healthcheck.md

id
healthcheck

Health Check

Liveness, readiness and startup probes middleware for Fiber that provides three endpoints for checking the liveness, readiness, and startup state of HTTP applications.

Overview

• Liveness Probe: Checks if the server is up and running.

  • Default Endpoint: /livez
  • Behavior: By default returns true immediately when the server is operational.

• Readiness Probe: Assesses if the application is ready to handle requests.

  • 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.

Signatures

func NewHealthChecker(config Config) fiber.Handler

Examples

Import the middleware package that is part of the Fiber web framework

import(
    "github.com/gofiber/fiber/v3"
    "github.com/gofiber/fiber/v3/middleware/healthcheck"
)

After you initiate your Fiber app, you can use the following possibilities:

// Provide a minimal config for liveness check
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())

// Or extend your config for customization
app.Get(healthcheck.DefaultLivenessEndpoint, healthcheck.NewHealthChecker(healthcheck.Config{
    Probe: func(c fiber.Ctx) bool {
        return true
    },
}))
// And it works the same for readiness, just change the route
app.Get(healthcheck.DefaultReadinessEndpoint, healthcheck.NewHealthChecker(healthcheck.Config{
    Probe: func(c fiber.Ctx) bool {
        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 {
        return true
    },
}))

// It can also be used with app.All, although it will only respond to requests with the GET method
// in case of calling the route with any method which isn't GET, the return will be 404 Not Found when app.All is used
// and 405 Method Not Allowed when app.Get is used
app.All(healthcheck.DefaultReadinessEndpoint, healthcheck.NewHealthChecker(healthcheck.Config{
    Probe: func(c fiber.Ctx) bool {
        return true
    },
}))

Config

type Config struct {
    // Next defines a function to skip this middleware when returned true. If this function returns true
    // and no other handlers are defined for the route, Fiber will return a status 404 Not Found, since
    // no other handlers were defined to return a different status.
    //
    // Optional. Default: nil
    Next func(fiber.Ctx) bool

    // 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
}

Default Config

The default configuration used by this middleware is defined as follows:

func defaultProbe(fiber.Ctx) bool { return true }

var ConfigDefault = Config{
    Probe:     defaultProbe,
}