• Workflow
  • How the runner creates Kubernetes pods
• Connect to the Kubernetes API
• Configuration settings
  • CPU requests and limits
  • Memory requests and limits
  • Storage requests and limits
  • Other config.toml settings
  • Overwrite generated pod specifications (Alpha)
    • Merge patch strategy
    • JSON patch strategy
    • Strategic patch strategy
    • Best practices
  • Pod lifecycle
  • Default Annotations for job Pods
  • Configure the executor service account
  • Overwrite the Kubernetes namespace
  • Configure runner API permissions
  • Overwrite the Kubernetes default service account
  • Set the bearer token for Kubernetes API calls
  • Overwrite pod labels
  • Overwrite pod annotations
  • Overwrite container resources
  • Configuration example
• Resources check during prepare step
• Using the cache with the Kubernetes executor
• Configure volume types
  • hostPath volume
  • persistentVolumeClaim volume
  • configMap volume
  • secret volume
  • emptyDir volume
  • csi volume
  • Mount volumes on service containers
  • Custom volume mount
• Set a security policy for the pod
  • Use a helper image
• Set a security policy for the container
• Define a list of services
• Set a pull policy
• Specify the node to execute builds
  • Example for linux/arm64
  • Example for windows/amd64
• Define a list of node affinities
• Define nodes where pods are scheduled
• Add extra host aliases
• Configure a container lifecycle hook
  • KubernetesLifecycleExecAction
  • KubernetesLifecycleHTTPGet
  • KubernetesLifecycleHTTPGetHeader
  • KubernetesLifecycleTcpSocket
• Configure pod DNS settings
  • KubernetesDNSConfigOption
• Specify container capabilities
  • Default list of dropped capabilities
• Set the RuntimeClass
• Using Docker in builds
  • Exposed /var/run/docker.sock
  • Using docker:dind
  • Prevent host kernel exposure
  • Use kaniko to build Docker images
  • Restrict Docker images and services
  • Restrict Docker pull policies
• Job execution
  • Container entrypoint known issues
• Remove old runner pods
• Troubleshooting
  • Job failed (system failure): timed out waiting for pod to start
  • context deadline exceeded
  • Connection refused when attempting to communicate with the Kubernetes API
  • Error cleaning up pod and Job failed (system failure): prepare environment: waiting for pod running
  • request did not complete within requested timeout
  • fatal: unable to access 'https://gitlab-ci-token:token@example.com/repo/proj.git/': Could not resolve host: example.com
  • docker: Cannot connect to the Docker daemon at tcp://docker:2375. Is the docker daemon running?
  • curl: (35) OpenSSL SSL_connect: SSL_ERROR_SYSCALL in connection to github.com:443
  • MountVolume.SetUp failed for volume "kube-api-access-xxxxx" : chown is not supported by windows
  • Build pods are assigned the worker node’s IAM role instead of Runner IAM role
  • Preparation failed: failed to pull image 'image-name:latest': pull_policy ([Always]) defined in GitLab pipeline config is not one of the allowed_pull_policies ([])
  • Background processes cause jobs to hang and timeout
• Restrict access to job variables

Kubernetes executor

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.

Workflow

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.

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.

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.

Configuration settings

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

CPU requests and limits

Memory requests and limits

Storage requests and limits

Other config.toml settings

Overwrite generated pod specifications (Alpha)

This feature is in Alpha. 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 to the generated pod specification. You can configure multiple pod_spec settings.

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 json 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"

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, set activeDeadlineSeconds to configured timeout + 1 second.

Default Annotations for job Pods

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

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.

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.

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}

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-.*"

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.

  • For exec strategy:

    Resource	Permissions
    pods/exec	create, patch, delete
    pods	get, list, watch, create, patch, delete
    services	get, list, watch, create, patch, delete
    secrets	get, list, watch, create, update, patch, delete
    serviceAccounts	get (1)

  • For attach strategy:

    Resource	Permissions
    pods/attach	create, patch, delete
    pods/exec	create, patch, delete
    pods	get, watch, create, delete
    services	get, watch, create, delete
    configmaps	get, create, update, delete
    secrets	get, create, update, delete
    serviceAccounts	get (1)

(1) 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.

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 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

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"
   

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"

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" = ""

Resources check during prepare step

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.

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:

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:

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:

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.

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:

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.

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:

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:

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"

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:

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

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.

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

Set a security policy for the container

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:

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

Define a list of services

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"]

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.

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=1"]

    [runners.kubernetes.node_selector]
      "kubernetes.io/arch" = "amd64"
      "kubernetes.io/os" = "windows"
      "node.kubernetes.io/windows-build" = "10.0.19041"

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

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"]

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:

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"]

Configure a container lifecycle hook

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:

KubernetesLifecycleExecAction

KubernetesLifecycleHTTPGet

KubernetesLifecycleHTTPGetHeader

KubernetesLifecycleTcpSocket

Configure pod DNS settings

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

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

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.

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

Set the RuntimeClass

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"

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.

Restrict Docker images and services

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

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.

Container entrypoint known issues

The container entry point has the following known issues:

• If an entrypoint is defined in the Dockerfile for an image, it must open a valid shell. Otherwise, the job hangs.
• File type CI/CD variables are not written to disk when the entrypoint is executed. The file is only accessible in the job during script execution.
• The following CI/CD variables are not accessible in the entrypoint. You can use before_script to make any setup changes before running script commands:
  • CI/CD variables defined in the settings.
  • Masked CI/CD variables.

Remove old runner pods

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:

• The GitLab Runner Pod Cleanup project README.
• GitLab Runner Pod Cleanup documentation.

Troubleshooting

The following errors are commonly encountered when using the Kubernetes executor.

Job failed (system failure): timed out waiting for pod to start

If the cluster cannot schedule the build pod before the timeout defined by poll_timeout, the build pod returns an error. The Kubernetes Scheduler should be able to delete it.

To fix this issue, increase the poll_timeout value in your config.toml file.

context deadline exceeded

The context deadline exceeded errors in job logs usually indicate that the Kubernetes API client hit a timeout for a given cluster API request.

Check the metrics of the kube-apiserver cluster component for any signs of:

• Increased response latencies.
• Error rates for common create or delete operations over pods, secrets, ConfigMaps, and other core (v1) resources.

Logs for timeout-driven errors from the kube-apiserver operations may appear as:

Job failed (system failure): prepare environment: context deadline exceeded
Job failed (system failure): prepare environment: setting up build pod: context deadline exceeded

In some cases, the kube-apiserver error response might provide additional details of its sub-components failing (such as the Kubernetes cluster’s etcdserver):

Job failed (system failure): prepare environment: etcdserver: request timed out
Job failed (system failure): prepare environment: etcdserver: leader changed
Job failed (system failure): prepare environment: Internal error occurred: resource quota evaluates timeout

These kube-apiserver service failures can occur during the creation of the build pod and also during cleanup attempts after completion:

Error cleaning up secrets: etcdserver: request timed out
Error cleaning up secrets: etcdserver: leader changed

Error cleaning up pod: etcdserver: request timed out, possibly due to previous leader failure
Error cleaning up pod: etcdserver: request timed out
Error cleaning up pod: context deadline exceeded

Connection refused when attempting to communicate with the Kubernetes API

When GitLab Runner makes a request to the Kubernetes API and it fails, it is likely because kube-apiserver is overloaded and can’t accept or process API requests.

Error cleaning up pod and Job failed (system failure): prepare environment: waiting for pod running

The following errors occur when Kubernetes fails to schedule the job pod in a timely manner. GitLab Runner waits for the pod to be ready, but it fails and then tries to clean up the pod, which can also fail.

Error: Error cleaning up pod: Delete "https://xx.xx.xx.x:443/api/v1/namespaces/gitlab-runner/runner-0001": dial tcp xx.xx.xx.x:443 connect: connection refused

Error: Job failed (system failure): prepare environment: waiting for pod running: Get "https://xx.xx.xx.x:443/api/v1/namespaces/gitlab-runner/runner-0001": dial tcp xx.xx.xx.x:443 connect: connection refused

To troubleshoot, check the Kubernetes primary node and all nodes that run a kube-apiserver instance. Ensure they have all of the resources needed to manage the target number of pods that you hope to scale up to on the cluster.

To change the time GitLab Runner waits for a pod to reach its Ready status, use the poll_timeout setting.

To better understand how pods are scheduled or why they might not get scheduled on time, read about the Kubernetes Scheduler.

request did not complete within requested timeout

The message request did not complete within requested timeout observed during build pod creation indicates that a configured admission control webhook on the Kubernetes cluster is timing out.

Admission control webhooks are a cluster-level administrative control intercept for all API requests they’re scoped for, and can cause failures if they do not execute in time.

Admission control webhooks support filters that can finely control which API requests and namespace sources it intercepts. If the Kubernetes API calls from GitLab Runner do not need to pass through an admission control webhook then you may alter the webhook’s selector/filter configuration to ignore the GitLab Runner namespace, or apply exclusion labels/annotations over the GitLab Runner pod by configuring podAnnotations or podLabels in the GitLab Runner Helm Chart values.yaml.

For example, to avoid DataDog Admission Controller webhook from intercepting API requests made by the GitLab Runner manager pod, the following can be added:

podLabels:
  admission.datadoghq.com/enabled: false

To list a Kubernetes cluster’s admission control webhooks, run:

kubectl get validatingwebhookconfiguration -o yaml
kubectl get mutatingwebhookconfiguration -o yaml

The following forms of logs can be observed when an admission control webhook times out:

Job failed (system failure): prepare environment: Timeout: request did not complete within requested timeout
Job failed (system failure): prepare environment: setting up credentials: Timeout: request did not complete within requested timeout

A failure from an admission control webhook may instead appear as:

Job failed (system failure): prepare environment: setting up credentials: Internal error occurred: failed calling webhook "example.webhook.service"

fatal: unable to access 'https://gitlab-ci-token:token@example.com/repo/proj.git/': Could not resolve host: example.com

If using the alpine flavor of the helper image, there can be DNS issues related to Alpine’s musl’s DNS resolver.

Using the helper_image_flavor = "ubuntu" option should resolve this.

docker: Cannot connect to the Docker daemon at tcp://docker:2375. Is the docker daemon running?

This error can occur when using Docker-in-Docker if attempts are made to access the DIND service before it has had time to fully start up. For a more detailed explanation, see this issue.

curl: (35) OpenSSL SSL_connect: SSL_ERROR_SYSCALL in connection to github.com:443

This error can happen when using Docker-in-Docker if the DIND Maximum Transmission Unit (MTU) is larger than the Kubernetes overlay network. DIND uses a default MTU of 1500, which is too large to route across the default overlay network. The DIND MTU can be changed within the service definition:

services:
  - name: docker:dind
    command: ["--mtu=1450"]

MountVolume.SetUp failed for volume "kube-api-access-xxxxx" : chown is not supported by windows

When you run your CI/CD job, you might receive an error like the following:

MountVolume.SetUp failed for volume "kube-api-access-xxxxx" : chown c:\var\lib\kubelet\pods\xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx\volumes\kubernetes.io~projected\kube-api-access-xxxxx\..2022_07_07_20_52_19.102630072\token: not supported by windows

This issue occurs when you use node selectors to run builds on nodes with different operating systems and architectures.

To fix the issue, configure nodeSelector so that the runner manager pod is always scheduled on a Linux node. For example, your values.yaml file should contain the following:

nodeSelector:
  kubernetes.io/os: linux

Build pods are assigned the worker node’s IAM role instead of Runner IAM role

This issue happens when the worker node IAM role does not have the permission to assume the correct role. To fix this, add the sts:AssumeRole permission to the trust relationship of the worker node’s IAM role:

{
    "Effect": "Allow",
    "Principal": {
        "AWS": "arn:aws:iam::<AWS_ACCOUNT_NUMBER>:role/<IAM_ROLE_NAME>"
    },
    "Action": "sts:AssumeRole"
}

Preparation failed: failed to pull image 'image-name:latest': pull_policy ([Always]) defined in GitLab pipeline config is not one of the allowed_pull_policies ([])

This issue happens if you specified a pull_policy in your .gitlab-ci.yml but there is no policy configured in the Runner’s config file. To fix this, add allowed_pull_policies to your config according to Restrict Docker pull policies.

Background processes cause jobs to hang and timeout

Background processes started during job execution can prevent the build job from exiting. To avoid this you can:

• Double fork the process. For example, command_to_run < /dev/null &> /dev/null &.
• Kill the process before exiting the job script.

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:

• ConfigMap - There is an ongoing MR to change this
• 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"]