Can't set "never" as an environment auto_stop_in value

Summary

The documentation for the CI environment "auto-stop" feature indicates that "auto_stop_in uses the same format of artifacts:expire_in docs".

However "never" is not a valid option, despite being clearly listed as valid in the artifacts:expire_in documentation.

This means that the "obvious" way to create persistent environments - setting auto_stop_in to "never" - doesn't work.

(I understand that you're supposed to use protected environments for production environments, but that's less discoverable if you're looking at environments from the CI YAML reference.)

Documentation links:

• CI YAML reference for environment:auto_stop_in: https://docs.gitlab.com/ee/ci/yaml/#environmentauto_stop_in
• Environment reference for the "auto-stop" feature: https://docs.gitlab.com/ee/ci/environments/index.html#environments-auto-stop
• CI YAML reference for artifacts:expire_in: https://docs.gitlab.com/ee/ci/yaml/README.html#artifactsexpire_in
• Protected environments: https://docs.gitlab.com/ee/ci/environments/protected_environments.html

Steps to reproduce

Example .gitlab-ci.yml file:

deploy_persistent:
  script:
    - echo "deploy the thing"

  environment:
    name: persistent-environment
    auto_stop_in: never

1. Define a pipeline job with an environment that should be persistent
2. Set environment:auto_stop_in to "never"
3. Lint the CI script

Example Project

I have not created an example project as the issue can be reproduced with the CI Linter in any project.

What is the current bug behavior?

The current behaviour is that the linting fails with the error:

jobs:deploy_persistent:environment auto stop in should be a duration

What is the expected correct behavior?

According to the documentation, "never" should be a valid duration and therefore the linting should succeed.

I'd expect that an environment created by a job with auto_stop_in set to "never" would have no "auto stop in" time set, identically to what would happen if the "pin" button had been pressed.

Relevant logs and/or screenshots

gitlab-ci-environment-auto_stop_in-never-bug

Output of checks

This bug happens on GitLab.com.

Possible fixes

When the "environment:auto_stop_in" key was added it was set to be a "duration" type value: !19931 (diffs) (Current code: https://gitlab.com/gitlab-org/gitlab/-/blob/master/lib/gitlab/ci/config/entry/environment.rb#L52) However the "artifacts:expire_in" key uses it's own custom parser: https://gitlab.com/gitlab-org/gitlab/-/blob/master/lib/gitlab/ci/config/entry/artifacts.rb#L45

I suspect that the correct fix here is for the environment:auto_stop_in key to use the same parser and logic as the artifacts:expire_in key.

However it's also possible that this particular feature - creating environments without an expiry time - is unwanted and the protected environment feature should be used instead, in which case the correct solution here is to update the documentation to make it explicit that environment:auto_stop_in must be a duration and "never" isn't allowed.

Proposal

Allow a user to define when: neveras part of auto-stop in