GitLab Runner Autoscaling

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You can use GitLab Runner autoscaling to automatically scale the runner on public cloud instances. When you configure a runner to use autoscaler, you can handle increased CI/CD job loads by running multiple jobs simultaneously on your cloud infrastructure.

In addition to the autoscaling options for public cloud instances, you can use the following container orchestration solutions for hosting and scaling a runner fleet.

  • Red Hat OpenShift Kubernetes clusters
  • Kubernetes clusters: AWS EKS, Azure, on-premise
  • Amazon Elastic Container Services clusters on AWS Fargate

Configure the runner manager

You must configure the runner manager to use GitLab Runner Autoscaling, both the Docker Machine Autoscaling solution and the GitLab Runner Autoscaler.

The runner manager is a type of runner that creates multiple runners for autoscaling. It continuously polls GitLab for jobs and interacts with the public cloud infrastructure to create a new instance to execute jobs. The runner manager must run on a host machine that has GitLab Runner installed. Choose a distribution that Docker and GitLab Runner supports, like Ubuntu, Debian, CentOS, or RHEL.

  1. Create an instance to host the runner manager. This must not be a spot instance (AWS), or spot virtual machine (GCP, Azure).
  2. Install GitLab Runner on the instance.
  3. Add the cloud provider credentials to the Runner Manager host machine.

You can host the runner manager in a container. For GitLab-hosted runners, the runner manager is hosted on a virtual machine instance.

Example credentials configuration for GitLab Runner Docker Machine Autoscaling

This snippet is in the runners.machine section of the config.toml file.

TOML Copy to clipboard 
  [runners.machine]
    IdleCount = 1
    IdleTime = 1800
    MaxBuilds = 10
    MachineDriver = "amazonec2"
    MachineName = "gitlab-docker-machine-%s"
    MachineOptions = [
      "amazonec2-access-key=XXXX",
      "amazonec2-secret-key=XXXX",
      "amazonec2-region=us-central-1",
      "amazonec2-vpc-id=vpc-xxxxx",
      "amazonec2-subnet-id=subnet-xxxxx",
      "amazonec2-zone=x",
      "amazonec2-use-private-address=true",
      "amazonec2-security-group=xxxxx",
    ]

The credentials file is optional. You can use an AWS Identity and Access Management (IAM) instance profile for the runner manager in the AWS environment. If you do not want to host the runner manager in AWS, you can use the credentials file.

Implement a fault-tolerant design

Start with at least two runner managers that use the same runner tags to create a fault-tolerant design and prevent runner manager host failures.

For example, on GitLab.com, multiple runner managers are configured for hosted runners on Linux. Each runner manager has the tag saas-linux-small-amd64.

Use observability and runner fleet metrics when you adjust autoscaling parameters to balance efficiency and performance for your organization’s CI/CD workloads.

Configure runner autoscaling executors

After you configure the runner manager, configure the executors specific to autoscaling:

You should use the Instance and Docker Autoscaling executors, as these comprise the technology that replaces the Docker Machine autoscaler.