hlog

Documentation

Overview

Package hlog provides a set of http.Handler helpers for zerolog.

Example (Handler)

//go:build !binary_log
// +build !binary_log

package main

import (
	"net/http"
	"os"
	"time"

	"net/http/httptest"

	"github.com/rs/zerolog"
	"github.com/rs/zerolog/hlog"
)

// fake alice to avoid dep
type middleware func(http.Handler) http.Handler
type alice struct {
	m []middleware
}

func (a alice) Append(m middleware) alice {
	a.m = append(a.m, m)
	return a
}
func (a alice) Then(h http.Handler) http.Handler {
	for i := range a.m {
		h = a.m[len(a.m)-1-i](h)
	}
	return h
}

func init() {
	zerolog.TimestampFunc = func() time.Time {
		return time.Date(2001, time.February, 3, 4, 5, 6, 7, time.UTC)
	}
}

func main() {
	log := zerolog.New(os.Stdout).With().
		Timestamp().
		Str("role", "my-service").
		Str("host", "local-hostname").
		Logger()

	c := alice{}

	// Install the logger handler with default output on the console
	c = c.Append(hlog.NewHandler(log))

	// Install some provided extra handler to set some request's context fields.
	// Thanks to those handler, all our logs will come with some pre-populated fields.
	c = c.Append(hlog.RemoteAddrHandler("ip"))
	c = c.Append(hlog.UserAgentHandler("user_agent"))
	c = c.Append(hlog.RefererHandler("referer"))
	//c = c.Append(hlog.RequestIDHandler("req_id", "Request-Id"))

	// Here is your final handler
	h := c.Then(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		// Get the logger from the request's context. You can safely assume it
		// will be always there: if the handler is removed, hlog.FromRequest
		// will return a no-op logger.
		hlog.FromRequest(r).Info().
			Str("user", "current user").
			Str("status", "ok").
			Msg("Something happend")
	}))
	http.Handle("/", h)

	h.ServeHTTP(httptest.NewRecorder(), &http.Request{})

}

Output:

{"level":"info","role":"my-service","host":"local-hostname","user":"current user","status":"ok","time":"2001-02-03T04:05:06Z","message":"Something happend"}

Index

• func AccessHandler(f func(r *http.Request, status, size int, duration time.Duration)) func(next http.Handler) http.Handler
• func FromRequest(r *http.Request) *zerolog.Logger
• func IDFromCtx(ctx context.Context) (id xid.ID, ok bool)
• func IDFromRequest(r *http.Request) (id xid.ID, ok bool)
• func MethodHandler(fieldKey string) func(next http.Handler) http.Handler
• func NewHandler(log zerolog.Logger) func(http.Handler) http.Handler
• func RefererHandler(fieldKey string) func(next http.Handler) http.Handler
• func RemoteAddrHandler(fieldKey string) func(next http.Handler) http.Handler
• func RequestHandler(fieldKey string) func(next http.Handler) http.Handler
• func RequestIDHandler(fieldKey, headerName string) func(next http.Handler) http.Handler
• func URLHandler(fieldKey string) func(next http.Handler) http.Handler
• func UserAgentHandler(fieldKey string) func(next http.Handler) http.Handler

Examples

• Package (Handler)

Functions

func AccessHandler

func AccessHandler(f func(r *http.Request, status, size int, duration time.Duration)) func(next http.Handler) http.Handler

AccessHandler returns a handler that call f after each request.

func FromRequest

func FromRequest(r *http.Request) *zerolog.Logger

FromRequest gets the logger in the request's context. This is a shortcut for log.Ctx(r.Context())

func IDFromCtx

func IDFromCtx(ctx context.Context) (id xid.ID, ok bool)

IDFromCtx returns the unique id associated to the context if any.

func IDFromRequest

func IDFromRequest(r *http.Request) (id xid.ID, ok bool)

IDFromRequest returns the unique id associated to the request if any.

func MethodHandler

func MethodHandler(fieldKey string) func(next http.Handler) http.Handler

MethodHandler adds the request method as a field to the context's logger using fieldKey as field key.

func NewHandler

func NewHandler(log zerolog.Logger) func(http.Handler) http.Handler

NewHandler injects log into requests context.

func RefererHandler

func RefererHandler(fieldKey string) func(next http.Handler) http.Handler

RefererHandler adds the request's referer as a field to the context's logger using fieldKey as field key.

func RemoteAddrHandler

func RemoteAddrHandler(fieldKey string) func(next http.Handler) http.Handler

RemoteAddrHandler adds the request's remote address as a field to the context's logger using fieldKey as field key.

func RequestHandler

func RequestHandler(fieldKey string) func(next http.Handler) http.Handler

RequestHandler adds the request method and URL as a field to the context's logger using fieldKey as field key.

func RequestIDHandler

func RequestIDHandler(fieldKey, headerName string) func(next http.Handler) http.Handler

RequestIDHandler returns a handler setting a unique id to the request which can be gathered using IDFromRequest(req). This generated id is added as a field to the logger using the passed fieldKey as field name. The id is also added as a response header if the headerName is not empty.

The generated id is a URL safe base64 encoded mongo object-id-like unique id. Mongo unique id generation algorithm has been selected as a trade-off between size and ease of use: UUID is less space efficient and snowflake requires machine configuration.

func URLHandler

func URLHandler(fieldKey string) func(next http.Handler) http.Handler

URLHandler adds the requested URL as a field to the context's logger using fieldKey as field key.

func UserAgentHandler

func UserAgentHandler(fieldKey string) func(next http.Handler) http.Handler

UserAgentHandler adds the request's user-agent as a field to the context's logger using fieldKey as field key.