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handler.go
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handler.go
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// Licensed to Elasticsearch B.V. under one or more contributor
// license agreements. See the NOTICE file distributed with
// this work for additional information regarding copyright
// ownership. Elasticsearch B.V. licenses this file to you under
// the Apache License, Version 2.0 (the "License"); you may
// not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing,
// software distributed under the License is distributed on an
// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
// KIND, either express or implied. See the License for the
// specific language governing permissions and limitations
// under the License.
package apmhttprouter
import (
"net/http"
"github.com/julienschmidt/httprouter"
"go.elastic.co/apm"
"go.elastic.co/apm/module/apmhttp"
)
// Wrap wraps h such that it will report requests as transactions
// to Elastic APM, using route in the transaction name.
//
// By default, the returned Handle will use apm.DefaultTracer.
// Use WithTracer to specify an alternative tracer.
//
// By default, the returned Handle will recover panics, reporting
// them to the configured tracer. To override this behaviour, use
// WithRecovery.
func Wrap(h httprouter.Handle, route string, o ...Option) httprouter.Handle {
opts := gatherOptions(o...)
return func(w http.ResponseWriter, req *http.Request, p httprouter.Params) {
if !opts.tracer.Recording() || opts.requestIgnorer(req) {
h(w, req, p)
return
}
tx, req := apmhttp.StartTransaction(opts.tracer, req.Method+" "+route, req)
defer tx.End()
body := opts.tracer.CaptureHTTPRequestBody(req)
w, resp := apmhttp.WrapResponseWriter(w)
defer func() {
if v := recover(); v != nil {
if resp.StatusCode == 0 {
w.WriteHeader(http.StatusInternalServerError)
}
opts.recovery(w, req, resp, body, tx, v)
}
apmhttp.SetTransactionContext(tx, req, resp, body)
body.Discard()
}()
h(w, req, p)
if resp.StatusCode == 0 {
resp.StatusCode = http.StatusOK
}
}
}
// WrapNotFoundHandler wraps h so that it is traced. If h is nil, then http.NotFoundHandler() will be used.
func WrapNotFoundHandler(h http.Handler, o ...Option) http.Handler {
if h == nil {
h = http.NotFoundHandler()
}
return wrapHandlerUnknownRoute(h, o...)
}
// WrapMethodNotAllowedHandler wraps h so that it is traced. If h is nil, then a default handler
// will be used that returns status code 405.
func WrapMethodNotAllowedHandler(h http.Handler, o ...Option) http.Handler {
if h == nil {
h = http.HandlerFunc(func(w http.ResponseWriter, req *http.Request) {
http.Error(w, http.StatusText(http.StatusMethodNotAllowed), http.StatusMethodNotAllowed)
})
}
return wrapHandlerUnknownRoute(h, o...)
}
func wrapHandlerUnknownRoute(h http.Handler, o ...Option) http.Handler {
opts := gatherOptions(o...)
return apmhttp.Wrap(
h,
apmhttp.WithTracer(opts.tracer),
apmhttp.WithRecovery(opts.recovery),
apmhttp.WithServerRequestName(apmhttp.UnknownRouteRequestName),
apmhttp.WithServerRequestIgnorer(opts.requestIgnorer),
)
}
func gatherOptions(o ...Option) options {
opts := options{
tracer: apm.DefaultTracer,
requestIgnorer: apmhttp.DefaultServerRequestIgnorer(),
}
for _, o := range o {
o(&opts)
}
if opts.recovery == nil {
opts.recovery = apmhttp.NewTraceRecovery(opts.tracer)
}
return opts
}
type options struct {
tracer *apm.Tracer
recovery apmhttp.RecoveryFunc
requestIgnorer apmhttp.RequestIgnorerFunc
}
// Option sets options for tracing.
type Option func(*options)
// WithTracer returns an Option which sets t as the tracer
// to use for tracing server requests.
func WithTracer(t *apm.Tracer) Option {
if t == nil {
panic("t == nil")
}
return func(o *options) {
o.tracer = t
}
}
// WithRecovery returns an Option which sets r as the recovery
// function to use for tracing server requests.
func WithRecovery(r apmhttp.RecoveryFunc) Option {
if r == nil {
panic("r == nil")
}
return func(o *options) {
o.recovery = r
}
}
// WithRequestIgnorer returns a Option which sets r as the
// function to use to determine whether or not a request should
// be ignored. If r is nil, all requests will be reported.
func WithRequestIgnorer(r apmhttp.RequestIgnorerFunc) Option {
if r == nil {
r = apmhttp.IgnoreNone
}
return func(o *options) {
o.requestIgnorer = r
}
}