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Add http.Handler helpers (adapted from xlog)

This commit is contained in:
Olivier Poitrey 2017-05-20 01:48:00 -07:00
parent 3f54be8716
commit 6a6144a10b
7 changed files with 438 additions and 4 deletions
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43
README.md
View File

@ -9,6 +9,8 @@ The zerolog package provides a fast and simple logger dedicated to JSON output.
* Level logging
* Sampling
* Contextual fields
* `context.Context` integration
* `net/http` helpers
## Performance
@ -200,6 +202,47 @@ log.Ctx(ctx).Info().Msg("hello world")
// Output: {"component":"module","level":"info","message":"hello world"}
```
### Integration with `net/http`
The `github.com/rs/zerolog/hlog` package provides some helpers to integrate zerolog with `http.Handler`.
In this example we use [alice](github.com/justinas/alice) to install logger for better readability.
```go
log := zerolog.New(os.Stdout).With().
Str("role", "my-service").
Str("host", host).
Logger()
c := alice.New()
// 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)
if err := http.ListenAndServe(":8080", nil); err != nil {
log.Fatal().Err(err).Msg("Startup failed")
}
```
## Global Settings
Some settings can be changed and will by applied to all loggers:

11
ctx.go
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@ -11,14 +11,19 @@ type ctxKey struct{}
// WithContext returns a copy of ctx with l associated.
func (l Logger) WithContext(ctx context.Context) context.Context {
return context.WithValue(ctx, ctxKey{}, l)
if lp, ok := ctx.Value(ctxKey{}).(*Logger); ok {
// Update existing pointer.
*lp = l
return ctx
}
return context.WithValue(ctx, ctxKey{}, &l)
}
// Ctx returns the Logger associated with the ctx. If no logger
// is associated, a disabled logger is returned.
func Ctx(ctx context.Context) Logger {
if l, ok := ctx.Value(ctxKey{}).(Logger); ok {
return l
if l, ok := ctx.Value(ctxKey{}).(*Logger); ok {
return *l
}
return disabledLogger
}

8
ctx_test.go
View File

@ -15,6 +15,14 @@ func TestCtx(t *testing.T) {
t.Error("Ctx did not return the expected logger")
}
// update
log = log.Level(InfoLevel)
ctx = log.WithContext(ctx)
log2 = Ctx(ctx)
if !reflect.DeepEqual(log, log2) {
t.Error("Ctx did not return the expected logger")
}
log2 = Ctx(context.Background())
if !reflect.DeepEqual(log2, disabledLogger) {
t.Error("Ctx did not return the expected logger")

154
hlog/hlog.go Normal file
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@ -0,0 +1,154 @@
// Package hlog provides a set of http.Handler helpers for zerolog.
package hlog
import (
"context"
"net"
"net/http"
"github.com/rs/xid"
"github.com/rs/zerolog"
"github.com/rs/zerolog/log"
)
// FromRequest gets the logger in the request's context.
// This is a shortcut for log.Ctx(r.Context())
func FromRequest(r *http.Request) zerolog.Logger {
return log.Ctx(r.Context())
}
// NewHandler injects log into requests context.
func NewHandler(log zerolog.Logger) func(http.Handler) http.Handler {
return func(next http.Handler) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
r = r.WithContext(log.WithContext(r.Context()))
next.ServeHTTP(w, r)
})
}
}
// URLHandler adds the requested URL as a field to the context's logger
// using fieldKey as field key.
func URLHandler(fieldKey string) func(next http.Handler) http.Handler {
return func(next http.Handler) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
log := zerolog.Ctx(r.Context())
log = log.With().Str(fieldKey, r.URL.String()).Logger()
r = r.WithContext(log.WithContext(r.Context()))
next.ServeHTTP(w, r)
})
}
}
// MethodHandler adds the request method as a field to the context's logger
// using fieldKey as field key.
func MethodHandler(fieldKey string) func(next http.Handler) http.Handler {
return func(next http.Handler) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
log := zerolog.Ctx(r.Context())
log = log.With().Str(fieldKey, r.Method).Logger()
r = r.WithContext(log.WithContext(r.Context()))
next.ServeHTTP(w, r)
})
}
}
// RequestHandler adds the request method and URL as a field to the context's logger
// using fieldKey as field key.
func RequestHandler(fieldKey string) func(next http.Handler) http.Handler {
return func(next http.Handler) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
log := zerolog.Ctx(r.Context())
log = log.With().Str(fieldKey, r.Method+" "+r.URL.String()).Logger()
r = r.WithContext(log.WithContext(r.Context()))
next.ServeHTTP(w, r)
})
}
}
// RemoteAddrHandler adds the request's remote address as a field to the context's logger
// using fieldKey as field key.
func RemoteAddrHandler(fieldKey string) func(next http.Handler) http.Handler {
return func(next http.Handler) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
if host, _, err := net.SplitHostPort(r.RemoteAddr); err == nil {
log := zerolog.Ctx(r.Context())
log = log.With().Str(fieldKey, host).Logger()
r = r.WithContext(log.WithContext(r.Context()))
}
next.ServeHTTP(w, r)
})
}
}
// UserAgentHandler adds the request's user-agent as a field to the context's logger
// using fieldKey as field key.
func UserAgentHandler(fieldKey string) func(next http.Handler) http.Handler {
return func(next http.Handler) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
if ua := r.Header.Get("User-Agent"); ua != "" {
log := zerolog.Ctx(r.Context())
log = log.With().Str(fieldKey, ua).Logger()
r = r.WithContext(log.WithContext(r.Context()))
}
next.ServeHTTP(w, r)
})
}
}
// RefererHandler adds the request's referer as a field to the context's logger
// using fieldKey as field key.
func RefererHandler(fieldKey string) func(next http.Handler) http.Handler {
return func(next http.Handler) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
if ref := r.Header.Get("Referer"); ref != "" {
log := zerolog.Ctx(r.Context())
log = log.With().Str(fieldKey, ref).Logger()
r = r.WithContext(log.WithContext(r.Context()))
}
next.ServeHTTP(w, r)
})
}
}
type idKey struct{}
// IDFromRequest returns the unique id accociated to the request if any.
func IDFromRequest(r *http.Request) (id xid.ID, ok bool) {
if r == nil {
return
}
id, ok = r.Context().Value(idKey{}).(xid.ID)
return
}
// 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 RequestIDHandler(fieldKey, headerName string) func(next http.Handler) http.Handler {
return func(next http.Handler) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
id, ok := IDFromRequest(r)
if !ok {
id = xid.New()
ctx := context.WithValue(r.Context(), idKey{}, id)
r = r.WithContext(ctx)
}
if fieldKey != "" {
log := zerolog.Ctx(r.Context())
log = log.With().Str(fieldKey, id.String()).Logger()
r = r.WithContext(log.WithContext(r.Context()))
}
if headerName != "" {
w.Header().Set(headerName, id.String())
}
next.ServeHTTP(w, r)
})
}
}

51
hlog/hlog_example_test.go Normal file
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@ -0,0 +1,51 @@
package hlog_test
import (
"net/http"
"os"
"github.com/rs/zerolog"
"github.com/rs/zerolog/hlog"
)
// fake alice to avoid dep
type alice struct{}
func (a alice) Append(interface{}) alice { return a }
func (alice) Then(h http.Handler) http.Handler { return h }
func Example_handler() {
host, _ := os.Hostname()
log := zerolog.New(os.Stdout).With().
Str("role", "my-service").
Str("host", host).
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)
if err := http.ListenAndServe(":8080", nil); err != nil {
log.Fatal().Err(err).Msg("Startup failed")
}
}

173
hlog/hlog_test.go Normal file
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@ -0,0 +1,173 @@
// +build go1.7
package hlog
import (
"bytes"
"fmt"
"net/http"
"net/url"
"testing"
"reflect"
"net/http/httptest"
"github.com/rs/zerolog"
)
func TestNewHandler(t *testing.T) {
log := zerolog.New(nil).With().
Str("foo", "bar").
Logger()
lh := NewHandler(log)
h := lh(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
l := FromRequest(r)
if !reflect.DeepEqual(l, log) {
t.Fail()
}
}))
h.ServeHTTP(nil, &http.Request{})
}
func TestURLHandler(t *testing.T) {
out := &bytes.Buffer{}
r := &http.Request{
URL: &url.URL{Path: "/path", RawQuery: "foo=bar"},
}
h := URLHandler("url")(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
l := FromRequest(r)
l.Log().Msg("")
if want, got := `{"url":"/path?foo=bar"}`+"\n", out.String(); want != got {
t.Errorf("Invalid log output, got: %s, want: %s", got, want)
}
}))
h = NewHandler(zerolog.New(out))(h)
h.ServeHTTP(nil, r)
}
func TestMethodHandler(t *testing.T) {
out := &bytes.Buffer{}
r := &http.Request{
Method: "POST",
}
h := MethodHandler("method")(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
l := FromRequest(r)
l.Log().Msg("")
if want, got := `{"method":"POST"}`+"\n", out.String(); want != got {
t.Errorf("Invalid log output, got: %s, want: %s", got, want)
}
}))
h = NewHandler(zerolog.New(out))(h)
h.ServeHTTP(nil, r)
}
func TestRequestHandler(t *testing.T) {
out := &bytes.Buffer{}
r := &http.Request{
Method: "POST",
URL: &url.URL{Path: "/path", RawQuery: "foo=bar"},
}
h := RequestHandler("request")(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
l := FromRequest(r)
l.Log().Msg("")
if want, got := `{"request":"POST /path?foo=bar"}`+"\n", out.String(); want != got {
t.Errorf("Invalid log output, got: %s, want: %s", got, want)
}
}))
h = NewHandler(zerolog.New(out))(h)
h.ServeHTTP(nil, r)
}
func TestRemoteAddrHandler(t *testing.T) {
out := &bytes.Buffer{}
r := &http.Request{
RemoteAddr: "1.2.3.4:1234",
}
h := RemoteAddrHandler("ip")(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
l := FromRequest(r)
l.Log().Msg("")
if want, got := `{"ip":"1.2.3.4"}`+"\n", out.String(); want != got {
t.Errorf("Invalid log output, got: %s, want: %s", got, want)
}
}))
h = NewHandler(zerolog.New(out))(h)
h.ServeHTTP(nil, r)
}
func TestRemoteAddrHandlerIPv6(t *testing.T) {
out := &bytes.Buffer{}
r := &http.Request{
RemoteAddr: "[2001:db8:a0b:12f0::1]:1234",
}
h := RemoteAddrHandler("ip")(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
l := FromRequest(r)
l.Log().Msg("")
if want, got := `{"ip":"2001:db8:a0b:12f0::1"}`+"\n", out.String(); want != got {
t.Errorf("Invalid log output, got: %s, want: %s", got, want)
}
}))
h = NewHandler(zerolog.New(out))(h)
h.ServeHTTP(nil, r)
}
func TestUserAgentHandler(t *testing.T) {
out := &bytes.Buffer{}
r := &http.Request{
Header: http.Header{
"User-Agent": []string{"some user agent string"},
},
}
h := UserAgentHandler("ua")(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
l := FromRequest(r)
l.Log().Msg("")
if want, got := `{"ua":"some user agent string"}`+"\n", out.String(); want != got {
t.Errorf("Invalid log output, got: %s, want: %s", got, want)
}
}))
h = NewHandler(zerolog.New(out))(h)
h.ServeHTTP(nil, r)
}
func TestRefererHandler(t *testing.T) {
out := &bytes.Buffer{}
r := &http.Request{
Header: http.Header{
"Referer": []string{"http://foo.com/bar"},
},
}
h := RefererHandler("referer")(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
l := FromRequest(r)
l.Log().Msg("")
if want, got := `{"referer":"http://foo.com/bar"}`+"\n", out.String(); want != got {
t.Errorf("Invalid log output, got: %s, want: %s", got, want)
}
}))
h = NewHandler(zerolog.New(out))(h)
h.ServeHTTP(nil, r)
}
func TestRequestIDHandler(t *testing.T) {
out := &bytes.Buffer{}
r := &http.Request{
Header: http.Header{
"Referer": []string{"http://foo.com/bar"},
},
}
h := RequestIDHandler("id", "Request-Id")(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
id, ok := IDFromRequest(r)
if !ok {
t.Fatal("Missing id in request")
}
if want, got := id.String(), w.Header().Get("Request-Id"); got != want {
t.Errorf("Invalid Request-Id header, got: %s, want: %s", got, want)
}
l := FromRequest(r)
l.Log().Msg("")
if want, got := fmt.Sprintf(`{"id":"%s"}`+"\n", id), out.String(); want != got {
t.Errorf("Invalid log output, got: %s, want: %s", got, want)
}
}))
h = NewHandler(zerolog.New(out))(h)
h.ServeHTTP(httptest.NewRecorder(), r)
}

2
log.go
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@ -145,7 +145,7 @@ type Logger struct {
// you may consider using sync wrapper.
func New(w io.Writer) Logger {
if w == nil {
panic("w is nil")
w = ioutil.Discard
}
lw, ok := w.(LevelWriter)
if !ok {