feat: add github action to build docker images and push to ghcr.io on release (#1614)

.github/workflows/main.yml

@@ -0,0 +1,45 @@
+name: Publish Docker image
+on:
+  release:
+    types: [published]
+jobs:
+  push_to_registry:
+    name: Push Docker image to GitHub Packages
+    runs-on: ubuntu-latest
+    permissions:
+      packages: write
+      contents: read
+    steps:
+      - name: Check out the repo
+        uses: actions/checkout@v2
+      - name: Login to GitHub Container Registry
+        uses: docker/login-action@v1
+        with:
+          registry: ghcr.io
+          username: ${{ github.repository_owner }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+      - name: Prepare
+        id: prep
+        run: |
+          DOCKER_IMAGE=ghcr.io/redocly/redoc/cli
+          VERSION=edge
+          if [[ $GITHUB_REF == refs/tags/* ]]; then
+            VERSION=${GITHUB_REF#refs/tags/}
+          elif [[ $GITHUB_REF == refs/heads/* ]]; then
+            VERSION=$(echo ${GITHUB_REF#refs/heads/} | sed -r 's#/+#-#g')
+          elif [[ $GITHUB_REF == refs/pull/* ]]; then
+            VERSION=pr-${{ github.event.number }}
+          fi
+          TAGS="${DOCKER_IMAGE}:${VERSION}"
+          if [ "${{ github.event_name }}" = "push" ]; then
+            TAGS="$TAGS,${DOCKER_IMAGE}:sha-${GITHUB_SHA::8}"
+          fi
+          echo ::set-output name=version::${VERSION}
+          echo ::set-output name=tags::${TAGS}
+          echo ::set-output name=created::$(date -u +'%Y-%m-%dT%H:%M:%SZ')
+      - name: Push to GitHub Packages
+        uses: docker/build-push-action@v2
+        with:
+          context: ./cli
+          push: ${{ github.event_name != 'pull_request' }}
+          tags: ${{ steps.prep.outputs.tags }}