mirror of
https://github.com/open-telemetry/opentelemetry-go.git
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102 lines
2.5 KiB
Go
102 lines
2.5 KiB
Go
// Copyright 2019, OpenTelemetry Authors
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package httptrace
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import (
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"encoding/binary"
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"net/http"
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"github.com/lightstep/tracecontext.go"
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"github.com/lightstep/tracecontext.go/tracestate"
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"go.opentelemetry.io/api/core"
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"go.opentelemetry.io/api/key"
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"go.opentelemetry.io/api/tag"
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)
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const (
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Vendor = "ot"
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)
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var (
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HostKey = key.New("http.host")
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URLKey = key.New("http.url")
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encoding = binary.BigEndian
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)
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// Returns the Attributes, Context Tags, and SpanContext that were encoded by Inject.
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func Extract(req *http.Request) ([]core.KeyValue, []core.KeyValue, core.SpanContext) {
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tc, err := tracecontext.FromHeaders(req.Header)
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if err != nil {
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return nil, nil, core.SpanContext{}
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}
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var sc core.SpanContext
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sc.SpanID = encoding.Uint64(tc.TraceParent.SpanID[0:8])
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sc.TraceID.High = encoding.Uint64(tc.TraceParent.TraceID[0:8])
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sc.TraceID.Low = encoding.Uint64(tc.TraceParent.TraceID[8:16])
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attrs := []core.KeyValue{
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URLKey.String(req.URL.String()),
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// Etc.
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}
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var tags []core.KeyValue
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for _, ts := range tc.TraceState {
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if ts.Vendor != Vendor {
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continue
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}
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// TODO: max-hops, type conversion questions answered,
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// case-conversion questions.
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tags = append(tags, key.New(ts.Tenant).String(ts.Value))
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}
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return attrs, tags, sc
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}
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type hinjector struct {
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*http.Request
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}
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func (h hinjector) Inject(sc core.SpanContext, tags tag.Map) {
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var tc tracecontext.TraceContext
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var sid [8]byte
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var tid [16]byte
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encoding.PutUint64(sid[0:8], sc.SpanID)
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encoding.PutUint64(tid[0:8], sc.TraceID.High)
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encoding.PutUint64(tid[8:16], sc.TraceID.Low)
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tc.TraceParent.Version = tracecontext.Version
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tc.TraceParent.TraceID = tid
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tc.TraceParent.SpanID = sid
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tc.TraceParent.Flags.Recorded = true // Note: not implemented.
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tags.Foreach(func(kv core.KeyValue) bool {
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// TODO: implement MaxHops
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tc.TraceState = append(tc.TraceState, tracestate.Member{
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Vendor: Vendor,
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Tenant: kv.Key.Variable.Name,
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Value: kv.Value.Emit(),
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})
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return true
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})
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tc.SetHeaders(h.Header)
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}
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