package context import ( "fmt" "github.com/docker/distribution/uuid" "github.com/Sirupsen/logrus" ) // Logger provides a leveled-logging interface. type Logger interface { // standard logger methods Print(args ...interface{}) Printf(format string, args ...interface{}) Println(args ...interface{}) Fatal(args ...interface{}) Fatalf(format string, args ...interface{}) Fatalln(args ...interface{}) Panic(args ...interface{}) Panicf(format string, args ...interface{}) Panicln(args ...interface{}) // Leveled methods, from logrus Debug(args ...interface{}) Debugf(format string, args ...interface{}) Debugln(args ...interface{}) Error(args ...interface{}) Errorf(format string, args ...interface{}) Errorln(args ...interface{}) Info(args ...interface{}) Infof(format string, args ...interface{}) Infoln(args ...interface{}) Warn(args ...interface{}) Warnf(format string, args ...interface{}) Warnln(args ...interface{}) } // WithLogger creates a new context with provided logger. func WithLogger(ctx Context, logger Logger) Context { return WithValue(ctx, "logger", logger) } // GetLoggerWithField returns a logger instance with the specified field key // and value without affecting the context. Extra specified keys will be // resolved from the context. func GetLoggerWithField(ctx Context, key, value interface{}, keys ...interface{}) Logger { return getLogrusLogger(ctx, keys...).WithField(fmt.Sprint(key), value) } // GetLoggerWithFields returns a logger instance with the specified fields // without affecting the context. Extra specified keys will be resolved from // the context. func GetLoggerWithFields(ctx Context, fields map[string]interface{}, keys ...interface{}) Logger { return getLogrusLogger(ctx, keys...).WithFields(logrus.Fields(fields)) } // GetLogger returns the logger from the current context, if present. If one // or more keys are provided, they will be resolved on the context and // included in the logger. While context.Value takes an interface, any key // argument passed to GetLogger will be passed to fmt.Sprint when expanded as // a logging key field. If context keys are integer constants, for example, // its recommended that a String method is implemented. func GetLogger(ctx Context, keys ...interface{}) Logger { return getLogrusLogger(ctx, keys...) } // GetLogrusLogger returns the logrus logger for the context. If one more keys // are provided, they will be resolved on the context and included in the // logger. Only use this function if specific logrus functionality is // required. func getLogrusLogger(ctx Context, keys ...interface{}) *logrus.Entry { var logger *logrus.Entry // Get a logger, if it is present. loggerInterface := ctx.Value("logger") if loggerInterface != nil { if lgr, ok := loggerInterface.(*logrus.Entry); ok { logger = lgr } } if logger == nil { // If no logger is found, just return the standard logger. logger = logrus.NewEntry(logrus.StandardLogger()) } fields := logrus.Fields{} for _, key := range keys { v := ctx.Value(key) if v != nil { fields[fmt.Sprint(key)] = v } } return logger.WithFields(fields) } func init() { // inject a logger into the uuid library. uuid.Loggerf = GetLogger(Background()).Warnf }