open-consul/logging/logger.go

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// Copyright (c) HashiCorp, Inc.
// SPDX-License-Identifier: MPL-2.0
package logging
import (
"fmt"
"io"
"path/filepath"
"time"
"github.com/hashicorp/go-hclog"
gsyslog "github.com/hashicorp/go-syslog"
)
// Config is used to set up logging.
type Config struct {
// LogLevel is the minimum level to be logged.
LogLevel string
// LogJSON controls outputing logs in a JSON format.
LogJSON bool
// Name is the name the returned logger will use to prefix log lines.
Name string
// EnableSyslog controls forwarding to syslog.
EnableSyslog bool
// SyslogFacility is the destination for syslog forwarding.
SyslogFacility string
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// LogFilePath is the path to write the logs to the user specified file.
LogFilePath string
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// LogRotateDuration is the user specified time to rotate logs
LogRotateDuration time.Duration
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// LogRotateBytes is the user specified byte limit to rotate logs
LogRotateBytes int
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// LogRotateMaxFiles is the maximum number of past archived log files to keep
LogRotateMaxFiles int
}
// defaultRotateDuration is the default time taken by the agent to rotate logs
const defaultRotateDuration = 24 * time.Hour
type LogSetupErrorFn func(string)
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// noErrorWriter is a wrapper to suppress errors when writing to w.
type noErrorWriter struct {
w io.Writer
}
func (w noErrorWriter) Write(p []byte) (n int, err error) {
_, _ = w.w.Write(p)
// We purposely return n == len(p) as if write was successful
return len(p), nil
}
// Setup logging from Config, and return an hclog Logger.
//
// Logs may be written to out, and optionally to syslog, and a file.
func Setup(config Config, out io.Writer) (hclog.InterceptLogger, error) {
if !ValidateLogLevel(config.LogLevel) {
return nil, fmt.Errorf("Invalid log level: %s. Valid log levels are: %v",
config.LogLevel,
allowedLogLevels)
}
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// If out is os.Stdout and Consul is being run as a Windows Service, writes will
// fail silently, which may inadvertently prevent writes to other writers.
// noErrorWriter is used as a wrapper to suppress any errors when writing to out.
writers := []io.Writer{noErrorWriter{w: out}}
if config.EnableSyslog {
retries := 12
delay := 5 * time.Second
for i := 0; i <= retries; i++ {
syslog, err := gsyslog.NewLogger(gsyslog.LOG_NOTICE, config.SyslogFacility, "consul")
if err == nil {
writers = append(writers, &SyslogWrapper{l: syslog})
break
}
if i == retries {
timeout := time.Duration(retries) * delay
return nil, fmt.Errorf("Syslog setup did not succeed within timeout (%s).", timeout.String())
}
time.Sleep(delay)
}
}
// Create a file logger if the user has specified the path to the log file
if config.LogFilePath != "" {
dir, fileName := filepath.Split(config.LogFilePath)
if fileName == "" {
fileName = "consul.log"
}
if config.LogRotateDuration == 0 {
config.LogRotateDuration = defaultRotateDuration
}
logFile := &LogFile{
fileName: fileName,
logPath: dir,
duration: config.LogRotateDuration,
MaxBytes: config.LogRotateBytes,
MaxFiles: config.LogRotateMaxFiles,
}
if err := logFile.pruneFiles(); err != nil {
return nil, fmt.Errorf("Failed to prune log files: %w", err)
}
if err := logFile.openNew(); err != nil {
return nil, fmt.Errorf("Failed to setup logging: %w", err)
}
writers = append(writers, logFile)
}
logger := hclog.NewInterceptLogger(&hclog.LoggerOptions{
Level: LevelFromString(config.LogLevel),
Name: config.Name,
Output: io.MultiWriter(writers...),
JSONFormat: config.LogJSON,
})
return logger, nil
}