ci: integrate oasdiff to detect breaking API changes

Automatically detect breaking changes in the API by running oasdiff in
CI. The build will fail if any breaking changes are detected, ensuring
API stability.

Reference: https://github.com/Tufin/oasdiff

Signed-off-by: Michael Adler <michael.adler@siemens.com>

Author: michaeladler

.github/workflows/ci.yml

@@ -262,6 +262,19 @@ jobs:
       - run: just generate
       - run: git diff --exit-code
 
+  openapi-check-breaking:
+    name: API check
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4
+      - name: Check for breaking changes in API
+        id: breaking_changes
+        uses: oasdiff/oasdiff-action/breaking@v0.0.21
+        with:
+          base: https://raw.githubusercontent.com/siemens/wfx/refs/heads/main/spec/wfx.openapiv3.yml
+          revision: spec/wfx.openapiv3.yml
+          fail-on: ERR
+
   release:
     name: Release
     if: startsWith(github.event.ref, 'refs/tags/v')
@@ -280,6 +293,7 @@ jobs:
       - lint
       - reuse
       - generate
+      - openapi-check-breaking
     steps:
       - name: Checkout
         uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4