Add production Docker deployment

Amp-Thread-ID: https://ampcode.com/threads/T-01a02485-5574-707c-bff4-5668d83bee8a
Co-authored-by: Heaust Azure <heaust.azure@gmail.com>

server/app.go

@@ -53,6 +53,7 @@ func newApplication(store *playgroundStore, packages map[string]memoryAsset, mon
 
 func (app *application) routes() http.Handler {
 	mux := http.NewServeMux()
+	mux.HandleFunc("/healthz", app.health)
 	mux.HandleFunc("/pkg/", app.servePackage)
 	mux.HandleFunc("/api/playgrounds", app.savePlayground)
 	mux.HandleFunc("/api/playgrounds/", app.getPlayground)
@@ -66,6 +67,15 @@ func (app *application) routes() http.Handler {
 	return app.headers(mux)
 }
 
+func (app *application) health(response http.ResponseWriter, request *http.Request) {
+	if request.Method != http.MethodGet && request.Method != http.MethodHead {
+		response.Header().Set("Allow", "GET, HEAD")
+		http.Error(response, "method not allowed", http.StatusMethodNotAllowed)
+		return
+	}
+	response.WriteHeader(http.StatusNoContent)
+}
+
 func (app *application) headers(next http.Handler) http.Handler {
 	return http.HandlerFunc(func(response http.ResponseWriter, request *http.Request) {
 		response.Header().Set("Cross-Origin-Opener-Policy", "same-origin")