get-changes-action

This is a GitHub action that allows you to conditionally run workflow steps based on changes between commits. It is entirely based on a bash script and has no dependencies.

Why run your entire test suite when all you did was change a line in your README?

Example

- id: changes
  uses: ./
  with:
    filters: |
      py: .py

  # Run this step only if there are changes to files matching .py
- if: ${{ fromJson(steps.changes.outputs.result).py == 'true' }}
  run: ...

How it works

The action compares two commits/features with git diff --name-only <base>..<commit>. Then it loops through the filters and grep for matching changes.

grep is done with the -E flag, meaning that the filters should be specified using the extended regex syntax (ERE)

grep documentation for basic vs extended can be seen here

Use the github action expression fromJson to access the result.

Options

uses: ivarflakstad/get-changes-action
with:
  # The commit SHA, branch name, or tag that specifies the base of comparison
  # Defaults to 'origin/main'
  base:

  # The commit SHA, branch name, or tag that specifies that will be compared
  # against 'base'
  # Defaults to 'HEAD'
  commit:
    
  # The first depth of 'git fetch' used on 'base'.
  # The action will iteratively deepen the fetch by 100 until 'git merge-base' 
  # finds a common ancestor(s).
  # Defaults to '0' - which will fetch all remotes.
  fetch_depth:
  
  # Filters to match against 'git diff --name-only <base>..<commit>'
  # Uses grep with extended regex syntax.
  filters:

outputs:
  # JSON containing the matched changes.
  # Example:
  # {
  #   "has_any_changes":"true",
  #   "md":"true",
  #   "md_files":["README.md"],
  #   "md_count":1,
  #   "changes":["md"]
  # }
  # Use github action's `fromJson` expression to access the result:
  # - if: ${{ fromJson(steps.changes.outputs.result).md == 'true' }}
  result: