115 lines
3.8 KiB
Go
115 lines
3.8 KiB
Go
// Copyright 2018 The Go Cloud Development Kit 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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// https://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 requestlog
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import (
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"bytes"
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"encoding/json"
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"io"
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"strconv"
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"sync"
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"time"
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)
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// A StackdriverLogger writes log entries in the Stackdriver forward JSON
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// format. The record's fields are suitable for consumption by
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// Stackdriver Logging.
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type StackdriverLogger struct {
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onErr func(error)
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mu sync.Mutex
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w io.Writer
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buf bytes.Buffer
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enc *json.Encoder
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}
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// NewStackdriverLogger returns a new logger that writes to w.
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// A nil onErr is treated the same as func(error) {}.
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func NewStackdriverLogger(w io.Writer, onErr func(error)) *StackdriverLogger {
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l := &StackdriverLogger{
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w: w,
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onErr: onErr,
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}
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l.enc = json.NewEncoder(&l.buf)
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return l
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}
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// Log writes a record to its writer. Multiple concurrent calls will
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// produce sequential writes to its writer.
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func (l *StackdriverLogger) Log(ent *Entry) {
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if err := l.log(ent); err != nil && l.onErr != nil {
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l.onErr(err)
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}
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}
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func (l *StackdriverLogger) log(ent *Entry) error {
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defer l.mu.Unlock()
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l.mu.Lock()
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l.buf.Reset()
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// r represents the fluent-plugin-google-cloud format
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// See https://github.com/GoogleCloudPlatform/fluent-plugin-google-cloud/blob/f93046d92f7722db2794a042c3f2dde5df91a90b/lib/fluent/plugin/out_google_cloud.rb#L145
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// to check json tags
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var r struct {
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HTTPRequest struct {
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RequestMethod string `json:"requestMethod"`
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RequestURL string `json:"requestUrl"`
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RequestSize int64 `json:"requestSize,string"`
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Status int `json:"status"`
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ResponseSize int64 `json:"responseSize,string"`
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UserAgent string `json:"userAgent"`
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RemoteIP string `json:"remoteIp"`
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Referer string `json:"referer"`
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Latency string `json:"latency"`
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} `json:"httpRequest"`
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Timestamp struct {
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Seconds int64 `json:"seconds"`
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Nanos int `json:"nanos"`
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} `json:"timestamp"`
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TraceID string `json:"logging.googleapis.com/trace"`
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SpanID string `json:"logging.googleapis.com/spanId"`
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}
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r.HTTPRequest.RequestMethod = ent.RequestMethod
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r.HTTPRequest.RequestURL = ent.RequestURL
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// TODO(light): determine whether this is the formula LogEntry expects.
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r.HTTPRequest.RequestSize = ent.RequestHeaderSize + ent.RequestBodySize
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r.HTTPRequest.Status = ent.Status
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// TODO(light): determine whether this is the formula LogEntry expects.
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r.HTTPRequest.ResponseSize = ent.ResponseHeaderSize + ent.ResponseBodySize
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r.HTTPRequest.UserAgent = ent.UserAgent
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r.HTTPRequest.RemoteIP = ent.RemoteIP
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r.HTTPRequest.Referer = ent.Referer
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r.HTTPRequest.Latency = string(appendLatency(nil, ent.Latency))
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t := ent.ReceivedTime.Add(ent.Latency)
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r.Timestamp.Seconds = t.Unix()
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r.Timestamp.Nanos = t.Nanosecond()
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r.TraceID = ent.TraceID.String()
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r.SpanID = ent.SpanID.String()
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if err := l.enc.Encode(r); err != nil {
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return err
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}
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_, err := l.w.Write(l.buf.Bytes())
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return err
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}
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func appendLatency(b []byte, d time.Duration) []byte {
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// Parses format understood by google-fluentd (which is looser than the documented LogEntry format).
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// See the comment at https://github.com/GoogleCloudPlatform/fluent-plugin-google-cloud/blob/e2f60cdd1d97e79ffe4e91bdbf6bd84837f27fa5/lib/fluent/plugin/out_google_cloud.rb#L1539
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b = strconv.AppendFloat(b, d.Seconds(), 'f', 9, 64)
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b = append(b, 's')
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return b
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}
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