• The global section
  • log_format examples (truncated)
    • runner
    • text
    • json
  • How check_interval works
• The [session_server] section
• The [[runners]] section
  • How clone_url works
• The executors
• The shells
  • Use a POSIX-compliant shell
• The [runners.docker] section
  • The [[runners.docker.services]] section
  • Volumes in the [runners.docker] section
    • Example 1: Add a data volume
    • Example 2: Mount a host directory as a data volume
  • Use a private container registry
    • Support for GitLab integrated registry
    • Precedence of Docker authorization resolving
• The [runners.parallels] section
• The [runners.virtualbox] section
• Overriding the base VM image
• The [runners.ssh] section
• The [runners.machine] section
  • The [[runners.machine.autoscaling]] sections
  • Periods syntax
• The [runners.custom] section
• The [runners.cache] section
  • The [runners.cache.s3] section
    • Use KMS key encryption in S3 bucket for runner cache
    • Enable IAM roles for Kubernetes ServiceAccount resources
  • The [runners.cache.gcs] section
  • The [runners.cache.azure] section
• The [runners.kubernetes] section
• Helper image
  • Runner images that use an old version of Alpine Linux
  • Alpine 3.14 and 3.15 pwsh images
  • Helper image registry
  • Override the helper image
    • When using PowerShell Core
• The [runners.custom_build_dir] section
• The [runners.referees] section
  • Use the Metrics Runner referee
  • Configure the Metrics Runner Referee for GitLab Runner
• Deploy to multiple servers using GitLab CI/CD

Advanced configuration

You can change the behavior of GitLab Runner and of individual registered runners.

To do this, you modify a file called config.toml, which uses the TOML format.

GitLab Runner does not require a restart when you change most options. This includes parameters in the [[runners]] section and most parameters in the global section, except for listen_address. If a runner was already registered, you don’t need to register it again.

GitLab Runner checks for configuration modifications every 3 seconds and reloads if necessary. GitLab Runner also reloads the configuration in response to the SIGHUP signal.

You can find the config.toml file in:

• /etc/gitlab-runner/ on *nix systems when GitLab Runner is executed as root (this is also the path for service configuration)
• ~/.gitlab-runner/ on *nix systems when GitLab Runner is executed as non-root
• ./ on other systems

The global section

These settings are global. They apply to all runners.

Configuration example:

concurrent = 4
log_level = "warning"

log_format examples (truncated)

runner

Runtime platform                                    arch=amd64 os=darwin pid=37300 revision=HEAD version=development version
Starting multi-runner from /etc/gitlab-runner/config.toml...  builds=0
WARNING: Running in user-mode.
WARNING: Use sudo for system-mode:
WARNING: $ sudo gitlab-runner...

Configuration loaded                                builds=0
listen_address not defined, metrics & debug endpoints disabled  builds=0
[session_server].listen_address not defined, session endpoints disabled  builds=0

text

INFO[0000] Runtime platform                              arch=amd64 os=darwin pid=37773 revision=HEAD version="development version"
INFO[0000] Starting multi-runner from /etc/gitlab-runner/config.toml...  builds=0
WARN[0000] Running in user-mode.
WARN[0000] Use sudo for system-mode:
WARN[0000] $ sudo gitlab-runner...
INFO[0000]
INFO[0000] Configuration loaded                          builds=0
INFO[0000] listen_address not defined, metrics & debug endpoints disabled  builds=0
INFO[0000] [session_server].listen_address not defined, session endpoints disabled  builds=0

json

{"arch":"amd64","level":"info","msg":"Runtime platform","os":"darwin","pid":38229,"revision":"HEAD","time":"2020-06-05T15:57:35+02:00","version":"development version"}
{"builds":0,"level":"info","msg":"Starting multi-runner from /etc/gitlab-runner/config.toml...","time":"2020-06-05T15:57:35+02:00"}
{"level":"warning","msg":"Running in user-mode.","time":"2020-06-05T15:57:35+02:00"}
{"level":"warning","msg":"Use sudo for system-mode:","time":"2020-06-05T15:57:35+02:00"}
{"level":"warning","msg":"$ sudo gitlab-runner...","time":"2020-06-05T15:57:35+02:00"}
{"level":"info","msg":"","time":"2020-06-05T15:57:35+02:00"}
{"builds":0,"level":"info","msg":"Configuration loaded","time":"2020-06-05T15:57:35+02:00"}
{"builds":0,"level":"info","msg":"listen_address not defined, metrics \u0026 debug endpoints disabled","time":"2020-06-05T15:57:35+02:00"}
{"builds":0,"level":"info","msg":"[session_server].listen_address not defined, session endpoints disabled","time":"2020-06-05T15:57:35+02:00"}

How check_interval works

If more than one [[runners]] section exists in config.toml, the interval between requests to GitLab are more frequent than you might expect. GitLab Runner contains a loop that constantly schedules a request to the GitLab instance it’s configured for.

GitLab Runner tries to ensure that subsequent requests for each runner are done in the specified interval. To do this, it divides the value of check_interval by the number of [[runners]] sections. The loop iterates over all sections, schedules a request for each, and sleeps for the calculated amount of time. Things get interesting when the runners are tied to a different GitLab instance. Consider the following example.

If you set check_interval = 10, and there are two runners (runner-1 and runner-2), a request is made each 10 seconds. Here is an example of the loop in this case:

1. Get check_interval value (10s).
2. Get list of runners (runner-1, runner-2).
3. Calculate the sleep interval (10s / 2 = 5s).
4. Start an infinite loop:
   1. Request a job for runner-1.
   2. Sleep for 5s.
   3. Request a job for runner-2.
   4. Sleep for 5s.
   5. Repeat.

In this example, a request from the runner’s process is made every 5 seconds. If runner-1 and runner-2 are connected to the same GitLab instance, this GitLab instance also receives a new request from this runner every 5 seconds.

Between the first request for runner-1 and second request for runner-1 there are two sleep periods. Each one takes 5 seconds, so it’s approximately 10 seconds between subsequent requests for runner-1. The same applies for runner-2.

If you define more runners, the sleep interval is smaller. However, a request for a runner is repeated after all requests for the other runners and their sleep periods are called.

The [session_server] section

The [session_server] section lets users interact with jobs, for example, in the interactive web terminal.

The [session_server] section should be specified at the root level, not per runner. It should be defined outside the [[runners]] section.

[session_server]
  listen_address = "[::]:8093" #  listen on all available interfaces on port 8093
  advertise_address = "runner-host-name.tld:8093"
  session_timeout = 1800

Both listen_address and advertise_address should be in the form of host:port, where host may be an IP address (127.0.0.1:8093) or a domain (my-runner.example.com:8093). The runner uses this information to create a TLS certificate, for a secure connection.

To disable the session server and terminal support, delete the [session_server] section.

If you are using the GitLab Runner Docker image, you must expose port 8093 by adding -p 8093:8093 to your docker run command.

The [[runners]] section

Each [[runners]] section defines one runner.

Example:

[[runners]]
  name = "ruby-2.7-docker"
  url = "https://CI/"
  token = "TOKEN"
  limit = 0
  executor = "docker"
  builds_dir = ""
  shell = ""
  environment = ["ENV=value", "LC_ALL=en_US.UTF-8"]
  clone_url = "http://gitlab.example.local"

How clone_url works

When the GitLab instance is available at a URL that the runner can’t use, you can configure a clone_url.

For example, a firewall might prevent the runner from reaching the URL. If the runner can reach the node on 192.168.1.23, set the clone_url to http://192.168.1.23.

If the clone_url is set, the runner constructs a clone URL in the form of http://gitlab-ci-token:s3cr3tt0k3n@192.168.1.23/namespace/project.git.

The executors

The following executors are available.

The shells

The available shells can run on different platforms.

When the shell option is set to bash or sh, Bash’s ANSI-C quoting is used to shell escape job scripts.

Use a POSIX-compliant shell

In GitLab Runner 14.9 and later, enable the feature flag named FF_POSIXLY_CORRECT_ESCAPES to use a POSIX-compliant shell (like dash). When enabled, “Double Quotes”, which is POSIX-compliant shell escaping mechanism, is used.

The [runners.docker] section

This defines the Docker Container parameters.

The [[runners.docker.services]] section

Specify additional services that should be run with the job. Visit the Docker Registry for the list of available images. Each service runs in a separate container and is linked to the job.

Example:

[runners.docker]
  host = ""
  hostname = ""
  tls_cert_path = "/Users/ayufan/.boot2docker/certs"
  image = "ruby:2.7"
  memory = "128m"
  memory_swap = "256m"
  memory_reservation = "64m"
  oom_kill_disable = false
  cpuset_cpus = "0,1"
  cpus = "2"
  dns = ["8.8.8.8"]
  dns_search = [""]
  privileged = false
  userns_mode = "host"
  cap_add = ["NET_ADMIN"]
  cap_drop = ["DAC_OVERRIDE"]
  devices = ["/dev/net/tun"]
  disable_cache = false
  wait_for_services_timeout = 30
  cache_dir = ""
  volumes = ["/data", "/home/project/cache"]
  extra_hosts = ["other-host:127.0.0.1"]
  shm_size = 300000
  volumes_from = ["storage_container:ro"]
  links = ["mysql_container:mysql"]
  allowed_images = ["ruby:*", "python:*", "php:*"]
  allowed_services = ["postgres:9", "redis:*", "mysql:*"]
  [[runners.docker.services]]
    name = "registry.example.com/svc1"
    alias = "svc1"
    entrypoint = ["entrypoint.sh"]
    command = ["executable","param1","param2"]
  [[runners.docker.services]]
    name = "redis:2.8"
    alias = "cache"
  [[runners.docker.services]]
    name = "postgres:9"
    alias = "postgres-db"
  [runners.docker.sysctls]
    "net.ipv4.ip_forward" = "1"

Volumes in the [runners.docker] section

View the complete guide of Docker volume usage.

The following examples show how to specify volumes in the [runners.docker] section.

Example 1: Add a data volume

A data volume is a specially-designated directory in one or more containers that bypasses the Union File System. Data volumes are designed to persist data, independent of the container’s life cycle.

[runners.docker]
  host = ""
  hostname = ""
  tls_cert_path = "/Users/ayufan/.boot2docker/certs"
  image = "ruby:2.7"
  privileged = false
  disable_cache = true
  volumes = ["/path/to/volume/in/container"]

This example creates a new volume in the container at /path/to/volume/in/container.

Example 2: Mount a host directory as a data volume

When you want to store directories outside the container, you can mount a directory from your Docker daemon’s host into a container:

[runners.docker]
  host = ""
  hostname = ""
  tls_cert_path = "/Users/ayufan/.boot2docker/certs"
  image = "ruby:2.7"
  privileged = false
  disable_cache = true
  volumes = ["/path/to/bind/from/host:/path/to/bind/in/container:rw"]

This example uses /path/to/bind/from/host of the CI/CD host in the container at /path/to/bind/in/container.

GitLab Runner 11.11 and later mount the host directory for the defined services as well.

Use a private container registry

To use private registries as a source of images for your jobs, you can set the authorization configuration in a CI/CD variable named DOCKER_AUTH_CONFIG. You can set the variable in the project’s CI/CD settings or in the config.toml file.

Using private registries with the if-not-present pull policy may introduce security implications. To fully understand how pull policies work, read the pull policies documentation.

For a detailed example, visit the Using Docker images documentation.

The steps performed by the runner can be summed up as:

1. The registry name is found from the image name.
2. If the value is not empty, the executor searches for the authentication configuration for this registry.
3. Finally, if an authentication corresponding to the specified registry is found, subsequent pulls makes use of it.

Now that the runner is set up to authenticate against your private registry, learn how to configure the .gitlab-ci.yml file to use that registry.

Support for GitLab integrated registry

GitLab sends credentials for its integrated registry along with the job’s data. These credentials are automatically added to the registry’s authorization parameters list.

After this step, authorization against the registry proceeds similarly to configuration added with the DOCKER_AUTH_CONFIG variable.

In your jobs, you can use any image from your GitLab integrated registry, even if the image is private or protected. For information on the images jobs have access to, read the CI/CD job token documentation documentation.

Precedence of Docker authorization resolving

As described earlier, GitLab Runner can authorize Docker against a registry by using credentials sent in different way. To find a proper registry, the following precedence is taken into account:

1. Credentials configured with DOCKER_AUTH_CONFIG.
2. Credentials configured locally on the GitLab Runner host with ~/.docker/config.json or ~/.dockercfg files (for example, by running docker login on the host).
3. Credentials sent by default with a job’s payload (for example, credentials for the integrated registry described earlier).

The first credentials found for the registry are used. So for example, if you add credentials for the integrated registry with the DOCKER_AUTH_CONFIG variable, then the default credentials are overridden.

The [runners.parallels] section

The following parameters are for Parallels.

Example:

[runners.parallels]
  base_name = "my-parallels-image"
  template_name = ""
  disable_snapshots = false

The [runners.virtualbox] section

The following parameters are for VirtualBox. This executor relies on the vboxmanage executable to control VirtualBox machines, so you have to adjust your PATH environment variable on Windows hosts: PATH=%PATH%;C:\Program Files\Oracle\VirtualBox.

Example:

[runners.virtualbox]
  base_name = "my-virtualbox-image"
  base_snapshot = "my-image-snapshot"
  disable_snapshots = false

Overriding the base VM image

For both the Parallels and VirtualBox executors, you can override the base VM name specified by base_name. To do this, use the image parameter in the .gitlab-ci.yml file.

For backward compatibility, you cannot override this value by default. Only the image specified by base_name is allowed.

To allow users to select a VM image by using the .gitlab-ci.yml image parameter:

[runners.virtualbox]
  ...
  allowed_images = [".*"]

In the example, any existing VM image can be used.

The allowed_images parameter is a list of regular expressions. Configuration can be as precise as required. For instance, if you want to allow only certain VM images, you can use regex like:

[runners.virtualbox]
  ...
  allowed_images = ["^allowed_vm[1-2]$"]

In this example, only allowed_vm1 and allowed_vm2 are allowed. Any other attempts will result in an error.

The [runners.ssh] section

The following parameters define the SSH connection.

Example:

[runners.ssh]
  host = "my-production-server"
  port = "22"
  user = "root"
  password = "production-server-password"
  identity_file = ""

The [runners.machine] section

Added in GitLab Runner v1.1.0.

The following parameters define the Docker Machine-based autoscaling feature. More details can be found in the separate runner autoscale documentation.

The [[runners.machine.autoscaling]] sections

Example:

[runners.machine]
  IdleCount = 5
  IdleTime = 600
  MaxBuilds = 100
  MachineName = "auto-scale-%s"
  MachineDriver = "google" # Refer to Docker Machine docs on how to authenticate: https://docs.docker.com/machine/drivers/gce/#credentials
  MachineOptions = [
      # Additional machine options can be added using the Google Compute Engine driver.
      # If you experience problems with an unreachable host (ex. "Waiting for SSH"),
      # you should remove optional parameters to help with debugging.
      # https://docs.docker.com/machine/drivers/gce/
      "google-project=GOOGLE-PROJECT-ID",
      "google-zone=GOOGLE-ZONE", # e.g. 'us-central1-a', full list in https://cloud.google.com/compute/docs/regions-zones/
  ]
  [[runners.machine.autoscaling]]
    Periods = ["* * 9-17 * * mon-fri *"]
    IdleCount = 50
    IdleCountMin = 5
    IdleScaleFactor = 1.5 # Means that current number of Idle machines will be 1.5*in-use machines,
                          # no more than 50 (the value of IdleCount) and no less than 5 (the value of IdleCountMin)
    IdleTime = 3600
    Timezone = "UTC"
  [[runners.machine.autoscaling]]
    Periods = ["* * * * * sat,sun *"]
    IdleCount = 5
    IdleTime = 60
    Timezone = "UTC"

Periods syntax

The Periods setting contains an array of string patterns of time periods represented in a cron-style format. The line contains following fields:

[second] [minute] [hour] [day of month] [month] [day of week] [year]

Like in the standard cron configuration file, the fields can contain single values, ranges, lists, and asterisks. View a detailed description of the syntax.

The [runners.custom] section

The following parameters define configuration for the custom executor.

The [runners.cache] section

The following parameters define the distributed cache feature. View details in the runner autoscale documentation.

The cache mechanism uses pre-signed URLs to upload and download cache. URLs are signed by GitLab Runner on its own instance. It does not matter if the job’s script (including the cache upload/download script) are executed on local or external machines. For example, shell or docker executors run their scripts on the same machine where the GitLab Runner process is running. At the same time, virtualbox or docker+machine connects to a separate VM to execute the script. This process is for security reasons: minimizing the possibility of leaking the cache adapter’s credentials.

If the S3 cache adapter is configured to use an IAM instance profile, the adapter uses the profile attached to the GitLab Runner machine. Similarly for GCS cache adapter, if configured to use the CredentialsFile. The file needs to be present on the GitLab Runner machine.

This table lists config.toml, CLI options, and ENV variables for register.

The [runners.cache.s3] section

The following parameters define S3 storage for cache.

In GitLab Runner 11.2 and earlier, these settings were in the global [runners.cache] section.

Example:

[runners.cache]
  Type = "s3"
  Path = "path/to/prefix"
  Shared = false
  [runners.cache.s3]
    ServerAddress = "s3.amazonaws.com"
    AccessKey = "AWS_S3_ACCESS_KEY"
    SecretKey = "AWS_S3_SECRET_KEY"
    BucketName = "runners-cache"
    BucketLocation = "eu-west-1"
    Insecure = false
    ServerSideEncryption = "KMS"
    ServerSideEncryptionKeyID = "alias/my-key"

If any of ServerAddress, AccessKey or SecretKey aren’t specified and AuthenticationType is not provided, the S3 client uses the IAM instance profile available to the gitlab-runner instance. In an autoscale configuration, this is not the on-demand machine that jobs are executed on. If ServerAddress, AccessKey and SecretKey are all specified but AuthenticationType is not provided, access-key will be used as the authentication type.

When you use Helm charts to install GitLab Runner, and rbac.create is set to true in the values.yaml file, a ServiceAccount is created. This ServiceAccount’s annotations are retrieved from the rbac.serviceAccountAnnotations section.

For runners on Amazon EKS, you can specify an IAM role to assign to the service account. The specific annotation needed is: eks.amazonaws.com/role-arn: arn:aws:iam::<ACCOUNT_ID>:role/<IAM_ROLE_NAME>.

The IAM policy for this role must have permissions to do the following actions for the specified bucket:

• “s3:PutObject”
• “s3:GetObjectVersion”
• “s3:GetObject”
• “s3:DeleteObject”

If you use ServerSideEncryption of type KMS, this role must also have permission to do the following actions for the specified AWS KMS Key:

• “kms:Encrypt”
• “kms:Decrypt”
• “kms:ReEncrypt*”
• “kms:GenerateDataKey*”
• “kms:DescribeKey”

ServerSideEncryption of type SSE-C is currently not supported. SSE-C requires that the headers, which contain the user-supplied key, are provided for the download request, in addition to the presigned URL. This would mean passing the key material to the job, where the key can’t be kept safe. This does have the potential to leak the decryption key. A discussion about this issue is in this merge request.

Use KMS key encryption in S3 bucket for runner cache

The GenerateDataKey API uses the KMS symmetric key to create a data key for client-side encryption (https://docs.aws.amazon.com/kms/latest/APIReference/API_GenerateDataKey.html). KMS key configuration must be as follows:

The IAM policy for the role assigned to the ServiceAccount defined in rbac.serviceAccountName must have permissions to do the following actions for the KMS Key:

• kms:GetPublicKey
• kms:Decrypt
• kms:Encrypt
• kms:DescribeKey
• kms:GenerateDataKey

Enable IAM roles for Kubernetes ServiceAccount resources

To use IAM roles for service accounts, an IAM OIDC provider must exist for your cluster. After an IAM OIDC provider is associated with your cluster, you can create an IAM role to associate to the service account of the runner.

1. On the Create Role window, under Select type of trusted entity, select Web Identity.

2. On the Trusted Relationships tab of the role:

   • The Trusted entities section must have the format: arn:aws:iam::<ACCOUNT_ID>:oidc-provider/oidc.eks.<AWS_REGION>.amazonaws.com/id/<OIDC_ID>. The OIDC ID can be found on EKS cluster’s Configuration tab.

   • The Condition section must have the GitLab Runner service account defined in rbac.serviceAccountName or the default service account created if rbac.create is set to true:

     Condition	Key	Value
     StringEquals	oidc.eks.<AWS_REGION>.amazonaws.com/id/<OIDC_ID>:sub	system:serviceaccount:<GITLAB_RUNNER_NAMESPACE>:<GITLAB_RUNNER_SERVICE_ACCOUNT>

The [runners.cache.gcs] section

The following parameters define native support for Google Cloud Storage. To view where these values come from, view the Google Cloud Storage (GCS) Authentication documentation.

Examples:

Credentials configured directly in config.toml file:

[runners.cache]
  Type = "gcs"
  Path = "path/to/prefix"
  Shared = false
  [runners.cache.gcs]
    AccessID = "cache-access-account@test-project-123456.iam.gserviceaccount.com"
    PrivateKey = "-----BEGIN PRIVATE KEY-----\nXXXXXX\n-----END PRIVATE KEY-----\n"
    BucketName = "runners-cache"

Credentials in JSON file downloaded from GCP:

[runners.cache]
  Type = "gcs"
  Path = "path/to/prefix"
  Shared = false
  [runners.cache.gcs]
    CredentialsFile = "/etc/gitlab-runner/service-account.json"
    BucketName = "runners-cache"

Application Default Credentials (ADC) from the metadata server in GCP:

When you use GitLab Runner with Google Cloud ADC, you typically use the default service account. Then you don’t need to supply credentials for the instance:

[runners.cache]
  Type = "gcs"
  Path = "path/to/prefix"
  Shared = false
  [runners.cache.gcs]
    BucketName = "runners-cache"

If you use ADC, be sure that the service account that you use has the iam.serviceAccounts.signBlob permission. Typically this is done by granting the Service Account Token Creator role to the service account.

The [runners.cache.azure] section

The following parameters define native support for Azure Blob Storage. To learn more, view the Azure Blob Storage documentation. While S3 and GCS use the word bucket for a collection of objects, Azure uses the word container to denote a collection of blobs.

Example:

[runners.cache]
  Type = "azure"
  Path = "path/to/prefix"
  Shared = false
  [runners.cache.azure]
    AccountName = "<AZURE STORAGE ACCOUNT NAME>"
    AccountKey = "<AZURE STORAGE ACCOUNT KEY>"
    ContainerName = "runners-cache"
    StorageDomain = "blob.core.windows.net"

The [runners.kubernetes] section

The following parameters define Kubernetes behavior. For more parameters, see the documentation for the Kubernetes executor.

Example:

[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"
  image = "golang:1.8"
  privileged = true
  allow_privilege_escalation = true
  image_pull_secrets = ["docker-registry-credentials", "optional-additional-credentials"]
  allowed_images = ["ruby:*", "python:*", "php:*"]
  allowed_services = ["postgres:9.4", "postgres:latest"]
  [runners.kubernetes.node_selector]
    gitlab = "true"

Helper image

When you use docker, docker+machine, or kubernetes executors, GitLab Runner uses a specific container to handle Git, artifacts, and cache operations. This container is created from an image named helper image.

The helper image is available for amd64, arm, arm64, s390x, and ppc64le architectures. It contains a gitlab-runner-helper binary, which is a special compilation of GitLab Runner binary. It contains only a subset of available commands, as well as Git, Git LFS and SSL certificates store.

The helper image has a few flavors: alpine, alpine3.12, alpine3.13, alpine3.14, alpine3.15, alpine-latest, ubi-fips and ubuntu. The alpine image is currently the default due to its small footprint but can have DNS issues in some environments. Using helper_image_flavor = "ubuntu" will select the ubuntu flavor of the helper image.

In GitLab Runner 15.0 and later the alpine flavor is an alias for alpine3.15.

The alpine-latest flavor uses alpine:latest as its base image, which could potentially mean it will be more unstable.

When GitLab Runner is installed from the DEB/RPM packages, images for the supported architectures are installed on the host. When the runner prepares to execute the job, if the image in the specified version (based on the runner’s Git revision) is not found on Docker Engine, it is automatically loaded. Both the docker and docker+machine executors work this way.

For the alpine flavors, only the default alpine flavor image is included in the package. All other flavors will be downloaded from the registry.

The kubernetes executor and manual installations of GitLab Runner work differently.

• For manual installations, the gitlab-runner-helper binary is not included.
• For the kubernetes executor, the Kubernetes API doesn’t allow the gitlab-runner-helper image to be loaded from a local archive.

In both cases, GitLab Runner downloads the helper image. The GitLab Runner revision and architecture define which tag to download.

Runner images that use an old version of Alpine Linux

Images are built with multiple versions of Alpine Linux, so you can use a newer version of Alpine, but at the same time use older versions as well.

For the helper image, change the helper_image_flavor or read the Helper image section.

For the GitLab Runner image, follow the same logic, where alpine, alpine3.12, alpine3.13, alpine3.14, alpine3.15 or alpine-latest is used as a prefix in the image, before the version:

docker pull gitlab/gitlab-runner:alpine3.14-v14.4.0

Alpine 3.14 and 3.15 pwsh images

The pwsh Docker images do not yet include Alpine 3.14 and 3.15. Currently, alpine3.13 is the latest supported pwsh image.

Helper image registry

In GitLab 15.0 and later, the helper image is pulled from the GitLab Container Registry. In addition, helper images are only published in the GitLab Container Registry.

Before 15.0, you could configure this behavior to use images from Docker Hub.

Override the helper image

In some cases, you may need to override the helper image. There are many reasons for doing this:

1. To speed up jobs execution: In environments with slower internet connection, downloading the same image multiple times can increase the time it takes to execute a job. Downloading the helper image from a local registry, where the exact copy of gitlab/gitlab-runner-helper:XYZ is stored, can speed things up.

2. Security concerns: You may not want to download external dependencies that were not checked before. There might be a business rule to use only dependencies that were reviewed and stored in local repositories.

3. Build environments without internet access: In some cases, jobs are executed in an environment that has a dedicated, closed network. This doesn’t apply to the kubernetes executor, where the image still needs to be downloaded from an external registry that is available to the Kubernetes cluster.

4. Additional software: You may want to install some additional software to the helper image, like openssh to support submodules accessible with git+ssh instead of git+http.

In these cases, you can configure a custom image by using the helper_image configuration field, which is available for the docker, docker+machine, and kubernetes executors:

[[runners]]
  (...)
  executor = "docker"
  [runners.docker]
    (...)
    helper_image = "my.registry.local/gitlab/gitlab-runner-helper:tag"

The version of the helper image should be considered to be strictly coupled with the version of GitLab Runner. One of the main reasons for providing these images is that GitLab Runner is using the gitlab-runner-helper binary. This binary is compiled from part of the GitLab Runner source. This binary uses an internal API that is expected to be the same in both binaries.

By default, GitLab Runner references a gitlab/gitlab-runner-helper:XYZ image, where XYZ is based on the GitLab Runner architecture and Git revision. In GitLab Runner 11.3 and later, you can define the image version by using one of the version variables:

[[runners]]
  (...)
  executor = "docker"
  [runners.docker]
    (...)
    helper_image = "my.registry.local/gitlab/gitlab-runner-helper:x86_64-${CI_RUNNER_REVISION}"

With this configuration, GitLab Runner instructs the executor to use the image in version x86_64-${CI_RUNNER_REVISION}, which is based on its compilation data. After updating GitLab Runner to a new version, GitLab Runner tries to download the proper image. The image should be uploaded to the registry before upgrading GitLab Runner, otherwise the jobs start failing with a “No such image” error.

In GitLab Runner 13.2 and later, the helper image is tagged by $CI_RUNNER_VERSION in addition to $CI_RUNNER_REVISION. Both tags are valid and point to the same image.

[[runners]]
  (...)
  executor = "docker"
  [runners.docker]
    (...)
    helper_image = "my.registry.local/gitlab/gitlab-runner-helper:x86_64-v${CI_RUNNER_VERSION}"

When using PowerShell Core

An additional version of the helper image for Linux, which contains PowerShell Core, is published with the gitlab/gitlab-runner-helper:XYZ-pwsh tag.

The [runners.custom_build_dir] section

This section defines custom build directories parameters.

This feature, if not configured explicitly, is enabled by default for kubernetes, docker, docker-ssh, docker+machine, and docker-ssh+machine executors. For all other executors, it is disabled by default.

This feature requires that GIT_CLONE_PATH is in a path defined in runners.builds_dir. To use the builds_dir, use the $CI_BUILDS_DIR variable.

By default, this feature is enabled only for docker and kubernetes executors, because they provide a good way to separate resources. This feature can be explicitly enabled for any executor, but use caution when you use it with executors that share builds_dir and have concurrent > 1.

Example:

[runners.custom_build_dir]
  enabled = true

The [runners.referees] section

Use GitLab Runner referees to pass extra job monitoring data to GitLab. Referees are workers in the Runner Manager that query and collect additional data related to a job. The results are uploaded to GitLab as job artifacts.

Use the Metrics Runner referee

If the machine or container running the job exposes Prometheus metrics, GitLab Runner can query the Prometheus server for the entirety of the job duration. After the metrics are received, they are uploaded as a job artifact that can be used for analysis later.

Only the docker-machine executor supports the referee.

Configure the Metrics Runner Referee for GitLab Runner

Define [runner.referees] and [runner.referees.metrics] in your config.toml file within a [[runner]] section and add the following fields:

Here is a complete configuration example for node_exporter metrics:

[[runners]]
  [runners.referees]
    [runners.referees.metrics]
      prometheus_address = "http://localhost:9090"
      query_interval = 10
      metric_queries = [
        "arp_entries:rate(node_arp_entries{{selector}}[{interval}])",
        "context_switches:rate(node_context_switches_total{{selector}}[{interval}])",
        "cpu_seconds:rate(node_cpu_seconds_total{{selector}}[{interval}])",
        "disk_read_bytes:rate(node_disk_read_bytes_total{{selector}}[{interval}])",
        "disk_written_bytes:rate(node_disk_written_bytes_total{{selector}}[{interval}])",
        "memory_bytes:rate(node_memory_MemTotal_bytes{{selector}}[{interval}])",
        "memory_swap_bytes:rate(node_memory_SwapTotal_bytes{{selector}}[{interval}])",
        "network_tcp_active_opens:rate(node_netstat_Tcp_ActiveOpens{{selector}}[{interval}])",
        "network_tcp_passive_opens:rate(node_netstat_Tcp_PassiveOpens{{selector}}[{interval}])",
        "network_receive_bytes:rate(node_network_receive_bytes_total{{selector}}[{interval}])",
        "network_receive_drops:rate(node_network_receive_drop_total{{selector}}[{interval}])",
        "network_receive_errors:rate(node_network_receive_errs_total{{selector}}[{interval}])",
        "network_receive_packets:rate(node_network_receive_packets_total{{selector}}[{interval}])",
        "network_transmit_bytes:rate(node_network_transmit_bytes_total{{selector}}[{interval}])",
        "network_transmit_drops:rate(node_network_transmit_drop_total{{selector}}[{interval}])",
        "network_transmit_errors:rate(node_network_transmit_errs_total{{selector}}[{interval}])",
        "network_transmit_packets:rate(node_network_transmit_packets_total{{selector}}[{interval}])"
      ]

Metrics queries are in canonical_name:query_string format. The query string supports two variables that are replaced during execution:

For example, a shared GitLab Runner environment that uses the docker-machine executor would have a {selector} similar to node=shared-runner-123.

Deploy to multiple servers using GitLab CI/CD

To deploy to multiple servers by using GitLab CI/CD, create a single script that deploys to multiple servers, or create many scripts. It depends on what you’d like to do.