Roseau Action

A GitHub Action that detects breaking changes between two versions of a Java library using Roseau.

Usage

jobs:
  api-compatibility:
    runs-on: ubuntu-latest
    permissions:
      pull-requests: write  # Required for PR comments
    steps:
      - uses: actions/checkout@v6
      - run: mvn --batch-mode -DskipTests package

      - uses: alien-tools/roseau-action@v1
        with:
          v1: com.example:my-lib:1.2.0
          v2: target/my-lib-1.3.0-SNAPSHOT.jar

Inputs

Input	Required	Default	Description
v1	yes		Baseline version: Maven coordinates (g:a:v), local JAR, or source directory
v2	yes		Current version: Maven coordinates (g:a:v), local JAR, or source directory
fail-on-bc	no	true	Fail the step if breaking changes are found
binary-only	no	false	Only report binary-breaking changes
source-only	no	false	Only report source-breaking changes
ignored	no		Path to a CSV file listing accepted breaking changes
comment	no	true	Post/update a PR comment with the report
reports	no		Comma-separated FORMAT=PATH pairs (e.g. HTML=report.html,CSV=report.csv)
classpath	no		Extra classpath JARs (colon-separated)
java-version	no	25	JDK version to set up
roseau-version	no	latest	Roseau release version (e.g. v0.6.0)

Outputs

Output	Description
has-breaking-changes	true or false
breaking-change-count	Number of breaking changes detected
report-path	Path to the generated JSON report

Examples

Compare a built JAR against the latest release

- uses: alien-tools/roseau-action@v1
  with:
    v1: com.example:my-lib:1.2.0
    v2: target/my-lib-1.3.0-SNAPSHOT.jar
    reports: HTML=roseau-report.html

Source-only check with accepted breaks

- uses: alien-tools/roseau-action@v1
  with:
    v1: com.example:my-lib:1.2.0
    v2: target/my-lib-1.3.0-SNAPSHOT.jar
    source-only: true
    ignored: .roseau/accepted-breaks.csv

Conditional steps based on results

- uses: alien-tools/roseau-action@v1
  id: roseau
  with:
    v1: com.example:my-lib:1.2.0
    v2: target/my-lib-1.3.0-SNAPSHOT.jar
    fail-on-bc: false

- if: steps.roseau.outputs.has-breaking-changes == 'true'
  run: echo "${{ steps.roseau.outputs.breaking-change-count }} breaking change(s) found"