Add AND and OR operators for variable expressions in GitLab CI/CD

Problem to solve

only/except are powerful primitives, but today are limited to only one case - either a single condition such as

job:
  # use regexp
  only:
    - /^issue-.*$/
  # use special keyword
  except:
    - branches

Adding multiple items does an "implied OR" such that

job:
  # use regexp
  only:
    - /^issue-.*$/
    - master

Will build on branches that match the RegEx OR the master branch

Intended users

• Persona: DevOps Engineer
• Persona: Development Team Lead

Further details

This will be an excellent iteration for more complex use cases for only/expect, but will not be as wide of a solution as the flexible ruleset. Both will have impacts on how users can control which jobs run when, but have points where both are useful

Proposal

Allow a user to specific AND and OR conditions explicitly in a variable expression.

Use a well-known pattern of && for AND and || for OR. This will produce the ability for use cases such as:

Run on a job on master - AND on tags

job:
  stage: publish
  script:
    - ./do-publish.sh  
  only:
    - tags && master

Run a job on based on two different variables

  only:
    - $VARIABLE1 =~ /^content.*/ || $VARIABLE2 =~ /thing$/

Complex logic with AND and OR

  only:
    - $VARIABLE1 =~ /^content.*/ || $VARIABLE2 =~ /thing$/ && $VARIABLE3

Permissions and Security

This will not change anything about the permissions or security for variables or the .gitlab-ci.yml

Documentation

This will require a documentation update with details AND clear examples.

Testing

What does success look like, and how can we measure that?

Links / references