log

Documentation

Overview

Package log implements a simple logging handler.

Index

• Constants
• func GetId(ctx context.Context) (string, bool)
• func New(w io.Writer, maxMsgs int) func(ctx context.Context) *slog.Logger
• type Handler
  • func (h Handler) Enabled(_ context.Context, _ slog.Level) bool
  • func (h Handler) Handle(r slog.Record) error
  • func (h Handler) StdLogger() *stdLog.Logger
  • func (h Handler) WithAttrs(attrs []slog.Attr) slog.Handler
  • func (h Handler) WithGroup(name string) slog.Handler
  • func (h Handler) Write(p []byte) (n int, err error)

Examples

• New

Constants

const CtxKey = logContextKeyType("Ong-logID")

CtxKey is the name of the context key used to store the logID.

Functions

func GetId

func GetId(ctx context.Context) (string, bool)

GetId gets a logId either from the provided context or auto-generated. It returns the logID and true if the id came from ctx else false

func New

func New(w io.Writer, maxMsgs int) func(ctx context.Context) *slog.Logger

New returns a function that returns an slog.Logger The logger is backed by a handler that stores log messages into a circular buffer. Those log messages are only flushed to the underlying io.Writer when a message with level >= slog.LevelError is logged. A unique logID is also added to the logs that acts as a correlation id of log events from diffrent components that neverthless are related.

Example

package main

import (
	"context"
	"errors"
	"os"

	"github.com/komuw/ong/log"
)

func main() {
	l := log.New(os.Stdout, 1000)

	hey := func(ctx context.Context) {
		logger := l(ctx)

		logger.Info("sending email", "email", "jane@example.com")
		logger.Error("fail", errors.New("sending email failed."), "email", "jane@example.com")
	}

	hey(context.Background())

	// example output:
	//   {"time":"2023-02-03T11:26:47.460792396Z","level":"INFO","source":"main.go:17","msg":"sending email","email":"jane@example.com","logID":"DQTXGs3HM8Xgx3yt"}
	//   {"time":"2023-02-03T11:26:47.46080217Z","level":"ERROR","source":"main.go:18","msg":"fail","err":"sending email failed.","email":"jane@example.com","logID":"DQTXGs3HM8Xgx3yt"}
}

Types

type Handler

type Handler struct {
	// contains filtered or unexported fields
}

Handler is an slog.Handler It stores log messages into a circular buffer. Those log messages are only flushed to the underlying io.Writer when a message with level >= slog.LevelError is logged.

func (Handler) Enabled

func (h Handler) Enabled(_ context.Context, _ slog.Level) bool

func (Handler) Handle

func (h Handler) Handle(r slog.Record) error

func (Handler) StdLogger

func (h Handler) StdLogger() *stdLog.Logger

StdLogger returns an unstructured logger from the Go standard library log package. That logger will use l as its output.

func (Handler) WithAttrs

func (h Handler) WithAttrs(attrs []slog.Attr) slog.Handler

func (Handler) WithGroup

func (h Handler) WithGroup(name string) slog.Handler

func (Handler) Write

func (h Handler) Write(p []byte) (n int, err error)

Write implements the io.Writer interface. This is useful if you want to set this logger as a writer for the standard library log.