chore(ci): use `docker/metadata-action` (#756)

* chore(ci): use `docker/metadata-action`

- Replace custom `setup-image-vars` action by `docker/metadata-action`
- Automatically add latest tag on semver tag

Signed-off-by: Ronny Moreas <ronny.moreas@kuleuven.be>

* chore(ci): add image tag on PR

Signed-off-by: Ronny Moreas <ronny.moreas@kuleuven.be>

* chore(ci): cleanup trailing spaces

Signed-off-by: Ronny Moreas <ronny.moreas@kuleuven.be>

* chore(ci): remove `setup-image-vars` action

Signed-off-by: Ronny Moreas <ronny.moreas@kuleuven.be>

---------

Signed-off-by: Ronny Moreas <ronny.moreas@kuleuven.be>

.github/actions/setup-image-vars/action.yaml

@@ -1,35 +0,0 @@
-name: "Setup Image Variables"
-
-inputs:
-  dockerfile:
-    required: true
-
-outputs:
-  tag:
-    description: "The tag if run against a tag, otherwise 'canary'"
-    value: ${{ steps.vars.outputs.tag }}
-  suffix:
-    description: "The suffix for the image package name (if any)"
-    value: ${{ steps.vars.outputs.suffix }}
-
-runs:
-  using: "composite"
-  steps:
-    - name: Get reference and suffix
-      id: vars
-      shell: bash
-      env:
-        DOCKERFILE: ${{ inputs.dockerfile }}
-      run: |
-        TAG=${GITHUB_REF##*/}
-        if [[ $GITHUB_REF == refs/heads/main ]]; then
-            TAG=canary
-        elif [[ $GITHUB_REF == refs/pull/*/merge ]]; then
-            TAG=pullrequest  # this 'tag' is just used for caching
-        fi
-        echo ::set-output name=tag::${TAG:-canary}
-        SUFFIX=${DOCKERFILE##Dockerfile}
-        if [[ "${SUFFIX}" == "."* ]]; then
-            SUFFIX=${SUFFIX//./-}  # convert dots into dashes
-        fi
-        echo ::set-output name=suffix::${SUFFIX}

.github/workflows/images.yaml

@@ -30,10 +30,13 @@ jobs:
       packages: write
     strategy:
       matrix:
-        dockerfile:
-          - Dockerfile
-          - Dockerfile.debian-stable-slim
-          - Dockerfile.ubuntu
+        image:
+          - dockerfile: Dockerfile
+            suffix: ""
+          - dockerfile: Dockerfile.debian-stable-slim
+            suffix: "-debian-stable-slim"
+          - dockerfile: Dockerfile.ubuntu
+            suffix: "-ubuntu"
     steps:
       - name: Checkout
         uses: actions/checkout@v3
@@ -48,11 +51,16 @@ jobs:
         with:
           version: latest
 
-      - name: Set up Image Variables
-        id: vars
-        uses: ./.github/actions/setup-image-vars
+      - name: Docker meta
+        id: meta
+        uses: docker/metadata-action@v4
         with:
-          dockerfile: ${{ matrix.dockerfile }}
+          images: ghcr.io/${{ github.repository }}${{ matrix.image.suffix }}
+          flavor: latest=true
+          tags: |
+            type=raw,value=canary,enable=${{ github.ref == format('refs/heads/{0}', 'main') }}
+            type=ref,event=pr
+            type=semver,pattern={{raw}}
 
       - name: Login to GitHub Container Registry
         uses: docker/login-action@v1
@@ -65,10 +73,10 @@ jobs:
         uses: docker/build-push-action@v3
         with:
           context: .
-          file: ${{ matrix.dockerfile }}
+          file: ${{ matrix.image.dockerfile }}
           platforms: linux/amd64,linux/arm64
           push: ${{ github.ref == 'refs/heads/main' || startsWith(github.ref, 'refs/tags/') }}
-          tags: |
-            ghcr.io/${{ github.repository }}${{ steps.vars.outputs.suffix }}:${{ steps.vars.outputs.tag }}
+          tags: ${{ steps.meta.outputs.tags }}
+          labels: ${{ steps.meta.outputs.labels }}
           cache-from: type=gha
           cache-to: type=gha,mode=max