Start working on web server (#2)

* Start working on web server

* Some restructure

* Serving static works

* Fix linter complaint

* Enable local dev

* Static files served fine

* Tidy

pkg/dashboard/server.go

@@ -0,0 +1,54 @@
+package dashboard
+
+import (
+	"context"
+	"github.com/gin-gonic/gin"
+	log "github.com/sirupsen/logrus"
+	"net/http"
+	"os"
+	"strings"
+)
+
+func StartServer() (string, ControlChan) {
+	data := DataLayer{}
+	data.CheckConnectivity()
+
+	address := os.Getenv("HD_BIND")
+	if os.Getenv("HD_PORT") == "" {
+		address += ":8080" // TODO: better default port to clash less?
+	} else {
+		address += ":" + os.Getenv("HD_PORT")
+	}
+
+	abort := make(ControlChan)
+	api := newRouter(abort, data)
+	done := startBackgroundServer(address, api, abort)
+
+	if strings.HasPrefix(address, ":") {
+		address = "localhost" + address
+	}
+	return "http://" + address, done
+}
+
+func startBackgroundServer(addr string, routes *gin.Engine, abort ControlChan) ControlChan {
+	done := make(ControlChan)
+	server := &http.Server{Addr: addr, Handler: routes}
+
+	go func() {
+		err := server.ListenAndServe()
+		if err != nil && err != http.ErrServerClosed {
+			panic(err) // TODO: in case of "port busy", check that it's another instance of us and just open browser
+		}
+		done <- struct{}{}
+	}()
+
+	go func() {
+		<-abort
+		err := server.Shutdown(context.Background())
+		if err != nil {
+			log.Warnf("Had problems shutting down the server: %s", err)
+		}
+	}()
+
+	return done
+}