Make api URL dynamic in web app

pkg/api/api.go

@@ -25,8 +25,7 @@ func New(token string) *API {
 
 func (api *API) EnableCors(fn http.HandlerFunc) http.HandlerFunc {
 	return func(w http.ResponseWriter, r *http.Request) {
-		w.Header().Add("Access-Control-Allow-Origin", "http://localhost:8001") // todo: configurable port
-		w.Header().Add("Access-Control-Allow-Credentials", "true")
+		w.Header().Add("Access-Control-Allow-Origin", "*")
 		w.Header().Add("Access-Control-Allow-Headers", "Content-Type, Content-Length, Accept-Encoding, X-CSRF-Token, Authorization, accept, origin, Cache-Control, X-Requested-With")
 		w.Header().Add("Access-Control-Allow-Methods", "POST, GET, OPTIONS, PUT, DELETE")
 

pkg/dashboard/dashboard.go

@@ -1,36 +1,82 @@
 package dashboard
 
 import (
+	"fmt"
+	"html/template"
 	"net/http"
+	"strings"
 
 	log "github.com/sirupsen/logrus"
 )
 
 // Dashboard is the http server responsible for serving the static Dashboard files
 type Dashboard struct {
+	port       string
+	rootDir    string
+	apiPort    string
+	apiScheme  string
+	apiVersion string
 }
 
 // New is a factory function creating a new Dashboard instance
 func New() *Dashboard {
-	return &Dashboard{}
+	const webRootDir = "./web/static" // Todo: needs to work in containerized environment
+	const webPort = "8001"            // Todo: make configurable?
+	const apiPort = "8080"            // Todo: make configurable?
+
+	return &Dashboard{
+		apiPort:    apiPort,
+		apiScheme:  "http",
+		apiVersion: "v1",
+		rootDir:    webRootDir,
+		port:       webPort,
+	}
 }
 
 // Start the Dashboard and serve over HTTP
-func (dashboard *Dashboard) Start() error {
+func (d *Dashboard) Start() error {
 	go func() {
-		runHTTPServer()
+		d.runHTTPServer()
 	}()
 	return nil
 }
 
-func runHTTPServer() {
+func (d *Dashboard) templatedHttpHandler(h http.Handler) http.HandlerFunc {
+	const apiUrlTemplate = "%s://%s:%s/%s/"
+	indexTemplate, err := template.ParseFiles(d.rootDir + "/index.html")
+	if err != nil {
+		log.Error("Error when parsing index template")
+		log.Error(err)
+		return nil
+	}
+
+	return func(w http.ResponseWriter, r *http.Request) {
+		if r.URL.Path == "/" {
+			hostName := strings.Split(r.Host, ":")[0]
+			apiUrl := fmt.Sprintf(apiUrlTemplate, d.apiScheme, hostName, d.apiPort, d.apiVersion)
+			err = indexTemplate.Execute(w, struct{ ApiUrl string }{
+				ApiUrl: apiUrl,
+			})
+			if err != nil {
+				log.Error("Error when executing index template")
+				log.Error(err)
+				w.WriteHeader(http.StatusInternalServerError)
+				return
+			}
+		} else {
+			h.ServeHTTP(w, r)
+		}
+	}
+}
+
+func (d *Dashboard) getHandler() http.Handler {
+	return d.templatedHttpHandler(http.FileServer(http.Dir(d.rootDir)))
+}
+
+func (d *Dashboard) runHTTPServer() {
 	serveMux := http.NewServeMux()
-	serveMux.Handle("/", getHandler())
+	serveMux.Handle("/", d.getHandler())
 
 	log.Debug("Starting http dashboard server")
-	log.Fatal(http.ListenAndServe(":8001", serveMux))
-}
-
-func getHandler() http.Handler {
-	return http.FileServer(http.Dir("./web/static"))
+	log.Fatal(http.ListenAndServe(":"+d.port, serveMux))
 }