Feature flags

Introduced in GitLab 11.4.

Feature flags are toggles that allow you to enable or disable specific features. These flags are typically used:

  • For beta features that are made available for volunteers to test, but that are not ready to be enabled for all users.

    Beta features are sometimes incomplete or need further testing. A user who wants to use a beta feature can choose to accept the risk and explicitly enable the feature with a feature flag. Other users who do not need the feature or who are not willing to accept the risk on their system have the feature disabled by default and are not impacted by possible bugs and regressions.

  • For breaking changes that result in functionality deprecation or feature removal in the near future.

    As the product evolves, features are sometimes changed or removed entirely. Known bugs are often fixed, but in some cases, users have already found a workaround for a bug that affected them; forcing users to adopt the standardized bug fix might cause other problems with their customized configurations.

    In such cases, the feature flag is used to switch from the old behavior to the new one on demand. This allows users to adopt new versions of the product while giving them time to plan for a smooth, permanent transition from the old behavior to the new behavior.

Feature flags are toggled using environment variables. To:

  • Activate a feature flag, set the corresponding environment variable to "true" or 1.
  • Deactivate a feature flag, set the corresponding environment variable to "false" or 0.

Available feature flags

Feature flag Default value Deprecated To be removed with Description
FF_CMD_DISABLE_DELAYED_ERROR_LEVEL_EXPANSION false   Disables EnableDelayedExpansion for error checking for when using Window Batch shell
FF_NETWORK_PER_BUILD false   Enables creation of a Docker network per build with the docker executor
FF_USE_LEGACY_KUBERNETES_EXECUTION_STRATEGY false   When set to false disables execution of remote Kubernetes commands through exec in favor of attach to solve problems like #4119
FF_USE_DIRECT_DOWNLOAD true   When set to true Runner tries to direct-download all artifacts instead of proxying through GitLab on a first try. Enabling might result in a download failures due to problem validating TLS certificate of Object Storage if it is enabled by GitLab. See Self-signed certificates or custom Certification Authorities
FF_SKIP_NOOP_BUILD_STAGES true   When set to false all build stages are executed even if running them has no effect
FF_USE_FASTZIP false   Fastzip is a performant archiver for cache/artifact archiving and extraction
FF_GITLAB_REGISTRY_HELPER_IMAGE true   Use GitLab Runner helper image for the Docker and Kubernetes executors from registry.gitlab.com instead of Docker Hub
FF_DISABLE_UMASK_FOR_DOCKER_EXECUTOR false   If enabled will remove the usage of umask 0000 call for jobs executed with docker executor. Instead Runner will try to discover the UID and GID of the user configured for the image used by the build container and will change the ownership of the working directory and files by running the chmod command in the predefined container (after updating sources, restoring cache and downloading artifacts). POSIX utility id must be installed and operational in the build image for this feature flag. Runner will execute id with options -u and -g to retrieve the UID and GID.
FF_ENABLE_BASH_EXIT_CODE_CHECK false   If enabled, bash scripts don’t rely solely on set -e, but check for a non-zero exit code after each script command is executed.
FF_USE_WINDOWS_LEGACY_PROCESS_STRATEGY true   When disabled, processes that Runner creates on Windows (shell and custom executor) will be created with additional setup that should improve process termination. This is currently experimental and how we setup these processes may change as we continue to improve this. When set to true, legacy process setup is used. To successfully and gracefully drain a Windows Runner, this feature flag shouldbe set to false.
FF_SKIP_DOCKER_MACHINE_PROVISION_ON_CREATION_FAILURE true   With the docker+machine executor, when a machine is not created, docker-machine provision runs for X amount of times. When this feature flag is set to true, it skips docker-machine provision, removes the machine, and creates another machine instead.
FF_USE_NEW_BASH_EVAL_STRATEGY false   When set to true, the Bash eval call is executed in a subshell to help with proper exit code detection of the script executed.
FF_USE_POWERSHELL_PATH_RESOLVER false   When enabled, Powershell resolves pathnames rather than Runner using OS-specific filepath functions that are specific to where Runner is hosted.

Enable feature flag in pipeline configuration

You can use CI variables to enable feature flags:

  • For all jobs in the pipeline (globally):

    variables:
      FEATURE_FLAG_NAME: 1
    
  • For a single job:

    job:
      stage: test
      variables:
        FEATURE_FLAG_NAME: 1
      script:
      - echo "Hello"
    

Enable feature flag in runner environment variables

To enable the feature for every job a Runner runs, specify the feature flag as an environment variable in the Runner configuration:

[[runners]]
  name = "ruby-2.6-docker"
  url = "https://CI/"
  token = "TOKEN"
  limit = 0
  executor = "docker"
  builds_dir = ""
  shell = ""
  environment = ["FEATURE_FLAG_NAME=1"]

Enable feature flag in runner configuration

Introduced in GitLab Runner 13.11.

You can enable feature flags by specifying them under [runners.feature_flag]. This setting prevents any job from overriding the feature flag values.

Some feature flags are also only usable when you configure this setting, because they don’t deal with how the job is executed.

[[runners]]
  name = "ruby-2.6-docker"
  url = "https://CI/"
  token = "TOKEN"
  executor = "docker"
  [runners.feature_flags]
    FF_USE_DIRECT_DOWNLOAD = true