/
client.go
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/
client.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.
//go:build go1.9
// +build go1.9
package apmgrpc // import "go.elastic.co/apm/module/apmgrpc"
import (
"net"
"net/http"
"net/url"
"sync"
"golang.org/x/net/context"
"google.golang.org/grpc"
"google.golang.org/grpc/codes"
"google.golang.org/grpc/credentials"
"google.golang.org/grpc/metadata"
"google.golang.org/grpc/peer"
"go.elastic.co/apm"
"go.elastic.co/apm/module/apmhttp"
)
// NewUnaryClientInterceptor returns a grpc.UnaryClientInterceptor that
// traces gRPC requests with the given options.
//
// The interceptor will trace spans with the "external.grpc" type for each
// request made, for any client method presented with a context containing
// a sampled apm.Transaction.
func NewUnaryClientInterceptor(o ...ClientOption) grpc.UnaryClientInterceptor {
opts := clientOptions{}
for _, o := range o {
o(&opts)
}
return func(
ctx context.Context,
method string,
req, resp interface{},
cc *grpc.ClientConn,
invoker grpc.UnaryInvoker,
opts ...grpc.CallOption,
) error {
var peer peer.Peer // maybe set after call if span != nil
var header metadata.MD // maybe set after call if span != nil
span, ctx := startSpan(ctx, method)
if span != nil {
defer span.End()
opts = append(opts, grpc.Peer(&peer), grpc.Header(&header))
}
err := invoker(ctx, method, req, resp, cc, opts...)
if span != nil {
setSpanOutcome(span, err)
url := url.URL{Scheme: "http", Path: method}
if _, ok := peer.AuthInfo.(credentials.TLSInfo); ok {
url.Scheme = "https"
}
if peer.Addr != nil {
url.Host = peer.Addr.String()
}
span.Context.SetHTTPRequest(&http.Request{
URL: &url,
Method: "POST", // method is always POST
ProtoMajor: 2,
ProtoMinor: 0,
Header: http.Header(header),
})
if url.Host != "" {
span.Context.SetDestinationService(apm.DestinationServiceSpanContext{
Name: url.Host,
Resource: url.Host,
})
}
}
return err
}
}
// NewStreamClientInterceptor returns a grpc.UnaryClientInterceptor that
// traces gRPC requests with the given options.
//
// The interceptor will trace spans with the "external.grpc" type for each
// stream request made, for any client method presented with a context
// containing a sampled apm.Transaction.
//
// Spans are ended when the stream is closed, which can happen in various
// ways: the initial stream setup request fails, Header, SendMsg or RecvMsg
// return with an error, or RecvMsg returns for a non-streaming server.
func NewStreamClientInterceptor(o ...ClientOption) grpc.StreamClientInterceptor {
opts := clientOptions{}
for _, o := range o {
o(&opts)
}
return func(
ctx context.Context,
desc *grpc.StreamDesc,
cc *grpc.ClientConn,
method string,
streamer grpc.Streamer,
opts ...grpc.CallOption,
) (grpc.ClientStream, error) {
var peer peer.Peer
span, ctx := startSpan(ctx, method)
if span != nil {
opts = append(opts, grpc.Peer(&peer))
}
stream, err := streamer(ctx, desc, cc, method, opts...)
if span != nil {
if err != nil {
setSpanOutcome(span, err)
setSpanContext(span, peer)
span.End()
} else if stream != nil {
wrapped := &clientStream{ClientStream: stream}
go func() {
defer span.End()
// Header blocks until headers are available
// or the stream is ended. Either way, after
// Header returns, it is safe to call Context().
stream.Header()
<-stream.Context().Done()
err := wrapped.getError()
setSpanOutcome(span, err)
setSpanContext(span, peer)
}()
stream = wrapped
}
}
return stream, err
}
}
// clientStream wraps grpc.ClientStream to intercept errors.
type clientStream struct {
grpc.ClientStream
mu sync.RWMutex
err error
}
func (s *clientStream) CloseSend() error {
err := s.ClientStream.CloseSend()
s.setError(err)
return err
}
func (s *clientStream) Header() (metadata.MD, error) {
md, err := s.ClientStream.Header()
s.setError(err)
return md, err
}
func (s *clientStream) SendMsg(m interface{}) error {
err := s.ClientStream.SendMsg(m)
s.setError(err)
return err
}
func (s *clientStream) RecvMsg(m interface{}) error {
err := s.ClientStream.RecvMsg(m)
s.setError(err)
return err
}
func (s *clientStream) getError() error {
s.mu.RLock()
defer s.mu.RUnlock()
return s.err
}
func (s *clientStream) setError(err error) {
if err != nil {
s.mu.Lock()
s.err = err
s.mu.Unlock()
}
}
func startSpan(ctx context.Context, name string) (*apm.Span, context.Context) {
tx := apm.TransactionFromContext(ctx)
if tx == nil {
return nil, ctx
}
traceContext := tx.TraceContext()
propagateLegacyHeader := tx.ShouldPropagateLegacyHeader()
if !traceContext.Options.Recorded() {
return nil, outgoingContextWithTraceContext(ctx, traceContext, propagateLegacyHeader)
}
span := tx.StartSpan(name, "external.grpc", apm.SpanFromContext(ctx))
if !span.Dropped() {
traceContext = span.TraceContext()
ctx = apm.ContextWithSpan(ctx, span)
}
return span, outgoingContextWithTraceContext(ctx, traceContext, propagateLegacyHeader)
}
func setSpanContext(span *apm.Span, peer peer.Peer) {
if peer.Addr != nil {
if tcpAddr, ok := peer.Addr.(*net.TCPAddr); ok {
span.Context.SetDestinationAddress(tcpAddr.IP.String(), tcpAddr.Port)
}
addrString := peer.Addr.String()
span.Context.SetDestinationService(apm.DestinationServiceSpanContext{
Name: addrString,
Resource: addrString,
})
}
}
func outgoingContextWithTraceContext(
ctx context.Context,
traceContext apm.TraceContext,
propagateLegacyHeader bool,
) context.Context {
traceparentValue := apmhttp.FormatTraceparentHeader(traceContext)
md, ok := metadata.FromOutgoingContext(ctx)
if !ok {
md = metadata.Pairs(w3cTraceparentHeader, traceparentValue)
} else {
md = md.Copy()
md.Set(w3cTraceparentHeader, traceparentValue)
}
if propagateLegacyHeader {
md.Set(elasticTraceparentHeader, traceparentValue)
}
if tracestate := traceContext.State.String(); tracestate != "" {
md.Set(tracestateHeader, tracestate)
}
return metadata.NewOutgoingContext(ctx, md)
}
func setSpanOutcome(span *apm.Span, err error) {
statusCode := statusCodeFromError(err)
// On the client side, all codes except for OK are treated as failures
// by default, and can be overridden by setting the Outcome explicitly.
if span.Outcome == "" {
switch statusCode {
case codes.OK:
span.Outcome = "success"
default:
span.Outcome = "failure"
}
}
}
type clientOptions struct {
tracer *apm.Tracer
}
// ClientOption sets options for client-side tracing.
type ClientOption func(*clientOptions)