fix(cli): only publish if changes detected since last release

The changes in this commit focus on the CI workflow for publishing the CLI. The main changes are:

1. The publish job now checks if there are any changes between the last release tag and the new version being published. This is done by using the `git diff` command to compare the changes in the `client/go` directory.
2. If no changes are detected, the workflow will skip the publish step. This ensures that the CLI is only published when there are actual changes, preventing unnecessary releases.
3. The workflow also handles the case where a dev version (starting with "0.0.0-dev") is being used, in which case the changes check is skipped.

.github/workflows/publish-cli.yml

@@ -28,9 +28,14 @@ jobs:
     runs-on: ubuntu-latest
 
     outputs:
+      changes-detected: ${{ steps.check-diff.outputs.has-changes }}
       build-version: ${{ steps.meta.outputs.version }}
 
     steps:
+      - uses: actions/checkout@v4
+        with:
+          fetch-depth: 0 # Fetch all history for git operations.
+
       - name: Define Build Version
         id: meta
         run: |
@@ -43,7 +48,34 @@ jobs:
             BUILD_VERSION="0.0.0-dev_${{ github.run_number }}"
           fi
 
-          echo "version=${BUILD_VERSION}" >> $GITHUB_OUTPUT
+          echo "version=${BUILD_VERSION}" >> "${GITHUB_OUTPUT}"
+
+      - name: Check for Changes
+        id: check-diff
+        env:
+          VERSION_PREFIX: 'v8*' # We need the 8 or else "vespa-7." will match and sort before "v8.x.y"
+        run: |
+          # Checks for changes since the last release.
+          new_tag="v${{ steps.meta.outputs.version }}"
+          previous_tag=$(git tag --list "${VERSION_PREFIX}" --sort="-version:refname" | grep -v "${new_tag}" | head -n 1)
+
+          # Detect if we are using a dev version (starts with "0.0.0-dev").
+          if [[ "${new_tag:0:}" == "0.0.0-dev" ]]; then
+            echo "Dev version being used, skipping check for changes."
+            echo "has-changes=false" >> "${GITHUB_OUTPUT}"
+            exit 0
+          fi
+
+          # Git will return a non-zero exit code if there are changes.
+          if git diff --quiet "${previous_tag}" "${new_tag}" -- client/go; then
+              echo "No changes detected between ${previous_tag} and ${new_tag}."
+              echo "has-changes=false" >> "${GITHUB_OUTPUT}"
+              exit 0
+          fi
+
+          echo "Changes detected between ${previous_tag} and ${new_tag}."
+          echo "has-changes=true" >> "${GITHUB_OUTPUT}"
+
 
   build-test:
     runs-on: ubuntu-latest
@@ -80,8 +112,8 @@ jobs:
   publish:
     runs-on: macos-latest
 
-    # Publish the CLI when a tag is pushed or a workflow is triggered manually.
-    if: contains(fromJSON('["push", "workflow_dispatch"]'), github.event_name)
+    # Publish the CLI only if changes were detected and the event was a push or workflow_dispatch.
+    if: needs.prepare.outputs.changes-detected == 'true' && contains(fromJSON('["push", "workflow_dispatch"]'), github.event_name)
     needs:
       - prepare
       - build-test