Go-metrics & healthchecks for microservice(s)

Getting Help
1

Hi All,

I wonder if anyone is using https://github.com/rcrowley/go-metrics to provide metrics and healthcheck status for their app ? If not, what library are you using to provide custom metrics and healtcheck results ?

Using go-metrics is quite straight forward, but I’m having trouble creating a healthcheck :confused: … I’ve tried this :

hc := metrics.NewHealthcheck(func(h metrics.Healthcheck) {
		if 0 < rand.Intn(2) {
			h.Healthy()
		} else {
			h.Unhealthy(errors.New("baz"))
		}
	})
	r.Register("baz", hc)

which I took from here : https://github.com/yowenter/http_ngrok/blob/e625ce5980fefc9700aa4cae15e705d668373f03/src/github.com/inconshreveable/go-metrics/cmd/metrics-example/metrics-example.go#L53

but I then get the following when calling /debug/metrics on my app :

2017/05/05 10:53:12 http: panic serving [::1]:61521: unsupported type for 'baz': *metrics.StandardHealthcheck
goroutine 52 [running]:
net/http.(*conn).serve.func1(0xc4201f80a0)
        /usr/local/go/src/net/http/server.go:1721 +0xd0
panic(0x1450da0, 0xc4201ace60)
        /usr/local/go/src/runtime/panic.go:489 +0x2cf
github.com/rcrowley/go-metrics/exp.(*exp).syncToExpvar.func1(0x14f410e, 0x3, 0x1493860, 0xc4200e1920)
        /Users/ale/projects/go/src/github.com/rcrowley/go-metrics/exp/exp.go:153 +0x501
github.com/rcrowley/go-metrics.(*StandardRegistry).Each(0xc420172260, 0xc4201ace30)
        /Users/ale/projects/go/src/github.com/rcrowley/go-metrics/registry.go:65 +0xc0
github.com/rcrowley/go-metrics/exp.(*exp).syncToExpvar(0xc4200e1900)
        /Users/ale/projects/go/src/github.com/rcrowley/go-metrics/exp/exp.go:155 +0x75
github.com/rcrowley/go-metrics/exp.(*exp).expHandler(0xc4200e1900, 0x1716160, 0xc4201d8380, 0xc42006ad00)
        /Users/ale/projects/go/src/github.com/rcrowley/go-metrics/exp/exp.go:21 +0x35
github.com/rcrowley/go-metrics/exp.(*exp).(github.com/rcrowley/go-metrics/exp.expHandler)-fm(0x1716160, 0xc4201d8380, 0xc42006ad00)
        /Users/ale/projects/go/src/github.com/rcrowley/go-metrics/exp/exp.go:50 +0x48
net/http.HandlerFunc.ServeHTTP(0xc4201722e0, 0x1716160, 0xc4201d8380, 0xc42006ad00)
        /usr/local/go/src/net/http/server.go:1942 +0x44
net/http.(*ServeMux).ServeHTTP(0x1745e20, 0x1716160, 0xc4201d8380, 0xc42006ad00)
        /usr/local/go/src/net/http/server.go:2238 +0x130
net/http.serverHandler.ServeHTTP(0xc42001a0b0, 0x1716160, 0xc4201d8380, 0xc42006ad00)
        /usr/local/go/src/net/http/server.go:2568 +0x92
net/http.(*conn).serve(0xc4201f80a0, 0x17168e0, 0xc4201b3a80)
        /usr/local/go/src/net/http/server.go:1825 +0x612
created by net/http.(*Server).Serve
        /usr/local/go/src/net/http/server.go:2668 +0x2ce

the actual check i want to implement is checking a http endpoint, similar to this :

hc := metrics.NewHealthcheck(func(h metrics.Healthcheck) {
		_, err := http.Get("https://www.google.com")
		if err != nil {
			h.Unhealthy(errors.New("error description or output"))
		} else {
			h.Healthy()
		}
	})
	r.Register("endpoint-X", hc)

both end up in the same error though …

Any help would be really appreciated!

Thanks
Alex

2

Ok, so actually go it not to error by doing :

[...]
	r.Register("endpoint-X", &hc)

and it looks like I need to still invoke it manually …

hc.Check()

but still don’t see it in /debug/metrics

4

Here are some other metrics packages: https://pocketgophers.com/10-to-instrument/

1 Like
5

thanks! I’m having a look just now :slight_smile:

6

Oh, I think I understand now, it won’t be possible to read it via http://host:port/debug/metrics as it’s not being published here https://github.com/rcrowley/go-metrics/blob/master/exp/exp.go#L137 which actually also explains the error.

7

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