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---
# CI/CD YAML reference style guide
The CI/CD YAML reference uses a standard style to make it easier to use and update.
The reference information should be kept as simple as possible, and expanded details
and examples documented in a separate page.
## YAML reference structure
Every YAML keyword must have its own section in the reference. The sections should
be nested so that the keywords follow a logical tree structure. For example:
```plaintext
### `artifacts`
#### `artifacts:name`
#### `artifacts:paths`
#### `artifacts:reports`
##### `artifacts:reports:dast`
##### `artifacts:reports:sast`
```
## YAML reference style
Each keyword entry in the reference should use the following style:
````markdown
### `keyword-name`
> Version information
Keyword description and main details.
**Keyword type**:
**Possible inputs**:
**Example of `keyword-name`**:
(optional) In this example...
(optional) **Additional details**:
- List of extra details.
(optional) **Related topics**:
- List of links to topics related to the keyword.
````
- ``### `keyword-name` ``: The keyword name must always be in backticks.
If it is a subkey of another keyword, write out all the keywords, with each separated
by `:`, for example: `artifacts:reports:dast`.
- ``> Version information``: The [version history details](../documentation/styleguide/index.md#version-text-in-the-version-history).
If the keyword is feature flagged, see the [feature flag documentation guide](../documentation/feature_flags.md)
as well.
-`Keyword description and main details.`: A simple description of the keyword, and
how to use it. Additional use cases and benefits should be added to a page outside
the reference document. Link to that document in this section.
-`**Keyword type**:`: Most keywords are defined at the job level, like `script`,
or at the pipeline level, like `stages`. Add the appropriate line:
-`**Keyword type**: Job keyword. You can use it only as part of a job.`
-`**Keyword type**: Pipeline keyword. You cannot use it as part of a job.`
If a keyword can be used at both the job and pipeline level, like `variables`,
explain it in detail instead of using the pre-written lines above.
-`**Possible inputs**:`: Explain in detail which inputs the keyword can accept.
You can add the details in a sentence, paragraph, or list.
- ``**Example of `keyword-name`**:``: An example configuration that uses the keyword.
Do not add extra keywords that are not required to understand the behavior.
- (optional) `In this example...`: If the example needs extra details,
add the clarification text below the example.
- (optional) `**Additional details**:` If there are any caveats or extra details you
want to document along with the keyword, add each one as a list item here.
- (optional) `**Related topics**:` If there are any other keywords or pages that
relate to this keyword, add these links as list items here.
### YAML reference style example
See the [`only:changes` / `except:changes`](../../ci/yaml/README.md#onlychanges--exceptchanges)
documentation for an example of the YAML reference style. The following example is a
shortened version of that documentation's Markdown:
````markdown
#### `only:changes` / `except:changes`
> [Introduced](https://gitlab.com/gitlab-org/gitlab-foss/-/issues/19232) in GitLab 11.4.
Use the `changes` keyword with `only` to run a job, or with `except` to skip a job,
when a Git push event modifies a file.
Use `changes` in pipelines with the following refs:
-`branches`
-`external_pull_requests`
-`merge_requests` (see additional details about [using `only:changes` with pipelines for merge requests](../jobs/job_control.md#use-onlychanges-with-pipelines-for-merge-requests))
**Keyword type**: Job keyword. You can use it only as part of a job.
**Possible inputs**: An array including any number of:
- Paths to files.
- Wildcard paths for single directories, for example `path/to/directory/*`, or a directory
and all its subdirectories, for example `path/to/directory/**/*`.
In this example, `docker build` only runs in branch pipelines, and only if at least one of
these files changed:
-`Dockerfile`.
- Any file in `docker/scripts`
- Any file in `dockerfiles/` or any of its subdirectories.
**Additional details**:
- If you use refs other than `branches`, `external_pull_requests`, or `merge_requests`,
`changes` can't determine if a given file is new or old and always returns `true`.
- If you use `only: changes` with other refs, jobs ignore the changes and always run.
- If you use `except: changes` with other refs, jobs ignore the changes and never run.
**Related topics**:
- [`only: changes` and `except: changes` examples](../jobs/job_control.md#onlychanges--exceptchanges-examples).
- If you use `changes` with [only allow merge requests to be merged if the pipeline succeeds](../../user/project/merge_requests/merge_when_pipeline_succeeds.md#only-allow-merge-requests-to-be-merged-if-the-pipeline-succeeds),
you should [also use `only:merge_requests`](../jobs/job_control.md#use-onlychanges-with-pipelines-for-merge-requests).
- Use `changes` with [scheduled pipelines](../jobs/job_control.md#use-onlychanges-with-scheduled-pipelines).
