healthz

healthz is a simple package to add liveness and readiness probes to your application, primarily for kubernetes support

Probes are defined as type CheckFunc func() bool. If this function returns true, the probe passes.

healthz will expose two HTTP endpoints:

• /healthz/alive
• /healthz/ready

By default, both use a simple check that always returns true. For passsing probes, the endpoints return 200 OK. For failing probes the endpoints return 503 Service Unavailable.

Example usage

The following code is from example/example.go

package main

import (
	"fmt"
	"net/http"
	"os"
	"os/signal"
	"syscall"
	"time"

	"github.com/jasongerard/healthz"
)

var ready = false

func main() {

	errs := make(chan error, 2)

	// setup signal handler (capture CTRL+C)
	go func() {
		signalChan := make(chan os.Signal)
		signal.Notify(signalChan, syscall.SIGINT)
		errs <- fmt.Errorf("%s", <-signalChan)
	}()

	// set up our healthcheck server
	go func() {
		healthz.ReadinessCheck(func() bool {
			return ready
		})

		mux := healthz.CreateMux()
		srv := &http.Server{
			Handler: mux,
			Addr:    ":8123",
		}

		errs <- srv.ListenAndServe()
	}()

	// set up useful stuff for your app to do here
	// simulate work
	time.Sleep(5 * time.Second)

	// set up is done, mark app as ready
	ready = true

	// block on errs channel until we get a SIGINT or the HTTP server exits
	fmt.Printf("program terminating: %v\n", <-errs)

	// any requests to http://localhost:8123/healthz/ready will return 503 for the first 5 seconds
	// and then begin returning 200 OK
	// run and test with `while true; do curl -I http://localhost:8123/healthz/ready; sleep 1; done`
}