Fix Dockerfile image and add /health endpoint

Dockerfile

@@ -1,16 +1,49 @@
 # Build
-FROM prologic/go-builder:latest AS build
+FROM golang:alpine AS build
+
+RUN apk add --no-cache -U build-base git make
+
+RUN mkdir -p /src
+
+WORKDIR /src
+
+# Copy Makefile
+COPY Makefile ./
+
+# Copy go.mod and go.sum and install and cache dependencies
+COPY go.mod .
+COPY go.sum .
+
+# Install deps
+RUN go mod download
+
+# Copy sources
+COPY *.go ./
+
+# Version/Commit (there there is no .git in Docker build context)
+# NOTE: This is fairly low down in the Dockerfile instructions so
+#       we don't break the Docker build cache just be changing
+#       unrelated files that actually haven't changed but caused the
+#       COMMIT value to change.
+ARG VERSION="0.0.0"
+ARG COMMIT="HEAD"
+
+# Build server binary
+RUN make VERSION=$VERSION COMMIT=$COMMIT
 
 # Runtime
 FROM alpine:latest
 
-RUN apk --no-cache -U add ca-certificates
+RUN apk --no-cache -U add curl ca-certificates tzdata
 
 WORKDIR /
 VOLUME /feeds
 
-COPY .dockerfiles/config.yaml /config.yaml
+# force cgo resolver
+ENV GODEBUG=netdns=cgo
+
 COPY --from=build /src/rss2twtxt /rss2twtxt
 
+HEALTHCHECK CMD curl -qsfSL http://127.0.0.1:8000/health || exit 1
 ENTRYPOINT ["/rss2twtxt"]
 CMD [""]

Makefile

@@ -13,8 +13,8 @@ build:
 	@go build \
 		-tags "netgo static_build" -installsuffix netgo \
 		-ldflags "-w \
-		-X $(shell go list).Version=$(VERSION) \
-		-X $(shell go list).Commit=$(COMMIT)" \
+		-X main.Version=$(VERSION) \
+		-X main.Commit=$(COMMIT)" \
 		.
 
 install: build

app.go

@@ -39,6 +39,7 @@ func (app *App) initRoutes() *mux.Router {
 	router := mux.NewRouter().StrictSlash(true)
 
 	router.HandleFunc("/", app.IndexHandler).Methods(http.MethodGet, http.MethodHead, http.MethodPost)
+	router.HandleFunc("/health", app.HealthHandler).Methods(http.MethodGet, http.MethodHead)
 	router.HandleFunc("/feeds", app.FeedsHandler).Methods(http.MethodGet, http.MethodHead)
 	router.HandleFunc("/we-are-feeds.txt", app.WeAreFeedsHandler).Methods(http.MethodGet, http.MethodHead)
 	router.HandleFunc("/{name}/twtxt.txt", app.FeedHandler).Methods(http.MethodGet, http.MethodHead)

handlers.go

@@ -43,6 +43,11 @@ func renderMessage(w http.ResponseWriter, status int, title, message string) err
 	return nil
 }
 
+func (app *App) HealthHandler(w http.ResponseWriter, r *http.Request) {
+	defer r.Body.Close()
+	return
+}
+
 func (app *App) IndexHandler(w http.ResponseWriter, r *http.Request) {
 	if r.Method == http.MethodHead || r.Method == http.MethodGet {
 		w.Header().Set("Content-Type", "text/html")

version.go

@@ -8,14 +8,11 @@ var (
 	// Version release version
 	Version = "0.0.1"
 
-	// Build will be overwritten automatically by the build system
-	Build = "dev"
-
-	// GitCommit will be overwritten automatically by the build system
-	GitCommit = "HEAD"
+	// Commit will be overwritten automatically by the build system
+	Commit = "HEAD"
 )
 
 // FullVersion returns the full version, build and commit hash
 func FullVersion() string {
-	return fmt.Sprintf("%s-%s@%s", Version, Build, GitCommit)
+	return fmt.Sprintf("%s@%s", Version, Commit)
 }