add path check to gha (open-telemetry#1052)

* add path check to gha

* get path from dockerfile

* fix lint

* override skip on push

* remove set_output usages

* fix lint

* fix

---------

Co-authored-by: Carter Socha <43380952+cartersocha@users.noreply.github.com>
Co-authored-by: Juliano Costa <julianocosta89@outlook.com>

.github/workflows/build-images.yml

@@ -1,6 +1,11 @@
 # Copyright The OpenTelemetry Authors
 # SPDX-License-Identifier: Apache-2.0
+
 on:
+  push:
+    paths:
+      - 'src/**'
+      - 'test/**'
   workflow_call:
     inputs:
       push:
@@ -93,35 +98,48 @@ jobs:
       - uses: actions/checkout@v3
         with:
           fetch-depth: 0
-
+      - name: Check for file changes
+        id: check_changes
+        if: ${{ !inputs.push }}
+        run: |
+          DOCKERFILE_DIR=$(dirname ${{ matrix.file_tag.file }})
+          FILES_CHANGED=$(git diff --name-only ${{ github.event.before }} ${{ github.sha }} -- $DOCKERFILE_DIR)
+          if [ -z "$FILES_CHANGED" ]; then
+            echo "No changes in ${{ matrix.file_tag.context }}, skipping build."
+            echo "skip=true >> $GITHUB_OUTPUT"
+          else
+            echo "Changes detected in ${{ matrix.file_tag.context }}, proceeding with build."
+            echo "skip=false >> $GITHUB_OUTPUT"
+          fi
+      - name: Override skip for push
+        if: ${{ inputs.push }}
+        run: echo "skip=false >> $GITHUB_OUTPUT"
+        id: override_skip
       - name: Log in to the Container registry
         uses: docker/#-action@v2
         with:
           registry: ghcr.io
           username: ${{ github.repository_owner }}
           password: ${{ secrets.GITHUB_TOKEN }}
         if: ${{ inputs.push }}
-
       - name: Log in to Docker Hub
         uses: docker/#-action@v2
         with:
           username: ${{ secrets.DOCKER_USERNAME }}
           password: ${{ secrets.DOCKER_PASSWORD }}
         if: ${{ inputs.push }}
-
       - name: Set up QEMU
         uses: docker/setup-qemu-action@v2
         with:
           image: tonistiigi/binfmt:master
-
       - name: Set up Docker Buildx
         uses: docker/setup-buildx-action@v2
         with:
           config-inline: |
             [worker.oci]
-              max-parallelism = 2
-
+            max-parallelism = 2
       - name: Matrix Build and push demo images
+        if: steps.check_changes.outputs.skip == 'false' || steps.override_skip.outputs.skip == 'false'
         uses: docker/build-push-action@v3.3.1
         with:
           context: ${{ matrix.file_tag.context }}