Where variables can be used

As it’s described in the CI/CD variables docs, you can define many different variables. Some of them can be used for all GitLab CI/CD features, but some of them are more or less limited.

This document describes where and how the different types of variables can be used.

Variables usage

There are two places defined variables can be used. On the:

  1. GitLab side, in .gitlab-ci.yml.
  2. The runner side, in config.toml.

.gitlab-ci.yml file

Definition Can be expanded? Expansion place Description
environment:url yes GitLab The variable expansion is made by GitLab’s internal variable expansion mechanism.<ul><li>Supported: all variables defined for a job (project/group variables, variables from .gitlab-ci.yml, variables from triggers, variables from pipeline schedules)</li><li>Not supported: variables defined in Runner’s config.toml and variables created in job’s script</li></ul>
environment:name yes GitLab Similar to environment:url, but the variables expansion doesn’t support: <ul><li>variables that are based on the environment’s name (CI_ENVIRONMENT_NAME, CI_ENVIRONMENT_SLUG)</li><li>any other variables related to environment (currently only CI_ENVIRONMENT_URL)</li><li>persisted variables</li></ul>
variables yes Runner The variable expansion is made by GitLab Runner’s internal variable expansion mechanism
image yes Runner The variable expansion is made by GitLab Runner’s internal variable expansion mechanism
services:[] yes Runner The variable expansion is made by GitLab Runner’s internal variable expansion mechanism
services:[]:name yes Runner The variable expansion is made by GitLab Runner’s internal variable expansion mechanism
cache:key yes Runner The variable expansion is made by GitLab Runner’s internal variable expansion mechanism
artifacts:name yes Runner The variable expansion is made by GitLab Runner’s shell environment
script, before_script, after_script yes Script execution shell The variable expansion is made by the execution shell environment
only:variables:[], except:variables:[] no n/a The variable must be in the form of $variable.
Not supported:<ul><li>variables that are based on the environment’s name (CI_ENVIRONMENT_NAME, CI_ENVIRONMENT_SLUG)</li><li>any other variables related to environment (currently only CI_ENVIRONMENT_URL)</li><li>persisted variables</li></ul>

config.toml file

Note: You can read more about config.toml in the Runner’s docs.
Definition Can be expanded? Description
runners.environment yes The variable expansion is made by the Runner’s internal variable expansion mechanism
runners.kubernetes.pod_labels yes The Variable expansion is made by the Runner’s internal variable expansion mechanism
runners.kubernetes.pod_annotations yes The Variable expansion is made by the Runner’s internal variable expansion mechanism

Expansion mechanisms

There are three expansion mechanisms:

  • GitLab
  • GitLab Runner
  • Execution shell environment

GitLab internal variable expansion mechanism

The expanded part needs to be in a form of $variable, or ${variable} or %variable%. Each form is handled in the same way, no matter which OS/shell will finally handle the job, since the expansion is done in GitLab before any Runner will get the job.

GitLab Runner internal variable expansion mechanism

  • Supported: project/group variables, .gitlab-ci.yml variables, config.toml variables, and variables from triggers, pipeline schedules, and manual pipelines.
  • Not supported: variables defined inside of scripts (e.g., export MY_VARIABLE="test").

The Runner uses Go’s os.Expand() method for variable expansion. It means that it will handle only variables defined as $variable and ${variable}. What’s also important, is that the expansion is done only once, so nested variables may or may not work, depending on the ordering of variables definitions.

Execution shell environment

This is an expansion that takes place during the script execution. How it works depends on the used shell (bash/sh/cmd/PowerShell). For example, if the job’s script contains a line echo $MY_VARIABLE-${MY_VARIABLE_2}, it should be properly handled by bash/sh (leaving empty strings or some values depending whether the variables were defined or not), but will not work with Windows’ cmd/PowerShell, since these shells are using a different variables syntax.

Supported:

  • The script may use all available variables that are default for the shell (e.g., $PATH which should be present in all bash/sh shells) and all variables defined by GitLab CI/CD (project/group variables, .gitlab-ci.yml variables, config.toml variables, and variables from triggers and pipeline schedules).
  • The script may also use all variables defined in the lines before. So, for example, if you define a variable export MY_VARIABLE="test":
    • In before_script, it will work in the following lines of before_script and all lines of the related script.
    • In script, it will work in the following lines of script.
    • In after_script, it will work in following lines of after_script.

Persisted variables

Note: Some of the persisted variables contain tokens and cannot be used by some definitions due to security reasons.

The following variables are known as “persisted”:

  • CI_PIPELINE_ID
  • CI_JOB_ID
  • CI_JOB_TOKEN
  • CI_BUILD_ID
  • CI_BUILD_TOKEN
  • CI_REGISTRY_USER
  • CI_REGISTRY_PASSWORD
  • CI_REPOSITORY_URL
  • CI_DEPLOY_USER
  • CI_DEPLOY_PASSWORD

They are:

Variables with an environment scope

Variables defined with an environment scope are supported. Given that there is a variable $STAGING_SECRET defined in a scope of review/staging/*, the following job that is using dynamic environments is going to be created, based on the matching variable expression:

my-job:
  stage: staging
  environment:
    name: review/$CI_JOB_STAGE/deploy
  script:
    - 'deploy staging'
  only:
    variables:
      - $STAGING_SECRET == 'something'