log.go•5.25 kB
// Copyright 2024 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
//
// http://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 log
import (
"context"
"fmt"
"io"
"log/slog"
"strings"
)
// StdLogger is the standard logger
type StdLogger struct {
outLogger *slog.Logger
errLogger *slog.Logger
}
// NewStdLogger create a Logger that uses out and err for informational and error messages.
func NewStdLogger(outW, errW io.Writer, logLevel string) (Logger, error) {
//Set log level
var programLevel = new(slog.LevelVar)
slogLevel, err := SeverityToLevel(logLevel)
if err != nil {
return nil, err
}
programLevel.Set(slogLevel)
handlerOptions := &slog.HandlerOptions{Level: programLevel}
return &StdLogger{
outLogger: slog.New(NewValueTextHandler(outW, handlerOptions)),
errLogger: slog.New(NewValueTextHandler(errW, handlerOptions)),
}, nil
}
// DebugContext logs debug messages
func (sl *StdLogger) DebugContext(ctx context.Context, msg string, keysAndValues ...interface{}) {
sl.outLogger.DebugContext(ctx, msg, keysAndValues...)
}
// InfoContext logs debug messages
func (sl *StdLogger) InfoContext(ctx context.Context, msg string, keysAndValues ...interface{}) {
sl.outLogger.InfoContext(ctx, msg, keysAndValues...)
}
// WarnContext logs warning messages
func (sl *StdLogger) WarnContext(ctx context.Context, msg string, keysAndValues ...interface{}) {
sl.errLogger.WarnContext(ctx, msg, keysAndValues...)
}
// ErrorContext logs error messages
func (sl *StdLogger) ErrorContext(ctx context.Context, msg string, keysAndValues ...interface{}) {
sl.errLogger.ErrorContext(ctx, msg, keysAndValues...)
}
const (
Debug = "DEBUG"
Info = "INFO"
Warn = "WARN"
Error = "ERROR"
)
// Returns severity level based on string.
func SeverityToLevel(s string) (slog.Level, error) {
switch strings.ToUpper(s) {
case Debug:
return slog.LevelDebug, nil
case Info:
return slog.LevelInfo, nil
case Warn:
return slog.LevelWarn, nil
case Error:
return slog.LevelError, nil
default:
return slog.Level(-5), fmt.Errorf("invalid log level")
}
}
// Returns severity string based on level.
func levelToSeverity(s string) (string, error) {
switch s {
case slog.LevelDebug.String():
return Debug, nil
case slog.LevelInfo.String():
return Info, nil
case slog.LevelWarn.String():
return Warn, nil
case slog.LevelError.String():
return Error, nil
default:
return "", fmt.Errorf("invalid slog level")
}
}
type StructuredLogger struct {
outLogger *slog.Logger
errLogger *slog.Logger
}
// NewStructuredLogger create a Logger that logs messages using JSON.
func NewStructuredLogger(outW, errW io.Writer, logLevel string) (Logger, error) {
//Set log level
var programLevel = new(slog.LevelVar)
slogLevel, err := SeverityToLevel(logLevel)
if err != nil {
return nil, err
}
programLevel.Set(slogLevel)
replace := func(groups []string, a slog.Attr) slog.Attr {
switch a.Key {
case slog.LevelKey:
value := a.Value.String()
sev, _ := levelToSeverity(value)
return slog.Attr{
Key: "severity",
Value: slog.StringValue(sev),
}
case slog.MessageKey:
return slog.Attr{
Key: "message",
Value: a.Value,
}
case slog.SourceKey:
return slog.Attr{
Key: "logging.googleapis.com/sourceLocation",
Value: a.Value,
}
case slog.TimeKey:
return slog.Attr{
Key: "timestamp",
Value: a.Value,
}
}
return a
}
// Configure structured logs to adhere to Cloud LogEntry format
// https://cloud.google.com/logging/docs/reference/v2/rest/v2/LogEntry
outHandler := handlerWithSpanContext(slog.NewJSONHandler(outW, &slog.HandlerOptions{
AddSource: true,
Level: programLevel,
ReplaceAttr: replace,
}))
errHandler := handlerWithSpanContext(slog.NewJSONHandler(errW, &slog.HandlerOptions{
AddSource: true,
Level: programLevel,
ReplaceAttr: replace,
}))
return &StructuredLogger{outLogger: slog.New(outHandler), errLogger: slog.New(errHandler)}, nil
}
// DebugContext logs debug messages
func (sl *StructuredLogger) DebugContext(ctx context.Context, msg string, keysAndValues ...interface{}) {
sl.outLogger.DebugContext(ctx, msg, keysAndValues...)
}
// InfoContext logs info messages
func (sl *StructuredLogger) InfoContext(ctx context.Context, msg string, keysAndValues ...interface{}) {
sl.outLogger.InfoContext(ctx, msg, keysAndValues...)
}
// WarnContext logs warning messages
func (sl *StructuredLogger) WarnContext(ctx context.Context, msg string, keysAndValues ...interface{}) {
sl.errLogger.WarnContext(ctx, msg, keysAndValues...)
}
// ErrorContext logs error messages
func (sl *StructuredLogger) ErrorContext(ctx context.Context, msg string, keysAndValues ...interface{}) {
sl.errLogger.ErrorContext(ctx, msg, keysAndValues...)
}