Publish to DockerHub when a new tag is created

The publish to DockerHub appears to have been broken for a while now.
This attempts to address the issue by adding a new GitHub action to
handle pushing to DockerHub if the current ref is a tag.

This did involve some changes to the Dockerfile. I've tested the result
and updated the `docker_test` target accordingly.

.github/workflows/dockerhub.yaml

@@ -0,0 +1,25 @@
+name: Deploy Docker Image
+
+on:
+  create: ~
+
+jobs:
+  deploy:
+    if: ${{ startsWith(github.ref, 'refs/tags/v') }}
+    runs-on: ubuntu-latest
+    steps:
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v1
+
+      - name: Login to DockerHub
+        uses: docker/login-action@v1
+        with:
+          username: ${{ secrets.DOCKER_USERNAME }}
+          password: ${{ secrets.DOCKER_TOKEN }}
+
+      - name: Build and push
+        id: docker_build
+        uses: docker/build-push-action@v2
+        with:
+          push: true
+          tags: pseudomuto/protoc-gen-doc:${{ github.sha }}, pseudomuto/protoc-gen-doc:latest

Dockerfile

@@ -1,4 +1,11 @@
-FROM debian:jessie-slim
+FROM golang:1.17-alpine AS builder
+WORKDIR /build
+COPY go.mod go.sum ./
+RUN go mod download
+COPY . ./
+RUN CGO_ENABLED=0 go build -ldflags="-s -w" -o protoc-gen-doc ./cmd/protoc-gen-doc
+
+FROM debian:jessie-slim AS final
 LABEL maintainer="pseudomuto <[email protected]>" protoc_version="3.6.1"
 
 WORKDIR /
@@ -12,8 +19,8 @@ RUN apt-get -q -y update && \
   apt-get autoremove && \
   rm -rf /var/lib/apt/lists/*
 
-ADD dist/protoc-gen-doc /usr/local/bin/
-ADD script/entrypoint.sh ./
+COPY --from=builder /build/protoc-gen-doc /usr/local/bin
+COPY script/entrypoint.sh ./
 
 VOLUME ["/out", "/protos"]
 

Makefile

@@ -17,7 +17,7 @@ DOCKER_CMD=docker run --rm \
 	-v $(PWD)/thirdparty/github.com/mwitkow:/usr/local/include/github.com/mwitkow:ro \
 	-v $(PWD)/thirdparty/github.com/envoyproxy:/usr/local/include/github.com/envoyproxy:ro \
 	-v $(PWD)/tmp/googleapis/google/api:/usr/local/include/google/api:ro \
-	pseudomuto/protoc-gen-doc
+	pseudomuto/protoc-gen-doc:local
 
 VERSION = $(shell cat version.go | sed -n 's/.*const VERSION = "\(.*\)"/\1/p')
 
@@ -49,11 +49,9 @@ build: resources.go
 dist:
 	@script/dist.sh
 
-docker:
-	@script/push_to_docker.sh
-
-docker_test: build tmp/googleapis docker
+docker_test: tmp/googleapis
 	@rm -f examples/doc/*
+	@docker build -t pseudomuto/protoc-gen-doc:local .
 	@$(DOCKER_CMD) --doc_opt=docbook,example.docbook:Ignore*
 	@$(DOCKER_CMD) --doc_opt=html,example.html:Ignore*
 	@$(DOCKER_CMD) --doc_opt=json,example.json:Ignore*