✨ feat: Add Startup Probe to Healthcheck Middleware (#3069)

* added startup default probe endpoint

* added test case

* updated docs

* updated test order

* added test case

* fixed go fmt and md lint

* fixed go fmt and md lint

* updated doc as per coderabbitai suggestions

* changed healhtcheck route register to use default const instead of string for test cases

* updated whats new with healthcheck content

* updated whats new doc with coderabbitai sugg

* updated migration guide

docs/middleware/healthcheck.md

@@ -4,7 +4,7 @@ id: healthcheck
 
 # Health Check
 
-Liveness and readiness probes middleware for [Fiber](https://github.com/gofiber/fiber) that provides two endpoints for checking the liveness and readiness state of HTTP applications.
+Liveness, readiness and startup probes middleware for [Fiber](https://github.com/gofiber/fiber) that provides three endpoints for checking the liveness, readiness, and startup state of HTTP applications.
 
 ## Overview
 
@@ -16,6 +16,10 @@ Liveness and readiness probes middleware for [Fiber](https://github.com/gofiber/
   - **Default Endpoint**: `/readyz`
   - **Behavior**: By default returns `true` immediately when the server is operational.
 
+- **Startup Probe**: Checks if the application has completed its startup sequence and is ready to proceed with initialization and readiness checks.
+  - **Default Endpoint**: `/startupz`
+  - **Behavior**: By default returns `true` immediately when the server is operational.
+
 - **HTTP Status Codes**:
   - `200 OK`: Returned when the checker function evaluates to `true`.
   - `503 Service Unavailable`: Returned when the checker function evaluates to `false`.
@@ -44,6 +48,8 @@ After you initiate your [Fiber](https://github.com/gofiber/fiber) app, you can u
 app.Get(healthcheck.DefaultLivenessEndpoint, healthcheck.NewHealthChecker())
 // Provide a minimal config for readiness check
 app.Get(healthcheck.DefaultReadinessEndpoint, healthcheck.NewHealthChecker())
+// Provide a minimal config for startup check
+app.Get(healthcheck.DefaultStartupEndpoint, healthcheck.NewHealthChecker())
 // Provide a minimal config for check with custom endpoint
 app.Get("/live", healthcheck.NewHealthChecker())
 
@@ -59,6 +65,12 @@ app.Get(healthcheck.DefaultReadinessEndpoint, healthcheck.NewHealthChecker(healt
         return true
     },
 }))
+// And it works the same for startup, just change the route
+app.Get(healthcheck.DefaultStartupEndpoint, healthcheck.NewHealthChecker(healthcheck.Config{
+    Probe: func(c fiber.Ctx) bool {
+        return true
+    },
+}))
 // With a custom route and custom probe
 app.Get("/live", healthcheck.NewHealthChecker(healthcheck.Config{
     Probe: func(c fiber.Ctx) bool {
@@ -90,6 +102,10 @@ type Config struct {
     // Function used for checking the liveness of the application. Returns true if the application
     // is running and false if it is not. The liveness probe is typically used to indicate if 
     // the application is in a state where it can handle requests (e.g., the server is up and running).
+    // The readiness probe is typically used to indicate if the application is ready to start accepting traffic (e.g., all necessary components 
+    // are initialized and dependent services are available) and the startup probe typically used to 
+    // indicate if the application has completed its startup sequence and is ready to proceed with
+    // initialization and readiness checks
     //
     // Optional. Default: func(c fiber.Ctx) bool { return true }
     Probe HealthChecker

docs/whats_new.md

@@ -33,6 +33,7 @@ Here's a quick overview of the changes in Fiber `v3`:
   - [Session](#session)
   - [Filesystem](#filesystem)
   - [Monitor](#monitor)
+  - [Healthcheck](#healthcheck)
 - [📋 Migration guide](#-migration-guide)
 
 ## Drop for old Go versions
@@ -330,6 +331,25 @@ DRAFT section
 
 Monitor middleware is now in Contrib package.
 
+### Healthcheck
+
+The Healthcheck middleware has been enhanced to support more than two routes, with default endpoints for liveliness, readiness, and startup checks. Here's a detailed breakdown of the changes and how to use the new features.
+
+1. **Support for More Than Two Routes**:
+   - The updated middleware now supports multiple routes beyond the default liveliness and readiness endpoints. This allows for more granular health checks, such as startup probes.
+
+2. **Default Endpoints**:
+   - Three default endpoints are now available:
+     - **Liveness**: `/livez`
+     - **Readiness**: `/readyz`
+     - **Startup**: `/startupz`
+   - These endpoints can be customized or replaced with user-defined routes.
+
+3. **Simplified Configuration**:
+   - The configuration for each health check endpoint has been simplified. Each endpoint can be configured separately, allowing for more flexibility and readability.
+
+Refer to the [healthcheck middleware migration guide](./middleware/healthcheck.md) or the [general migration guide](#-migration-guide) to review the changes.
+
 ## 📋 Migration guide
 
 - [🚀 App](#-app-1)
@@ -480,3 +500,48 @@ app.Use(static.New("", static.Config{
   MaxAge:       3600,
 }))
 ```
+
+### Healthcheck
+
+Previously, the Healthcheck middleware was configured with a combined setup for liveliness and readiness probes:
+
+```go
+//before
+app.Use(healthcheck.New(healthcheck.Config{
+  LivenessProbe: func(c *fiber.Ctx) bool {
+    return true
+  },
+  LivenessEndpoint: "/live",
+  ReadinessProbe: func(c *fiber.Ctx) bool {
+    return serviceA.Ready() && serviceB.Ready() && ...
+  },
+  ReadinessEndpoint: "/ready",
+}))
+```
+
+With the new version, each health check endpoint is configured separately, allowing for more flexibility:
+
+```go
+// after
+
+// Default liveness endpoint configuration
+app.Get(healthcheck.DefaultLivenessEndpoint, healthcheck.NewHealthChecker(healthcheck.Config{
+  Probe: func(c *fiber.Ctx) bool {
+    return true
+  },
+}))
+
+// Default readiness endpoint configuration
+app.Get(healthcheck.DefaultReadinessEndpoint, healthcheck.NewHealthChecker())
+
+// New default startup endpoint configuration
+// Default endpoint is /startupz
+app.Get(healthcheck.DefaultStartupEndpoint, healthcheck.NewHealthChecker(healthcheck.Config{
+  Probe: func(c *fiber.Ctx) bool {
+    return serviceA.Ready() && serviceB.Ready() && ...
+  },
+}))
+
+// Custom liveness endpoint configuration
+app.Get("/live", healthcheck.NewHealthChecker())
+```

middleware/healthcheck/config.go

@@ -24,6 +24,7 @@ type Config struct {
 const (
 	DefaultLivenessEndpoint  = "/livez"
 	DefaultReadinessEndpoint = "/readyz"
+	DefaultStartupEndpoint   = "/startupz"
 )
 
 func defaultProbe(fiber.Ctx) bool { return true }

middleware/healthcheck/healthcheck_test.go

@@ -34,30 +34,38 @@ func Test_HealthCheck_Strict_Routing_Default(t *testing.T) {
 		StrictRouting: true,
 	})
 
-	app.Get("/livez", NewHealthChecker())
-	app.Get("/readyz", NewHealthChecker())
+	app.Get(DefaultLivenessEndpoint, NewHealthChecker())
+	app.Get(DefaultReadinessEndpoint, NewHealthChecker())
+	app.Get(DefaultStartupEndpoint, NewHealthChecker())
 
 	shouldGiveOK(t, app, "/readyz")
 	shouldGiveOK(t, app, "/livez")
+	shouldGiveOK(t, app, "/startupz")
 	shouldGiveNotFound(t, app, "/readyz/")
 	shouldGiveNotFound(t, app, "/livez/")
+	shouldGiveNotFound(t, app, "/startupz/")
 	shouldGiveNotFound(t, app, "/notDefined/readyz")
 	shouldGiveNotFound(t, app, "/notDefined/livez")
+	shouldGiveNotFound(t, app, "/notDefined/startupz")
 }
 
 func Test_HealthCheck_Default(t *testing.T) {
 	t.Parallel()
 
 	app := fiber.New()
-	app.Get("/livez", NewHealthChecker())
-	app.Get("/readyz", NewHealthChecker())
+	app.Get(DefaultLivenessEndpoint, NewHealthChecker())
+	app.Get(DefaultReadinessEndpoint, NewHealthChecker())
+	app.Get(DefaultStartupEndpoint, NewHealthChecker())
 
 	shouldGiveOK(t, app, "/readyz")
 	shouldGiveOK(t, app, "/livez")
+	shouldGiveOK(t, app, "/startupz")
 	shouldGiveOK(t, app, "/readyz/")
 	shouldGiveOK(t, app, "/livez/")
+	shouldGiveOK(t, app, "/startupz/")
 	shouldGiveNotFound(t, app, "/notDefined/readyz")
 	shouldGiveNotFound(t, app, "/notDefined/livez")
+	shouldGiveNotFound(t, app, "/notDefined/startupz")
 }
 
 func Test_HealthCheck_Custom(t *testing.T) {
@@ -80,6 +88,11 @@ func Test_HealthCheck_Custom(t *testing.T) {
 			}
 		},
 	}))
+	app.Get(DefaultStartupEndpoint, NewHealthChecker(Config{
+		Probe: func(_ fiber.Ctx) bool {
+			return false
+		},
+	}))
 
 	// Setup custom liveness and readiness probes to simulate application health status
 	// Live should return 200 with GET request
@@ -97,6 +110,8 @@ func Test_HealthCheck_Custom(t *testing.T) {
 	// Ready should return 503 with GET request before the channel is closed
 	shouldGiveStatus(t, app, "/ready", fiber.StatusServiceUnavailable)
 
+	shouldGiveStatus(t, app, "/startupz", fiber.StatusServiceUnavailable)
+
 	// Ready should return 200 with GET request after the channel is closed
 	c1 <- struct{}{}
 	shouldGiveOK(t, app, "/ready")
@@ -155,20 +170,23 @@ func Test_HealthCheck_Next(t *testing.T) {
 		},
 	})
 
-	app.Get("/readyz", checker)
-	app.Get("/livez", checker)
+	app.Get(DefaultLivenessEndpoint, checker)
+	app.Get(DefaultReadinessEndpoint, checker)
+	app.Get(DefaultStartupEndpoint, checker)
 
 	// This should give not found since there are no other handlers to execute
 	// so it's like the route isn't defined at all
 	shouldGiveNotFound(t, app, "/readyz")
 	shouldGiveNotFound(t, app, "/livez")
+	shouldGiveNotFound(t, app, "/startupz")
 }
 
 func Benchmark_HealthCheck(b *testing.B) {
 	app := fiber.New()
 
 	app.Get(DefaultLivenessEndpoint, NewHealthChecker())
 	app.Get(DefaultReadinessEndpoint, NewHealthChecker())
+	app.Get(DefaultStartupEndpoint, NewHealthChecker())
 
 	h := app.Handler()
 	fctx := &fasthttp.RequestCtx{}
@@ -190,6 +208,7 @@ func Benchmark_HealthCheck_Parallel(b *testing.B) {
 
 	app.Get(DefaultLivenessEndpoint, NewHealthChecker())
 	app.Get(DefaultReadinessEndpoint, NewHealthChecker())
+	app.Get(DefaultStartupEndpoint, NewHealthChecker())
 
 	h := app.Handler()