Where variables can be used

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As it's described in the CI/CD variables documentation, 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 the .gitlab-ci.yml file.
2. The GitLab Runner side, in config.toml.

.gitlab-ci.yml file

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• Support for CI_ENVIRONMENT_* variables except CI_ENVIRONMENT_SLUG introduced in GitLab 16.4.

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• CI_ENVIRONMENT_* variables.
• Persisted variables. | | environment:url | yes | GitLab | The variable expansion is made by the internal variable expansion mechanism in GitLab.

Supported are all variables defined for a job (project/group variables, variables from .gitlab-ci.yml, variables from triggers, variables from pipeline schedules).

Not supported are variables defined in the GitLab Runner config.toml and variables created in the job's script. | | environment:deployment_tier | yes | GitLab | Similar to environment:url, but the variables expansion doesn't support the following:

• CI_ENVIRONMENT_* variables.
• Persisted variables. | | environment:auto_stop_in | yes | GitLab | The variable expansion is made by the internal variable expansion mechanism in GitLab.

The value of the variable being substituted should be a period of time in a human readable natural language form. See supported values for more information. | | environment:kubernetes:agent | yes | GitLab | Similar to environment:url, but the variables expansion does not support the following:

• CI_ENVIRONMENT_* variables.

• Persisted variables. | | environment:kubernetes:namespace | yes | GitLab | Similar to environment:url, but the variables expansion does not support the following:

• CI_ENVIRONMENT_* variables.

• Persisted variables. | | id_tokens:aud | yes | GitLab | The variable expansion is made by the internal variable expansion mechanism in GitLab. Variable expansion introduced in GitLab 16.1. | | image | yes | Runner | The variable expansion is made by GitLab Runner's internal variable expansion mechanism. | | include | yes | GitLab | The variable expansion is made by the internal variable expansion mechanism in GitLab.

See Use variables with include for more information on supported variables. | | resource_group | yes | GitLab | Similar to environment:url, but the variables expansion doesn't support the following:

• CI_ENVIRONMENT_URL

• Persisted variables. | | rules:changes | no | GitLab | The variable expansion is made by the internal variable expansion mechanism in GitLab. | | rules:changes:compare_to | no | GitLab | The variable expansion is made by the internal variable expansion mechanism in GitLab. | | rules:exists | no | GitLab | The variable expansion is made by the internal variable expansion mechanism in GitLab. | | rules:if | no | Not applicable | The variable must be in the form of $variable. Not supported are the following:

• CI_ENVIRONMENT_SLUG variable.

• Persisted variables. | | script | yes | Script execution shell | The variable expansion is made by the execution shell environment. | | services:name | yes | Runner | The variable expansion is made by GitLab Runner's internal variable expansion mechanism. | | tags | yes | GitLab | The variable expansion is made by the internal variable expansion mechanism in GitLab. | | trigger and trigger:project | yes | GitLab | The variable expansion is made by the internal variable expansion mechanism in GitLab. Variable expansion for trigger:project introduced in GitLab 15.3. | | variables | yes | GitLab/Runner | The variable expansion is first made by the internal variable expansion mechanism in GitLab, and then any unrecognized or unavailable variables are expanded by GitLab Runner's internal variable expansion mechanism. | | workflow:name | yes | GitLab | The variable expansion is made by the internal variable expansion mechanism in GitLab.

Supported are all variables available in workflow:

• Project/Group variables.
• Global variables and workflow:rules:variables (when matching the rule).
• Variables inherited from parent pipelines.
• Variables from triggers.
• Variables from pipeline schedules.

Not supported are variables defined in the GitLab Runner config.toml, variables defined in jobs, or Persisted variables. |

config.toml file

You can read more about config.toml in the GitLab Runner docs.

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 handles the job, because the expansion is done in GitLab before any runner gets the job.

Nested variable expansion

GitLab expands job variable values recursively before sending them to the runner. For example, in the following scenario:

- BUILD_ROOT_DIR: '${CI_BUILDS_DIR}'
- OUT_PATH: '${BUILD_ROOT_DIR}/out'
- PACKAGE_PATH: '${OUT_PATH}/pkg'

The runner receives a valid, fully-formed path. For example, if ${CI_BUILDS_DIR} is /output, then PACKAGE_PATH would be /output/out/pkg.

References to unavailable variables are left intact. In this case, the runner attempts to expand the variable value at runtime. For example, a variable like CI_BUILDS_DIR is known by the runner only at runtime.

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 (for example, export MY_VARIABLE="test").

The runner uses Go's os.Expand() method for variable expansion. It means that it handles 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, and whether nested variable expansion is enabled in GitLab.

For artifacts and cache uploads, the runner uses mvdan.cc/sh/v3/expand for variable expansion instead of Go's os.Expand() because mvdan.cc/sh/v3/expand supports parameter expansion.

Execution shell environment

This is an expansion phase that takes place during the script execution. Its behavior depends on the shell used (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 don't work with Windows' cmd or PowerShell, because these shells use a different variables syntax.

Supported:

• The script may use all available variables that are default for the shell (for example, $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 works in the subsequent lines of before_script and all lines of the related script.
  • In script, it works in the subsequent lines of script.
  • In after_script, it works in subsequent lines of after_script.

In the case of after_script scripts, they can:

• Only use variables defined before the script within the same after_script section.
• Not use variables defined in before_script and script.

These restrictions exist because after_script scripts are executed in a separated shell context.

Persisted variables

Some predefined variables are called persisted. Persisted variables are:

• Supported for definitions where the expansion place is:
  • Runner.
  • Script execution shell.
• Not supported:
  • For definitions where the expansion place is GitLab.
  • In rules variables expressions.

Pipeline trigger jobs cannot use job-level persisted variables, but can use pipeline-level persisted variables.

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

Pipeline-level persisted variables:

• CI_PIPELINE_ID
• CI_PIPELINE_URL

Job-level persisted variables:

• CI_DEPLOY_PASSWORD
• CI_DEPLOY_USER
• CI_JOB_ID
• CI_JOB_STARTED_AT
• CI_JOB_TOKEN
• CI_JOB_URL
• CI_PIPELINE_CREATED_AT
• CI_REGISTRY_PASSWORD
• CI_REGISTRY_USER
• CI_REPOSITORY_URL

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 created, based on the matching variable expression:

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