go-promhttp

go-promhttp provides wrappers around the http package objects for monitoring with Prometheus, namely the http.Client, and http.Handler.

Requirements

minimum golang version of 1.9

Wrapping the http.Client

For example, you can instrument your http requests sent using the promhttp.Client as follows:

httpClient := &promhttp.Client{
	Client: http.DefaultClient,
	Registerer: prometheus.DefaultRegister,
}
githubClient, _ := httpClient.ForRecipient("github")

resp, err := githubClient.Get("https://api.github.com/repos/travelaudience/go-promhttp/issues")
...

Doing so will give you prometheus metrics such as:

metric	description
requests_total	A counter for outgoing requests.
request_duration_histogram_seconds	A histogram of outgoing request latencies.
dns_duration_histogram_seconds	Trace dns latency histogram.
tls_duration_histogram_seconds	Trace tls latency histogram.
in_flight_requests	A gauge of in-flight outgoing requests.

By calling httpClient.ForRecipient("github"), all of these metrics will be tagged with the label "recipient": "github"

Wrapping the http.Handler

Simmilarly, a http.Handler can be instrumented for monitoring via the promhttp.ServeMux. By running the following code,

mux := &promhttp.ServeMux {
	ServeMux: &http.ServeMux{}
}

mux.Handle("/issues", http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
	...
}))

we have the mux handle incoming requests and generating metrics. The metrics generated are as follows:

metric	description
request_duration_histogram_seconds	The request time duration .
requests_total	The total number of requests received.
request_size_histogram_bytes	The request size in bytes.
response_size_histogram_bytes	Thes response size in bytes.
in_flight_requests	The number of http requests which are currently running.

And all of these metrics in our example would have the label "path": "/issues".

Contributing

Contributions are welcomed! Read the Contributing Guide for more information.

Licensing

This project is licensed under the MIT License - see the LICENSE file for details