Add json output

Signed-off-by: CrazyMax <crazy-max@users.noreply.github.com>

.github/workflows/ci.yml

@@ -165,6 +165,30 @@ jobs:
             org.opencontainers.image.description=Another description
             org.opencontainers.image.vendor=MyCompany
 
+  json:
+    runs-on: ubuntu-latest
+    steps:
+      -
+        name: Checkout
+        uses: actions/checkout@v2
+      -
+        name: Docker meta
+        id: meta
+        uses: ./
+        with:
+          images: |
+            ${{ env.DOCKER_IMAGE }}
+            ghcr.io/name/app
+          labels: |
+            maintainer=CrazyMax
+      -
+        name: JSON output
+        run: |
+          echo "maintainer=${{ fromJSON(steps.meta.outputs.json).labels['maintainer'] }}"
+          echo "version=${{ fromJSON(steps.meta.outputs.json).labels['org.opencontainers.image.version'] }}"
+          echo "revision=${{ fromJSON(steps.meta.outputs.json).labels['org.opencontainers.image.revision'] }}"
+          echo "created=${{ fromJSON(steps.meta.outputs.json).labels['org.opencontainers.image.created'] }}"
+
   docker-push:
     runs-on: ubuntu-latest
     services: