From a71cd1c6ae26110abf791152bbeef184cbed681c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Iv=C3=A1n=20Ovejero?= <ivov.src@gmail.com>
Date: Mon, 2 Dec 2024 12:22:43 +0100
Subject: [PATCH] refactor: Encapsulate health check server logic (#46)

---
 cmd/launcher/main.go                     | 15 +--------------
 internal/http/healthcheck_server.go      | 22 +++++++++++++++++++++-
 internal/http/healthcheck_server_test.go |  2 +-
 3 files changed, 23 insertions(+), 16 deletions(-)

diff --git a/cmd/launcher/main.go b/cmd/launcher/main.go
index ef2df7d..2d1eacb 100644
--- a/cmd/launcher/main.go
+++ b/cmd/launcher/main.go
@@ -3,7 +3,6 @@ package main
 import (
 	"flag"
 	"fmt"
-	"net"
 	"os"
 
 	"task-runner-launcher/internal/commands"
@@ -40,19 +39,7 @@ func main() {
 	errorreporting.Init(cfg.Sentry)
 	defer errorreporting.Close()
 
-	srv := http.NewHealthCheckServer(cfg.HealthCheckServerPort)
-	go func() {
-		if err := srv.ListenAndServe(); err != nil {
-			errMsg := "Health check server failed to start"
-			if opErr, ok := err.(*net.OpError); ok && opErr.Op == "listen" {
-				errMsg = fmt.Sprintf("%s: Port %s is already in use", errMsg, srv.Addr)
-			} else {
-				errMsg = fmt.Sprintf("%s: %s", errMsg, err)
-			}
-			logs.Error(errMsg)
-		}
-		logs.Infof("Started launcher's health check server at port %d", srv.Addr)
-	}()
+	http.InitHealthCheckServer(cfg.HealthCheckServerPort)
 
 	cmd := &commands.LaunchCommand{}
 
diff --git a/internal/http/healthcheck_server.go b/internal/http/healthcheck_server.go
index 6d9c52b..c07fa63 100644
--- a/internal/http/healthcheck_server.go
+++ b/internal/http/healthcheck_server.go
@@ -3,6 +3,7 @@ package http
 import (
 	"encoding/json"
 	"fmt"
+	"net"
 	"net/http"
 	"task-runner-launcher/internal/logs"
 	"time"
@@ -14,7 +15,26 @@ const (
 	writeTimeout    = 1 * time.Second
 )
 
-func NewHealthCheckServer(port string) *http.Server {
+// InitHealthCheckServer creates and starts the launcher's health check server
+// exposing `/healthz` at the given port, running in a goroutine.
+func InitHealthCheckServer(port string) {
+	srv := newHealthCheckServer(port)
+	go func() {
+		logs.Infof("Starting launcher's health check server at port %s", port)
+		if err := srv.ListenAndServe(); err != nil {
+			errMsg := "Health check server failed to start"
+			if opErr, ok := err.(*net.OpError); ok && opErr.Op == "listen" {
+				errMsg = fmt.Sprintf("%s: Port %s is already in use", errMsg, srv.Addr)
+			} else {
+				errMsg = fmt.Sprintf("%s: %s", errMsg, err)
+			}
+			logs.Error(errMsg)
+			return
+		}
+	}()
+}
+
+func newHealthCheckServer(port string) *http.Server {
 	mux := http.NewServeMux()
 	mux.HandleFunc(healthCheckPath, handleHealthCheck)
 
diff --git a/internal/http/healthcheck_server_test.go b/internal/http/healthcheck_server_test.go
index ad1281e..0304b9d 100644
--- a/internal/http/healthcheck_server_test.go
+++ b/internal/http/healthcheck_server_test.go
@@ -86,7 +86,7 @@ func (w *failingWriter) WriteHeader(statusCode int) {
 }
 
 func TestNewHealthCheckServer(t *testing.T) {
-	server := NewHealthCheckServer("5680")
+	server := newHealthCheckServer("5680")
 
 	require.NotNil(t, server, "server should not be nil")