write health check endpoints if the service has no HTTP server - go

Question

I want to write health check endpoints for 2 different services, but the problem is they have no HTTP server.
if I can write health check endpoints how can I proceed. or is it mandatory to have an HTTP server to work on health check endpoints with Golang.

Answer 1

Yes, you can add an HTTP health check handler to your application with something like this. Then, in the service that's performing the health check, just make sure it knows which port to run the HTTP checks against.
package main
import "net/http"
func main() {
// Start the health check endpoint and make sure not to block
go func() {
_ = http.ListenAndServe(":8080", http.HandlerFunc(
func(w http.ResponseWriter, r *http.Request) {
_, _ = w.Write([]byte("ok"))
},
))
}()
// Start my application code
}
Alternatively, if you need to expose your health check route at a separate path, you can do something like this.
http.HandleFunc("/health", func(w http.ResponseWriter, r *http.Request) {
_, _ = w.Write([]byte("ok"))
})
_ = http.ListenAndServe(":8080", nil)
Updated
If you want to check the health of a go-routine, you can do something like this.
package main
func main() {
crashed := make(chan struct{})
go func() {
defer close(crashed)
}()
select {
case <-crashed:
// Do something now that the go-routine crashed
}
}

Answer 2

It's not mandatory to have an HTTP server.
You can ping the IP address of your service server. For example I use ping repo:
package main
import (
"fmt"
"time"
"github.com/go-ping/ping"
)
func main() {
t := time.NewTicker(5 * time.Second)
for {
select {
case <-t.C:
err := checkService("google", "216.239.38.120")
if err != nil {
fmt.Println("notif to email, error:", err.Error())
time.Sleep(1 * time.Hour) // to not spam email
}
}
}
}
func checkService(name string, ip string) error {
p, err := ping.NewPinger(ip)
if err != nil {
return err
}
p.Count = 3
p.Timeout = 5 * time.Second
err = p.Run()
if err != nil {
return err
}
stats := p.Statistics()
if stats.PacketLoss == 100 {
return fmt.Errorf("service %s down", name)
}
fmt.Printf("stats: %#v\n", stats)
return nil
}