Updating build flags and docker build instructions in readme.

Dockerfile

@@ -5,6 +5,9 @@ COPY go.mod go.sum ./
 RUN go mod download
 COPY . .
 RUN go generate -tags prod ./...
+ARG GIT_COMMIT
+ARG RELEASE_CODE
+ARG BUILD_TIME
 RUN CGO_ENABLED=0 GOOS=linux GOARCH=amd64 go install -ldflags "-w -s -extldflags '-static' -X main.GitCommit=$GIT_COMMIT -X main.ReleaseCode=$RELEASE_CODE -X 'main.BuildTime=$BUILD_TIME'" github.com/ngerakines/tavern/...
 
 FROM alpine:3.11 as tavern

README.md

@@ -30,6 +30,13 @@ The build and release process involves code generation in a few ways that aren't
 
 The `-tags prod` argument can be used to indicate prod vs non-prod sources. When the `prod` flag **is not** present, asset packages will load content from disk, but will still contain file path references. In other words, whenever you create or delete files including templates, migrations, or translations, you must run `go generate ./...`.
 
+## Docker Builds
+
+    $ export TAVERN_RELEASE_CODE=$(git describe --always)
+    $ export TAVERN_GIT_COMMIT=$(git log --format="%H" -n 1)
+    $ export TAVERN_BUILD_TIME=$(date --rfc-3339=seconds)
+    $ docker build --build-arg=GIT_COMMIT=$TAVERN_GIT_COMMIT --build-arg=RELEASE_CODE=$TAVERN_RELEASE_CODE --build-arg=BUILD_TIME="$TAVERN_BUILD_TIME" -t ngerakines/tavern:latest  --target=tavern .
+
 # License
 
 MIT License

main.go

@@ -25,7 +25,7 @@ var GitCommit string
 var BuildTime string
 
 func main() {
-	compiledAt, err := time.Parse(time.RFC822Z, BuildTime)
+	compiledAt, err := time.Parse(time.RFC3339, BuildTime)
 	if err != nil {
 		compiledAt = time.Now()
 	}

web/command.go

@@ -244,10 +244,23 @@ func serverCommandAction(cliCtx *cli.Context) error {
 	assetQueue := common.NewStringQueue()
 
 	registry := prometheus.NewRegistry()
+
 	if err = registry.Register(prometheus.NewGoCollector()); err != nil {
 		return err
 	}
 	fact := promauto.With(registry)
+
+	{
+		tavernInfoG := fact.NewGauge(prometheus.GaugeOpts{
+			Namespace:   "tavern",
+			Subsystem:   "web",
+			Name:        "info",
+			Help:        "",
+			ConstLabels: map[string]string{"buildtime": g.BuildTime, "version": g.Version(), "ua": g.UserAgent()},
+		})
+		tavernInfoG.Set(1)
+	}
+
 	httpClient := common.InstrumentedDefaultHTTPClient(fact, "web", "client")
 
 	var svgConv SVGConverter