🔥 Feature: add ability to print custom message on startup (#2491)

* feat: add a variadic parameter on OnListenHandler

* feat: accept a variadic ListenData in startupProcess parameters

* feat: add startupProcess variadic ListenData to function

* refactor: use runOnListenHooks instead of startupProcess for run onListenHooks

* refactor: remove variadic to make codes straightforward

* fix: add listen data to runOnListenHooks

* test: add listenData parameter to OnListen tests

* docs: update OnListen docs

* fix: remove unused codes

* docs: add tabs to onListen hook example

* docs: add if statement to docs example

* docs: replace fmt with log

* docs: fix return value of example

* docs: make 0.0.0.0 string a constant

* fix: change type of TLS from string to bool

* fix: return bool instead of a string

* docs: update example with new TLS type

* fix: change name tls to isTls to prevent shadowing tls variable

* style: make syntax of onListen example shorter

* refactor: remove unused no-lint comment

* refactor: change isTls to isTLS

* fix: add nolint for isTLS bool param

* Update listen.go

---------

Co-authored-by: M. Efe Çetin <efectn@protonmail.com>

app.go

@@ -1104,8 +1104,8 @@ func (app *App) startupProcess() *App {
 }
 
 // Run onListen hooks. If they return an error, panic.
-func (app *App) runOnListenHooks() {
-	if err := app.hooks.executeOnListenHooks(); err != nil {
+func (app *App) runOnListenHooks(listenData ListenData) {
+	if err := app.hooks.executeOnListenHooks(listenData); err != nil {
 		panic(err)
 	}
 }

docs/guide/hooks.md

@@ -24,9 +24,9 @@ type OnRouteHandler = func(Route) error
 type OnNameHandler = OnRouteHandler
 type OnGroupHandler = func(Group) error
 type OnGroupNameHandler = OnGroupHandler
-type OnListenHandler = func() error
+type OnListenHandler = func(ListenData) error
 type OnForkHandler = func(int) error
-type OnShutdownHandler = OnListenHandler
+type OnShutdownHandler = func() error
 type OnMountHandler = func(*App) error
 ```
 
@@ -127,6 +127,29 @@ OnListen is a hook to execute user functions on Listen, ListenTLS, Listener.
 func (app *App) OnListen(handler ...OnListenHandler)
 ```
 
+<Tabs>
+<TabItem value="onlisten-example" label="OnListen Example">
+
+```go
+app := fiber.New(fiber.Config{
+  DisableStartupMessage: true,
+})
+
+app.Hooks().OnListen(func(listenData fiber.ListenData) error {
+  if fiber.IsChild() {
+	  return nil
+  }
+  scheme := "http"
+  if data.TLS {
+    scheme = "https"
+  }
+  log.Println(scheme + "://" + listenData.Host + ":" + listenData.Port)
+  return nil
+})
+
+app.Listen(":5000")
+```
+
 ## OnFork
 
 OnFork is a hook to execute user functions on Fork.

hooks.go

@@ -10,8 +10,8 @@ type (
 	OnNameHandler      = OnRouteHandler
 	OnGroupHandler     = func(Group) error
 	OnGroupNameHandler = OnGroupHandler
-	OnListenHandler    = func() error
-	OnShutdownHandler  = OnListenHandler
+	OnListenHandler    = func(ListenData) error
+	OnShutdownHandler  = func() error
 	OnForkHandler      = func(int) error
 	OnMountHandler     = func(*App) error
 )
@@ -32,6 +32,13 @@ type Hooks struct {
 	onMount     []OnMountHandler
 }
 
+// ListenData is a struct to use it with OnListenHandler
+type ListenData struct {
+	Host string
+	Port string
+	TLS  bool
+}
+
 func newHooks(app *App) *Hooks {
 	return &Hooks{
 		app:         app,
@@ -174,9 +181,9 @@ func (h *Hooks) executeOnGroupNameHooks(group Group) error {
 	return nil
 }
 
-func (h *Hooks) executeOnListenHooks() error {
+func (h *Hooks) executeOnListenHooks(listenData ListenData) error {
 	for _, v := range h.onListen {
-		if err := v(); err != nil {
+		if err := v(listenData); err != nil {
 			return err
 		}
 	}

hooks_test.go

@@ -208,7 +208,7 @@ func Test_Hook_OnListen(t *testing.T) {
 	buf := bytebufferpool.Get()
 	defer bytebufferpool.Put(buf)
 
-	app.Hooks().OnListen(func() error {
+	app.Hooks().OnListen(func(listenData ListenData) error {
 		_, err := buf.WriteString("ready")
 		utils.AssertEqual(t, nil, err)
 
@@ -234,7 +234,7 @@ func Test_Hook_OnListenPrefork(t *testing.T) {
 	buf := bytebufferpool.Get()
 	defer bytebufferpool.Put(buf)
 
-	app.Hooks().OnListen(func() error {
+	app.Hooks().OnListen(func(listenData ListenData) error {
 		_, err := buf.WriteString("ready")
 		utils.AssertEqual(t, nil, err)
 

listen.go

@@ -25,13 +25,17 @@ import (
 	"github.com/mattn/go-runewidth"
 )
 
+const (
+	globalIpv4Addr = "0.0.0.0"
+)
+
 // Listener can be used to pass a custom listener.
 func (app *App) Listener(ln net.Listener) error {
 	// prepare the server for the start
 	app.startupProcess()
 
 	// run hooks
-	app.runOnListenHooks()
+	app.runOnListenHooks(app.prepareListenData(ln.Addr().String(), getTLSConfig(ln) != nil))
 
 	// Print startup message
 	if !app.config.DisableStartupMessage {
@@ -72,7 +76,7 @@ func (app *App) Listen(addr string) error {
 	app.startupProcess()
 
 	// run hooks
-	app.runOnListenHooks()
+	app.runOnListenHooks(app.prepareListenData(ln.Addr().String(), false))
 
 	// Print startup message
 	if !app.config.DisableStartupMessage {
@@ -137,7 +141,7 @@ func (app *App) ListenTLSWithCertificate(addr string, cert tls.Certificate) erro
 	app.startupProcess()
 
 	// run hooks
-	app.runOnListenHooks()
+	app.runOnListenHooks(app.prepareListenData(ln.Addr().String(), getTLSConfig(ln) != nil))
 
 	// Print startup message
 	if !app.config.DisableStartupMessage {
@@ -212,7 +216,7 @@ func (app *App) ListenMutualTLSWithCertificate(addr string, cert tls.Certificate
 	app.startupProcess()
 
 	// run hooks
-	app.runOnListenHooks()
+	app.runOnListenHooks(app.prepareListenData(ln.Addr().String(), getTLSConfig(ln) != nil))
 
 	// Print startup message
 	if !app.config.DisableStartupMessage {
@@ -231,8 +235,26 @@ func (app *App) ListenMutualTLSWithCertificate(addr string, cert tls.Certificate
 	return app.server.Serve(ln)
 }
 
+// prepareListenData create an slice of ListenData
+func (app *App) prepareListenData(addr string, isTLS bool) ListenData { //revive:disable-line:flag-parameter // Accepting a bool param named isTLS if fine here
+	host, port := parseAddr(addr)
+	if host == "" {
+		if app.config.Network == NetworkTCP6 {
+			host = "[::1]"
+		} else {
+			host = globalIpv4Addr
+		}
+	}
+
+	return ListenData{
+		Host: host,
+		Port: port,
+		TLS:  isTLS,
+	}
+}
+
 // startupMessage prepares the startup message with the handler number, port, address and other information
-func (app *App) startupMessage(addr string, tls bool, pids string) { //nolint: revive // Accepting a bool param is fine here
+func (app *App) startupMessage(addr string, isTLS bool, pids string) { //nolint: revive // Accepting a bool param named isTLS if fine here
 	// ignore child processes
 	if IsChild() {
 		return
@@ -294,12 +316,12 @@ func (app *App) startupMessage(addr string, tls bool, pids string) { //nolint: r
 		if app.config.Network == NetworkTCP6 {
 			host = "[::1]"
 		} else {
-			host = "0.0.0.0"
+			host = globalIpv4Addr
 		}
 	}
 
 	scheme := schemeHTTP
-	if tls {
+	if isTLS {
 		scheme = schemeHTTPS
 	}
 
@@ -320,7 +342,7 @@ func (app *App) startupMessage(addr string, tls bool, pids string) { //nolint: r
 	}
 	mainLogo += " │ " + centerValue("Fiber v"+Version, lineLen) + " │\n"
 
-	if host == "0.0.0.0" {
+	if host == globalIpv4Addr {
 		mainLogo += " │ " + center(fmt.Sprintf("%s://127.0.0.1:%s", scheme, port), lineLen) + " │\n" +
 			" │ " + center(fmt.Sprintf("(bound on host 0.0.0.0 and port %s)", port), lineLen) + " │\n"
 	} else {

prefork.go

@@ -128,7 +128,7 @@ func (app *App) prefork(network, addr string, tlsConfig *tls.Config) error {
 
 	// Run onListen hooks
 	// Hooks have to be run here as different as non-prefork mode due to they should run as child or master
-	app.runOnListenHooks()
+	app.runOnListenHooks(app.prepareListenData(addr, tlsConfig != nil))
 
 	// Print startup message
 	if !app.config.DisableStartupMessage {