package logger import ( "fmt" "io" "os" "path" "path/filepath" "sync" "github.com/mattn/go-colorable" "github.com/rs/zerolog" fallbacklog "github.com/rs/zerolog/log" "github.com/urfave/cli/v2" "golang.org/x/term" "gopkg.in/natefinch/lumberjack.v2" ) const ( EnableTerminalLog = false DisableTerminalLog = true LogLevelFlag = "loglevel" LogFileFlag = "logfile" LogDirectoryFlag = "log-directory" LogTransportLevelFlag = "transport-loglevel" LogSSHDirectoryFlag = "log-directory" LogSSHLevelFlag = "log-level" dirPermMode = 0744 // rwxr--r-- filePermMode = 0644 // rw-r--r-- ) func fallbackLogger(err error) *zerolog.Logger { failLog := fallbacklog.With().Logger() fallbacklog.Error().Msgf("Falling back to a default logger due to logger setup failure: %s", err) return &failLog } type resilientMultiWriter struct { writers []io.Writer } // This custom resilientMultiWriter is an alternative to zerolog's so that we can make it resilient to individual // writer's errors. E.g., when running as a Windows service, the console writer fails, but we don't want to // allow that to prevent all logging to fail due to breaking the for loop upon an error. func (t resilientMultiWriter) Write(p []byte) (n int, err error) { for _, w := range t.writers { _, _ = w.Write(p) } return len(p), nil } func newZerolog(loggerConfig *Config) *zerolog.Logger { var writers []io.Writer if loggerConfig.ConsoleConfig != nil { writers = append(writers, createConsoleLogger(*loggerConfig.ConsoleConfig)) } if loggerConfig.FileConfig != nil { fileLogger, err := createFileWriter(*loggerConfig.FileConfig) if err != nil { return fallbackLogger(err) } writers = append(writers, fileLogger) } if loggerConfig.RollingConfig != nil { rollingLogger, err := createRollingLogger(*loggerConfig.RollingConfig) if err != nil { return fallbackLogger(err) } writers = append(writers, rollingLogger) } multi := resilientMultiWriter{writers} level, err := zerolog.ParseLevel(loggerConfig.MinLevel) if err != nil { return fallbackLogger(err) } log := zerolog.New(multi).With().Timestamp().Logger().Level(level) return &log } func CreateTransportLoggerFromContext(c *cli.Context, disableTerminal bool) *zerolog.Logger { return createFromContext(c, LogTransportLevelFlag, LogDirectoryFlag, disableTerminal) } func CreateLoggerFromContext(c *cli.Context, disableTerminal bool) *zerolog.Logger { return createFromContext(c, LogLevelFlag, LogDirectoryFlag, disableTerminal) } func CreateSSHLoggerFromContext(c *cli.Context, disableTerminal bool) *zerolog.Logger { return createFromContext(c, LogSSHLevelFlag, LogSSHDirectoryFlag, disableTerminal) } func createFromContext( c *cli.Context, logLevelFlagName, logDirectoryFlagName string, disableTerminal bool, ) *zerolog.Logger { logLevel := c.String(logLevelFlagName) logFile := c.String(LogFileFlag) logDirectory := c.String(logDirectoryFlagName) loggerConfig := CreateConfig( logLevel, disableTerminal, logDirectory, logFile, ) log := newZerolog(loggerConfig) if incompatibleFlagsSet := logFile != "" && logDirectory != ""; incompatibleFlagsSet { log.Error().Msgf("Your config includes values for both %s and %s, but they are incompatible. %s takes precedence.", LogFileFlag, logDirectoryFlagName, LogFileFlag) } return log } func Create(loggerConfig *Config) *zerolog.Logger { if loggerConfig == nil { loggerConfig = &Config{ defaultConfig.ConsoleConfig, nil, nil, defaultConfig.MinLevel, } } return newZerolog(loggerConfig) } func createConsoleLogger(config ConsoleConfig) io.Writer { consoleOut := os.Stderr return zerolog.ConsoleWriter{ Out: colorable.NewColorable(consoleOut), NoColor: config.noColor || !term.IsTerminal(int(consoleOut.Fd())), } } type fileInitializer struct { once sync.Once writer io.Writer creationError error } var ( singleFileInit fileInitializer rotatingFileInit fileInitializer ) func createFileWriter(config FileConfig) (io.Writer, error) { singleFileInit.once.Do(func() { var logFile io.Writer fullpath := config.Fullpath() // Try to open the existing file logFile, err := os.OpenFile(fullpath, os.O_APPEND|os.O_WRONLY, filePermMode) if err != nil { // If the existing file wasn't found, or couldn't be opened, just ignore // it and recreate a new one. logFile, err = createDirFile(config) // If creating a new logfile fails, then we have no choice but to error out. if err != nil { singleFileInit.creationError = err return } } singleFileInit.writer = logFile }) return singleFileInit.writer, singleFileInit.creationError } func createDirFile(config FileConfig) (io.Writer, error) { if config.Dirname != "" { err := os.MkdirAll(config.Dirname, dirPermMode) if err != nil { return nil, fmt.Errorf("unable to create directories for new logfile: %s", err) } } mode := os.FileMode(filePermMode) fullPath := filepath.Join(config.Dirname, config.Filename) logFile, err := os.OpenFile(fullPath, os.O_CREATE|os.O_WRONLY|os.O_APPEND, mode) if err != nil { return nil, fmt.Errorf("unable to create a new logfile: %s", err) } return logFile, nil } func createRollingLogger(config RollingConfig) (io.Writer, error) { rotatingFileInit.once.Do(func() { if err := os.MkdirAll(config.Dirname, dirPermMode); err != nil { rotatingFileInit.creationError = err return } rotatingFileInit.writer = &lumberjack.Logger{ Filename: path.Join(config.Dirname, config.Filename), MaxBackups: config.maxBackups, MaxSize: config.maxSize, MaxAge: config.maxAge, } }) return rotatingFileInit.writer, rotatingFileInit.creationError }