ci: add PR/push workflow for testing the container image

Signed-off-by: László Várady <laszlo.varady@anno.io>

.github/workflows/axosyslog-image-test.yml

@@ -0,0 +1,65 @@
+name: CI @ AxoSyslog image
+
+on:
+  pull_request:
+  push:
+
+jobs:
+  tarball:
+    runs-on: ubuntu-latest
+    outputs:
+      snapshot-version: ${{ steps.snapshot-version.outputs.SNAPSHOT_VERSION }}
+    steps:
+      - name: Checkout AxoSyslog source
+        uses: actions/checkout@v4
+
+      - name: Prepare docker image
+        run: ./dbld/rules cache-image-tarball
+
+      - name: Create source tarball
+        run: ./dbld/rules pkg-tarball
+
+      - name: Determine snapshot version
+        id: snapshot-version
+        run: |
+          tarball_filename="$(find dbld/build -name '*.tar.*' -printf '%f\n')"
+          tarball_name="${tarball_filename/\.tar.*}"
+          tarball_version="${tarball_name/axosyslog-}"
+          pkg_version="$(echo $tarball_version | sed -E 's|(([0-9]+\.){2}[0-9]+).*|\1|')_git$(date +%Y%m%d)"
+          echo "SNAPSHOT_VERSION=${pkg_version}" >> $GITHUB_OUTPUT
+
+      - name: Store source tarball as artifact
+        uses: actions/upload-artifact@v4
+        with:
+          name: source-tarball
+          path: dbld/build/*.tar.gz
+
+  build-and-test:
+    runs-on: ubuntu-latest
+    needs: tarball
+    steps:
+      - name: Checkout AxoSyslog source
+        uses: actions/checkout@v4
+
+      - name: Download source tarball artifact
+        uses: actions/download-artifact@v4
+        with:
+          name: source-tarball
+          path: docker/apkbuild/axoflow/axosyslog
+
+      - name: Build Docker image
+        uses: docker/build-push-action@v5
+        with:
+          context: docker
+          file: docker/alpine.dockerfile
+          load: true
+          tags: axosyslog:test
+          build-args: |
+            PKG_TYPE=snapshot
+            SNAPSHOT_VERSION=${{ needs.tarball.outputs.snapshot-version }}
+
+      - name: Smoke test
+        run: |
+          export SYSLOG_NG_IMAGE="axosyslog:test"
+          export SYSLOG_NG_VERSION="${{ needs.tarball.outputs.snapshot-version }}"
+          docker/tests/smoke.sh