Make port configurable

README.md

@@ -112,7 +112,9 @@ make run
 
 ## Health check
 
-The launcher exposes a health check endpoint at `/healthz` on port `5681` for liveness checks.
+The launcher exposes a health check endpoint at `/healthz` on port `5681` for liveness checks. To override the launcher health check port, set the `N8N_LAUNCHER_HEALTCHECK_PORT` env var. 
+
+If overriding the default health check port, be mindful of port conflicts - the n8n main instance uses `5678` by default for its HTTP server and `5679` for its WS server, and the runner uses `5680` by default for its WS server. 
 
 ## Release
 

cmd/launcher/main.go

@@ -2,7 +2,7 @@ package main
 
 import (
 	"flag"
-	"fmt"
+	"net"
 	"os"
 
 	"task-runner-launcher/internal/commands"
@@ -24,9 +24,13 @@ func main() {
 
 	srv := http.NewHealthCheckServer()
 	go func() {
+		logs.Logger.Printf("Starting health check server at port %d", http.GetPort())
+
 		if err := srv.ListenAndServe(); err != nil {
-			fmt.Printf("Health check server failed to start: %s", err)
-			os.Exit(1)
+			if opErr, ok := err.(*net.OpError); ok && opErr.Op == "listen" {
+				logs.Logger.Fatalf("Health check server failed to start: Port %d is already in use", http.GetPort())
+			}
+			logs.Logger.Fatalf("Health check server failed to start: %s", err)
 		}
 	}()
 

internal/http/healthcheck_server.go

@@ -4,12 +4,15 @@ import (
 	"encoding/json"
 	"fmt"
 	"net/http"
+	"os"
+	"strconv"
 	"task-runner-launcher/internal/logs"
 	"time"
 )
 
 const (
 	defaultPort     = 5681
+	portEnvVar      = "N8N_LAUNCHER_HEALTCHECK_PORT"
 	healthCheckPath = "/healthz"
 	readTimeout     = 5 * time.Second
 	writeTimeout    = 5 * time.Second
@@ -20,7 +23,7 @@ func NewHealthCheckServer() *http.Server {
 	mux.HandleFunc(healthCheckPath, handleHealthCheck)
 
 	return &http.Server{
-		Addr:         fmt.Sprintf(":%d", defaultPort),
+		Addr:         fmt.Sprintf(":%d", GetPort()),
 		Handler:      mux,
 		ReadTimeout:  readTimeout,
 		WriteTimeout: writeTimeout,
@@ -45,3 +48,14 @@ func handleHealthCheck(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 }
+
+func GetPort() int {
+	if customPortStr := os.Getenv(portEnvVar); customPortStr != "" {
+		if customPort, err := strconv.Atoi(customPortStr); err == nil && customPort > 0 && customPort < 65536 {
+			return customPort
+		}
+		logs.Logger.Printf("Invalid port in %s, falling back to default port %d", portEnvVar, defaultPort)
+	}
+
+	return defaultPort
+}