httpmetrics

Documentation

Overview

Package httpmetrics provides middleware for collecting metrics about http servers.

Metrics are prefixed with:

http.server.<method>.<normalized path>
http.server.all

For example, a request to GET /apps/:foo/bars/:bar_id emits metrics prefixed with:

http.server.get.apps.foo.bars.bar-id
http.server.all

For each unique path, and under the global all prefix, servers will report:

requests - counter of requests
request-duration.ms - histogram of request durations in milliseconds
response-statuses.<status code> - counter of response status codes, eg 200

Example

This example demonstrates how to set up metrics and what will be collected on requests

package main

import (
	"fmt"
	"net/http"
	"net/http/httptest"
	"testing"

	"github.com/go-chi/chi"

	"github.com/heroku/x/go-kit/metrics/testmetrics"
	"github.com/heroku/x/hmiddleware/httpmetrics"
)

func main() {
	// Create a new Metrics Provider
	provider := testmetrics.NewProvider(&testing.T{})
	r := chi.NewRouter()

	// Use the Metrics Provider to create a new HTTP Handler
	r.Use(httpmetrics.New(provider))

	// Metrics will be collected around http OK statuses
	// For all requests and for /foo requests
	r.Get("/foo", http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		w.WriteHeader(http.StatusOK)
	}))

	// Metrics will be collected around http Bad Request statuses
	// For all requests and for /bar requests
	r.Get("/bar", http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		w.WriteHeader(http.StatusBadRequest)
	}))

	server := httptest.NewServer(r)
	defer server.Close()

	// Metrics will be collected for each request
	req, _ := http.NewRequest("GET", server.URL+"/foo", nil)
	if _, err := http.DefaultClient.Do(req); err != nil {
		fmt.Println(err)
	}

	req, _ = http.NewRequest("GET", server.URL+"/bar", nil)
	if _, err := http.DefaultClient.Do(req); err != nil {
		fmt.Println(err)
	}

	provider.PrintCounterValue("http.server.get.bar.response-statuses.400")
	provider.PrintCounterValue("http.server.all.requests")
	provider.PrintCounterValue("http.server.all.response-statuses.200")
	provider.PrintCounterValue("http.server.get.foo.requests")
	provider.PrintCounterValue("http.server.get.foo.response-statuses.200")
	provider.PrintCounterValue("http.server.all.response-statuses.400")
	provider.PrintCounterValue("http.server.get.bar.requests")

}

Output:

http.server.get.bar.response-statuses.400: 1
http.server.all.requests: 2
http.server.all.response-statuses.200: 1
http.server.get.foo.requests: 1
http.server.get.foo.response-statuses.200: 1
http.server.all.response-statuses.400: 1
http.server.get.bar.requests: 1

Index

• func New(p metrics.Provider) func(http.Handler) http.Handler
• func NewOTEL(p metrics.Provider) func(http.Handler) http.Handler
• func NewServer(p metrics.Provider, next http.Handler) http.Handler

Examples

• Package

Functions

func New

func New(p metrics.Provider) func(http.Handler) http.Handler

New returns an HTTP middleware which captures request metrics and reports them to the given provider.

func NewOTEL

func NewOTEL(p metrics.Provider) func(http.Handler) http.Handler

NewOTEL returns an HTTP middleware which captures HTTP request counts and latency annotated with attributes for method, route, status.

See https://opentelemetry.io/docs/specs/otel/metrics/semantic_conventions/http-metrics/

func NewServer

func NewServer(p metrics.Provider, next http.Handler) http.Handler

NewServer returns an http.Handler which calls next for each request and reports metrics to the given provider.

Deprecated: NewServer is awkward to use since it doesn't follow the normal pattern for middleware. Use New instead.