Allow running multiple clients on the same system

Author: mjarkk

main.go

@@ -9,7 +9,6 @@ import (
 	"os"
 	"os/exec"
 	"syscall"
-	"time"
 )
 
 // Env contains the structure of the .env file
@@ -90,7 +89,7 @@ func main() {
 	}
 
 	api := NewAPI()
-	go startWebserver(env, api)
+	useAddress := startWebserver(env, api)
 
 	credentials := []SetCredentialsArg{env.PrimaryServer.toCredArg(true)}
 	for _, server := range env.AlternativeServers {
@@ -122,7 +121,7 @@ func main() {
 	}
 
 	scraper := exec.Command(os.Args[1], os.Args[2:]...)
-	scraper.Env = append(os.Environ(), "SCRAPER_ADDRESS=http://localhost:4400")
+	scraper.Env = append(os.Environ(), "SCRAPER_ADDRESS="+useAddress)
 
 	// Piple output of scraper to stdout
 	scraper.Stdin = os.Stdin
@@ -168,14 +167,4 @@ func testServerConnections(api *API) {
 			log.Fatal("provided key does not have scraper role (nr 1)")
 		}
 	}
-
-	referenceNrs := []string{}
-	err := api.connections[api.primaryConnection].Get("/api/v1/scraper/scannedReferenceNrs/since/days/30", &referenceNrs)
-	if err != nil {
-		log.Fatal(err)
-	}
-
-	for _, nr := range referenceNrs {
-		api.SetCacheEntry(nr, time.Hour*72) // 3 days
-	}
 }

webserver.go

@@ -2,13 +2,16 @@ package main
 
 import (
 	"encoding/json"
+	"fmt"
 	"log"
+	"net"
+	"strings"
 	"time"
 
 	"github.com/valyala/fasthttp"
 )
 
-func startWebserver(env Env, api *API) {
+func startWebserver(env Env, api *API) string {
 	loginUsers, err := json.Marshal(env.LoginUsers)
 	if err != nil {
 		log.Fatal(err)
@@ -110,9 +113,34 @@ func startWebserver(env Env, api *API) {
 	}
 
 	s := &fasthttp.Server{Handler: requestHandler}
-	err = s.ListenAndServe("127.0.0.1:4400")
-	if err != nil {
-		log.Fatal("Error in ListenAndServe: " + err.Error())
+
+	portAttempt := 4_000
+	for {
+		portAttempt++
+		if portAttempt > 6_000 {
+			// Give up
+			log.Fatal("Could not find a free port to start the webserver")
+		}
+
+		address := fmt.Sprintf("127.0.0.1:%d", portAttempt)
+
+		l, err := net.Listen("tcp4", address)
+		if err != nil {
+			if strings.Contains(err.Error(), "address already in use") {
+				// Retry with a diffrent port
+				continue
+			}
+			log.Fatal("Error in Listen: " + err.Error())
+		}
+
+		go func() {
+			err = s.Serve(l)
+			if err != nil {
+				log.Fatal("Error in Serve: " + err.Error())
+			}
+		}()
+
+		return "http://" + address
 	}
 }