Release a light image tag

Omit all plugins except the shell plugin that will be included in the main binary.

.github/workflows/release.yml

@@ -40,9 +40,7 @@ jobs:
 
       - name: set up buildx
         id: buildx
-        uses: crazy-max/ghaction-docker-buildx@v1
-        with:
-          version: latest
+        uses: docker/setup-buildx-action@v1
 
       - name: login to dockerhub
         run: echo "${{ secrets.DOCKER_PASSWORD }}" | docker login -u ${{ secrets.DOCKER_USERNAME }} --password-stdin
@@ -60,3 +58,15 @@ jobs:
             -t ${DOCKER_REPO:-dkron/dkron}:latest \
             -f Dockerfile.hub \
             .
+      - name: build (and publish) light image
+        env:
+          # fork friendly ^^
+          DOCKER_REPO: ${{ secrets.DOCKER_REPO }}
+        run: |
+          docker buildx build \
+            --platform linux/amd64,linux/arm64,linux/arm/v7 \
+            --build-arg VERSION=${{ steps.prepare.outputs.tag_name }} \
+            --push \
+            -t ${DOCKER_REPO:-dkron/dkron}:${{ steps.prepare.outputs.tag_name }}-light \
+            -f Dockerfile.light.hub \
+            .

Dockerfile.light.hub

@@ -0,0 +1,21 @@
+# syntax=docker/dockerfile:1.2
+FROM alpine:3.12
+LABEL maintainer="Victor Castell <victor@victorcastell.com>"
+ARG TARGETPLATFORM
+
+RUN set -x \
+	&& buildDeps='bash ca-certificates openssl tzdata' \
+	&& apk add --update $buildDeps \
+	&& rm -rf /var/cache/apk/* \
+	&& mkdir -p /opt/local/dkron
+
+EXPOSE 8080 8946
+
+ENV SHELL /bin/bash
+WORKDIR /opt/local/dkron
+
+RUN --mount=target=/build cp /build/dist/dkron_$(echo ${TARGETPLATFORM} | tr '/' '_')/dkron .
+
+ENTRYPOINT ["/opt/local/dkron/dkron"]
+
+CMD ["--help"]