An attempt to divorce the start of the WS and UI

The intent is to be able to run on a remote system and tunnel
over ssh to the host and port so that it can start up and run
without the need for X or a GNU/KDE desktop

Change-Id: I6ad5843dc7c2963d379eaa4c3b842feacb016fff

docs/source/developers.md

@@ -21,6 +21,25 @@ Run the airshipui binary
 
     ./bin/airshipui
 
+# Running on a separate client & server
+For development purposes it could be advantageous to split the webservice and the UI across 2 machines.
+
+## To start the webservice on a remote system without starting the ui
+
+    bin/airshipui --headless
+
+This will require you to tunnel the connection to the remote machine:
+
+    ssh -L 8080:localhost:8080 <id>@<remote_host>
+
+## To start the UI to attach to a remote machine
+
+    bin/airshipui --remote
+
+## Running the webservice on a remote machine with plugins
+The plugins can run on the remote system but you will need to add additional SSH tunnels to the machine in order for it to work.
+The plugins can also run locally but the remote server will still need the definition on the remote system to notify the UI that the plugins are available.
+
 # Authentication
 ## Pluggable authentication methods
 The AirshipUI is not designed to create authentication credentials but to have them supplied to it either by a configuration or by an external entity.  The expectation is that there will be an external URL that will handle authentication for the system which may need to be modified or created.  The endpoint will need to be able to forward a [bearer token](https://oauth.net/2/bearer-tokens/), [basic auth](https://en.wikipedia.org/wiki/Basic_access_authentication) or cookie data to the Airship UI backend service.

internal/commands/root.go

@@ -38,21 +38,19 @@ var rootCmd = &cobra.Command{
 	Version: Version(),
 }
 
+var headless bool
+var remote bool
+
 func init() {
 	// Add a 'version' command, in addition to the '--version' option that is auto created
 	rootCmd.AddCommand(newVersionCmd())
+
+	// add the remote & headless options in case people want to run a split setup
+	rootCmd.Flags().BoolVar(&headless, "headless", false, "start the system in headless webserver only, no ui.")
+	rootCmd.Flags().BoolVar(&remote, "remote", false, "start the system in remote ui only, no webserver.")
 }
 
 func launch(cmd *cobra.Command, args []string) {
-	// only process args if there are any
-	// TODO: what flags do we care about and what shall we do with them?
-	if cmd.Flags().NFlag() > 0 {
-		log.Printf("Executing AirshipUI with the following args: %v\n", args)
-	}
-
-	// start the webservice
-	go webservice.WebServer()
-
 	sigs := make(chan os.Signal)
 	signal.Notify(sigs, syscall.SIGINT, syscall.SIGTERM)
 
@@ -86,18 +84,56 @@ func launch(cmd *cobra.Command, args []string) {
 		)
 	}
 
-	// start the electron app
-	err := electron.RunElectron()
+	// just a little ditty to see if we should open the ui or the webservice or both
+	switch handleStartType() {
+	case "headless":
+		// start webservice and listen for the the ctl + c to exit
+		c := make(chan os.Signal)
+		signal.Notify(c, os.Interrupt, syscall.SIGTERM)
+		go func() {
+			<-c
+			log.Println("Exiting the webservice")
+			os.Exit(0)
+		}()
+		webservice.WebServer()
+	case "remote":
+		// start the electron app
+		startElectron()
+	default:
+		// start webservice and electron
+		go webservice.WebServer()
+		startElectron()
+	}
 
 	// cancel running plugins and wait for shut down
 	cancel()
 	waitgrp.Wait()
+}
 
+func startElectron() {
+	err := electron.RunElectron()
 	if err != nil {
 		log.Printf("Exit %s", err)
 	}
 }
 
+// TODO: determine if cobra can make flags exclusive without the extra logic
+func handleStartType() string {
+	st := "default"
+	if remote && headless {
+		log.Fatalf("Cannot set both --remote and --headless flags")
+	}
+
+	if remote {
+		st = "remote"
+	} else if headless {
+		st = "headless"
+	}
+
+	return st
+}
+
+// Execute is called from the main program and kicks this whole shindig off
 func Execute() {
 	if err := rootCmd.Execute(); err != nil {
 		log.Println(err)