Add CORS headers so bus can be accessed cross-origin

cmd/msgbusd/main.go

@@ -83,6 +83,14 @@ func parseArgs() error {
 	return nil
 }
 
+func corsMiddleware(next http.Handler) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Set("Access-Control-Allow-Origin", "*")
+		w.Header().Set("Access-Control-Allow-Headers", "*")
+		next.ServeHTTP(w, r)
+	})
+}
+
 func main() {
 	parseArgs()
 
@@ -109,7 +117,7 @@ func main() {
 	}
 	mb := msgbus.New(&opts)
 
-	http.Handle("/", mb)
+	http.Handle("/", corsMiddleware(mb))
 	http.Handle("/metrics", mb.Metrics().Handler())
 	log.Infof("msgbusd %s listening on %s", msgbus.FullVersion(), bind)
 	log.Fatal(http.ListenAndServe(bind, nil))

go.mod

@@ -3,7 +3,7 @@ module git.mills.io/prologic/msgbus
 go 1.17
 
 require (
-	github.com/gorilla/websocket v1.5.0 // indirect
+	github.com/gorilla/websocket v1.5.0
 	github.com/jpillora/backoff v1.0.0
 	github.com/mitchellh/go-homedir v1.1.0
 	github.com/mmcloughlin/professor v0.0.0-20170922221822-6b97112ab8b3