add a github action to publish a docker container for ws

.github/workflows/docker.yml

@@ -0,0 +1,66 @@
+name: docker
+
+# When its time to do a release do a build for amd64
+# and push all of them to Docker Hub.
+# Only trigger on semver shaped tags.
+on:
+  push:
+    tags:
+      - "v*.*.*"
+
+jobs:
+  login:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v2
+
+      - name: Prepare
+        id: prep
+        run: |
+          DOCKER_IMAGE=machinezone/ws
+          VERSION=edge
+          if [[ $GITHUB_REF == refs/tags/* ]]; then
+            VERSION=${GITHUB_REF#refs/tags/v}
+          fi
+          if [ "${{ github.event_name }}" = "schedule" ]; then
+            VERSION=nightly
+          fi
+          TAGS="${DOCKER_IMAGE}:${VERSION}"
+          if [[ $VERSION =~ ^[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}$ ]]; then
+            TAGS="$TAGS,${DOCKER_IMAGE}:latest"
+          fi
+          echo ::set-output name=tags::${TAGS}
+
+      - name: Set up Docker Buildx
+        id: buildx
+        uses: docker/setup-buildx-action@master
+
+      - name: Cache Docker layers
+        uses: actions/cache@v2
+        with:
+          path: /tmp/.buildx-cache
+          key: ${{ runner.os }}-buildx-${{ github.sha }}
+          restore-keys: |
+            ${{ runner.os }}-buildx-
+
+      - name: Login to GitHub Package Registry
+        uses: docker/login-action@v1
+        with:
+          registry: ghcr.io
+          username: ${{ github.repository_owner }}
+          password: ${{ secrets.GHCR_TOKEN }}
+
+      - name: Build and push
+        id: docker_build
+        uses: docker/build-push-action@v2-build-push
+        with:
+          builder: ${{ steps.buildx.outputs.name }}
+          context: .
+          file: ./Dockerfile
+          target: prod
+          platforms: linux/amd64
+          push: ${{ github.event_name != 'pull_request' }}
+          tags: ${{ steps.prep.outputs.tags }}
+          cache-from: type=local,src=/tmp/.buildx-cache
+          cache-to: type=local,dest=/tmp/.buildx-cache