ci: fix and document CI

.github/workflows/docker.yml

@@ -1,26 +1,26 @@
 name: Docker CI
-on: [push]
+
+concurrency:
+  group: docker-${{ github.ref }}
+  cancel-in-progress: true
+
+on: [push, workflow_dispatch]
+
+env:
+  BUILDKIT_VERSION: 'v0.29.0'
+
 jobs:
-  build:
+  docker-build:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v5
-      - uses: docker/setup-buildx-action@v1
-      - uses: actions/cache@v4
+      - name: Checkout repository
+        uses: actions/checkout@v6
+      - name: Set up buildkit cache
+        uses: actions/cache@v4
         with:
-          path: /tmp/.buildx-cache
-          key: ${{ runner.os }}-buildx-${{ github.sha }}
-          restore-keys: |
-            ${{ runner.os }}-buildx-
-      - uses: docker/build-push-action@v2
+          path: /var/lib/buildkit
+          key: ${{ runner.os }}-buildkit-${{ env.BUILDKIT_VERSION }}
+      - name: Test docker build
+        uses: klemek/dockerfile-test-build@v1
         with:
-          context: ./
-          file: ./Dockerfile
-          builder: ${{ steps.buildx.outputs.name }}
-          push: false
-          cache-from: type=local,src=/tmp/.buildx-cache
-          cache-to: type=local,dest=/tmp/.buildx-cache-new
-      - run: |
-          rm -rf /tmp/.buildx-cache
-          mv /tmp/.buildx-cache-new /tmp/.buildx-cache
-      - run: echo ${{ steps.docker_build.outputs.digest }}
+          buildkit_version: ${{ env.BUILDKIT_VERSION }}