# Where variables can be used
As it's described in the [CI/CD variables](README.md) 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`.
1. 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](#gitlab-internal-variable-expansion-mechanism).
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 Runner's `config.toml` and variables created in job's `script`. |
| `environment:name` | yes | GitLab | Similar to `environment:url`, but the variables expansion doesn't support the following:
- Variables that are based on the environment's name (`CI_ENVIRONMENT_NAME`, `CI_ENVIRONMENT_SLUG`).
- Any other variables related to environment (currently only `CI_ENVIRONMENT_URL`).
- [Persisted variables](#persisted-variables). |
| `variables` | yes | Runner | The variable expansion is made by GitLab Runner's [internal variable expansion mechanism](#gitlab-runner-internal-variable-expansion-mechanism) |
| `image` | yes | Runner | The variable expansion is made by GitLab Runner's [internal variable expansion mechanism](#gitlab-runner-internal-variable-expansion-mechanism) |
| `services:[]` | yes | Runner | The variable expansion is made by GitLab Runner's [internal variable expansion mechanism](#gitlab-runner-internal-variable-expansion-mechanism) |
| `services:[]:name` | yes | Runner | The variable expansion is made by GitLab Runner's [internal variable expansion mechanism](#gitlab-runner-internal-variable-expansion-mechanism) |
| `cache:key` | yes | Runner | The variable expansion is made by GitLab Runner's [internal variable expansion mechanism](#gitlab-runner-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](#execution-shell-environment) |
| `only:variables:[]`, `except:variables:[]` | no | n/a | The variable must be in the form of `$variable`. Not supported are the following:
- Variables that are based on the environment's name (`CI_ENVIRONMENT_NAME`, `CI_ENVIRONMENT_SLUG`).
- Any other variables related to environment (currently only `CI_ENVIRONMENT_URL`).
- [Persisted variables](#persisted-variables). |
### `config.toml` file
NOTE: **Note:**
You can read more about `config.toml` in the [Runner's docs](https://docs.gitlab.com/runner/configuration/advanced-configuration.html).
| Definition | Can be expanded? | Description |
|:-------------------------------------|:-----------------|:---------------------------------------------------------------------------------------------------------------------------------------------|
| `runners.environment` | yes | The variable expansion is made by the Runner's [internal variable expansion mechanism](#gitlab-runner-internal-variable-expansion-mechanism) |
| `runners.kubernetes.pod_labels` | yes | The Variable expansion is made by the Runner's [internal variable expansion mechanism](#gitlab-runner-internal-variable-expansion-mechanism) |
| `runners.kubernetes.pod_annotations` | yes | The Variable expansion is made by the Runner's [internal variable expansion mechanism](#gitlab-runner-internal-variable-expansion-mechanism) |
## Expansion mechanisms
There are three expansion mechanisms:
- GitLab
- GitLab Runner
- Execution shell environment
### GitLab internal variable expansion mechanism
The expanded part needs to be in a form of `$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: **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:
- Supported for definitions where the ["Expansion place"](#gitlab-ciyml-file) is:
- Runner.
- Script execution shell.
- Not supported:
- For definitions where the ["Expansion place"](#gitlab-ciyml-file) is GitLab.
- In the `only` and `except` [variables expressions](README.md#environment-variables-expressions).