBI and GitLab Runner Helper UBI OpenShift (OCP) images instead of a helper image.

The following example creates a user and group called nonroot and sets the helper image to run as that user.

ARG tag
FROM registry.gitlab.com/gitlab-org/ci-cd/gitlab-runner-ubi-images/gitlab-runner-helper-ocp:${tag}
USER root
RUN groupadd -g 59417 nonroot && \
    useradd -u 59417 nonroot -g nonroot
WORKDIR /home/nonroot
USER 59417:59417

Using Docker in builds

When you use Docker in your builds, there are several considerations you should be aware of.

Exposed /var/run/docker.sock

There are certain risks if you use the runners.kubernetes.volumes.host_path option to expose the /var/run/docker.sock of your host into your build container. The node’s containers are accessible from the build container, and depending on if you are running builds in the same cluster as your production containers, it might not be wise to do that.

Using docker:dind

If you run the docker:dind, also called the docker-in-docker image, containers must run in privileged mode. This may have potential risks and cause additional issues.

The Docker daemon runs as a separate container in the pod because it is started as a service, typically in the .gitlab-ci.yml. Containers in pods only share volumes assigned to them and an IP address, that they use to communicate with each other with localhost. The docker:dind container does not share /var/run/docker.sock and the docker binary tries to use it by default.

To configure the client use TCP to contact the Docker daemon, in the other container, include the environment variables of the build container:

  • DOCKER_HOST=tcp://<hostname>:2375 for no TLS connection.
  • DOCKER_HOST=tcp://<hostname>:2376 for TLS connection.

For hostname set the value to:

  • localhost for GitLab Runner 12.7 and earlier, and Kubernetes 1.6 and earlier.
  • docker for GitLab Runner 12.8 and later, and Kubernetes 1.7 and later.

In Docker 19.03 and later, TLS is enabled by default but you must map certificates to your client. You can enable non-TLS connection for DIND or mount certificates. For more information, see Use Docker In Docker Workflow with Docker executor.

Prevent host kernel exposure

If you use docker:dind or /var/run/docker.sock, the Docker daemon has access to the underlying kernel of the host machine. This means that any limits set in the pod do not work when Docker images are built. The Docker daemon reports the full capacity of the node, regardless of limits imposed on the Docker build containers spawned by Kubernetes.

If you run build containers in privileged mode, or if /var/run/docker.sock is exposed, the host kernel may become exposed to build containers. To minimize exposure, specify a label in the node_selector option. This ensures that the node matches the labels before any containers can be deployed to the node. For example, if you specify the label role=ci, the build containers only run on nodes labeled role=ci, and all other production services run on other nodes.

To further separate build containers, you can use node taints. Taints prevent other pods from scheduling on the same nodes as the build pods, without extra configuration for the other pods.

Use kaniko to build Docker images

You can use kaniko to build Docker images inside a Kubernetes cluster.

Kaniko works without the Docker daemon and builds images without privileged access.

For more information, see Building images with kaniko and GitLab CI/CD.

There is a known issue when using kaniko to build multi-stage Dockerfiles. If a pipeline job includes an after_script section, when the after_script section is executed it fails with the following error message. The job still completes successfully.

OCI runtime exec failed: exec failed: container_linux.go:380: starting container process caused: chdir to cwd
("/workspace") set in config.json failed: no such file or directory: unknown

The section fails because kaniko deletes its container’s WORKDIR when building multi-stage Dockerfiles. This prevents kubectl exec (and the analogous SDK API) from attaching to the container.

Two workarounds exists for this issue:

  • Add --ignore-path /workspace to the kaniko executor invocation.
  • Add mkdir -p /workspace to the job’s script after the kaniko executor invocation.

For more information, see issue 30769.

Restrict Docker images and services

History
  • Added for the Kubernetes executor in GitLab Runner 14.2.

You can restrict the Docker images that are used to run your jobs. To do this, you specify wildcard patterns. For example, to allow images from your private Docker registry only:

[[runners]]
  (...)
  executor = "kubernetes"
  [runners.kubernetes]
    (...)
    allowed_images = ["my.registry.tld:5000/*:*"]
    allowed_services = ["my.registry.tld:5000/*:*"]

Or, to restrict to a specific list of images from this registry:

[[runners]]
  (...)
  executor = "kubernetes"
  [runners.kubernetes]
    (...)
    allowed_images = ["my.registry.tld:5000/ruby:*", "my.registry.tld:5000/node:*"]
    allowed_services = ["postgres:9.4", "postgres:latest"]

Restrict Docker pull policies

History

In the .gitlab-ci.yml file, you can specify a pull policy. This policy determines how a CI/CD job should fetch images.

To restrict which pull policies can be used in the .gitlab-ci.yml file, you can use allowed_pull_policies.

For example, to allow only the always and if-not-present pull policies:

[[runners]]
  (...)
  executor = "kubernetes"
  [runners.kubernetes]
    (...)
    allowed_pull_policies = ["always", "if-not-present"]
  • If you don’t specify allowed_pull_policies, the default is the value in the pull_policy keyword.
  • If you don’t specify pull_policy, the cluster’s image default pull policy is used.
  • The existing pull_policy keyword must not include a pull policy that is not specified in allowed_pull_policies. If it does, the job returns an error.

Job execution

GitLab Runner uses kube attach instead of kube exec by default. This should avoid problems like when a job is marked successful midway in environments with an unstable network.

If you experience problems after updating to GitLab Runner 14.0, toggle the feature flag FF_USE_LEGACY_KUBERNETES_EXECUTION_STRATEGY to true and submit an issue.

Follow issue #27976 for progress on legacy execution strategy removal.

Configure the number of request attempts to the Kubernetes API

By default, the Kubernetes executor retries specific requests to the Kubernetes API after five failed attempts. The delay is controlled by a backoff algorithm with a 500 millisecond floor and a customizable ceiling with default value of two second. To configure the number of retries and backoff ceiling, use the retry_limit and retry_backoff_max options respectively in the config.toml file. The following failures are automatically retried:

To control the amount of retries for each error, use the retry_limits option. The rety_limits specifies the amount of retries for each error separately, and is a map of error messages to the amount of retries. The error message can be a substring of the error message returned by the Kubernetes API. The retry_limits option has precedence over the retry_limit option.

For example, if you need to control the number of TLS related errors in your environment, you can configure the retry_limits option to retry those errors 10 times instead of the default of five times:

[[runners]]
  name = "myRunner"
  url = "https://gitlab.example.com/"
  executor = "kubernetes"
  [runners.kubernetes]
    retry_limit = 5

    [runners.kubernetes.retry_limits]
        "TLS handshake timeout" = 10
        "tls: internal error" = 10

To retry an entirely different error, such as exceeded quota 20 times:

[[runners]]
  name = "myRunner"
  url = "https://gitlab.example.com/"
  executor = "kubernetes"
  [runners.kubernetes]
    retry_limit = 5

    [runners.kubernetes.retry_limits]
        "exceeded quota" = 20

Container entrypoint known issues

History
note
In 15.0, GitLab Runner uses the entrypoint defined in a Docker image when used with the Kubernetes executor with kube attach. In GitLab 15.1 and later, the entrypoint defined in a Docker image is used with the Kubernetes executor when FF_KUBERNETES_HONOR_ENTRYPOINT is set.

The container entry point has the following known issues:

Restrict access to job variables

When using Kubernetes executor, users with access to the Kubernetes cluster can read variables used in the job. By default, job variables are stored in:

  • Pod’s environment section

To restrict access to job variable data, you should use role-based access control (RBAC) so that only GitLab administrators have access to the namespace used by the GitLab Runner.

If you need other users to access the GitLab Runner namespace, set the following verbs to restrict the type of access users have in the GitLab Runner namespace:

  • For pods and configmaps:
    • get
    • watch
    • list
  • For pods/exec and pods/attach, use create.

Example RBAC definition for authorized users:

kind: Role
apiVersion: rbac.authorization.k8s.io/v1
metadata:
  name: gitlab-runner-authorized-users
rules:
- apiGroups: [""]
  resources: ["configmaps", "pods"]
  verbs: ["get", "watch", "list"]
- apiGroups: [""]
  resources: ["pods/exec", "pods/attach"]
  verbs: ["create"]

Resources check during prepare step

History

Prerequisites:

  • image_pull_secrets or service_account is set.
  • resource_availability_check_max_attempts is set to a number greater than zero.
  • Kubernetes serviceAccount used with the get and list permissions.

GitLab Runner checks if the new service accounts or secrets are available with a 5-second interval between each try.

  • In GitLab 15.0 and 15.1, you cannot disable this feature and it defaults to 5 when a negative value is set.
  • In GitLab 15.0.1, 15.1.1, 15.2 and later, this feature is disabled by default. To enable this feature, set resource_availability_check_max_attempts to any value other than 0. The value you set defines the amount of times the runner checks for service accounts or secrets.

Overwrite the Kubernetes namespace

Prerequisites:

  • In the values.yml file for GitLab Runner Helm charts, rbac.clusterWideAccess is set to true.
  • The runner has permissions configured in the core API group.

You can overwrite Kubernetes namespaces to designate a namespace for CI purposes, and deploy a custom set of pods to it. The pods spawned by the runner are in the overwritten namespace to enable access between containers during the CI stages.

To overwrite the Kubernetes namespace for each CI/CD job, set the KUBERNETES_NAMESPACE_OVERWRITE variable in the .gitlab-ci.yml file.

variables:
  KUBERNETES_NAMESPACE_OVERWRITE: ci-${CI_COMMIT_REF_SLUG}
note
This variable does not create a namespace on your cluster. Ensure that the namespace exists before you run the job.

To use only designated namespaces during CI runs, in the config.toml file, define a regular expression for namespace_overwrite_allowed:

[runners.kubernetes]
    ...
    namespace_overwrite_allowed = "ci-.*"