tvl-depot/tools/nixery/server/logs.go

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// Copyright 2019 Google LLC
//
// Licensed 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
//
// https://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 main
// This file configures different log formatters via logrus. The
// standard formatter uses a structured JSON format that is compatible
// with Stackdriver Error Reporting.
//
// https://cloud.google.com/error-reporting/docs/formatting-error-messages
import (
"bytes"
"encoding/json"
log "github.com/sirupsen/logrus"
)
type stackdriverFormatter struct{}
type serviceContext struct {
Service string `json:"service"`
Version string `json:"version"`
}
type reportLocation struct {
FilePath string `json:"filePath"`
LineNumber int `json:"lineNumber"`
FunctionName string `json:"functionName"`
}
var nixeryContext = serviceContext{
Service: "nixery",
}
// isError determines whether an entry should be logged as an error
// (i.e. with attached `context`).
//
// This requires the caller information to be present on the log
// entry, as stacktraces are not available currently.
func isError(e *log.Entry) bool {
l := e.Level
return (l == log.ErrorLevel || l == log.FatalLevel || l == log.PanicLevel) &&
e.HasCaller()
}
// logSeverity formats the entry's severity into a format compatible
// with Stackdriver Logging.
//
// The two formats that are being mapped do not have an equivalent set
// of severities/levels, so the mapping is somewhat arbitrary for a
// handful of them.
//
// https://cloud.google.com/logging/docs/reference/v2/rest/v2/LogEntry#LogSeverity
func logSeverity(l log.Level) string {
switch l {
case log.TraceLevel:
return "DEBUG"
case log.DebugLevel:
return "DEBUG"
case log.InfoLevel:
return "INFO"
case log.WarnLevel:
return "WARNING"
case log.ErrorLevel:
return "ERROR"
case log.FatalLevel:
return "CRITICAL"
case log.PanicLevel:
return "EMERGENCY"
default:
return "DEFAULT"
}
}
func (f stackdriverFormatter) Format(e *log.Entry) ([]byte, error) {
msg := e.Data
msg["serviceContext"] = &nixeryContext
msg["message"] = &e.Message
msg["eventTime"] = &e.Time
msg["severity"] = logSeverity(e.Level)
if e, ok := msg[log.ErrorKey]; ok {
if err, isError := e.(error); isError {
msg[log.ErrorKey] = err.Error()
} else {
delete(msg, log.ErrorKey)
}
}
if isError(e) {
loc := reportLocation{
FilePath: e.Caller.File,
LineNumber: e.Caller.Line,
FunctionName: e.Caller.Function,
}
msg["context"] = &loc
}
b := new(bytes.Buffer)
err := json.NewEncoder(b).Encode(&msg)
return b.Bytes(), err
}
func init() {
nixeryContext.Version = version
log.SetReportCaller(true)
log.SetFormatter(stackdriverFormatter{})
}