A versatile logger configurable via environment variables. It was first built for peer-calls, an open-source, distributed peer to peer conferencing software, but I found it useful in a lot of other projects so I'm importing it here.

package main

import (
	"errors"

	"github.com/peer-calls/log"
)

func main() {
	cfg := log.NewConfig(log.ConfigMap{
		"test1": log.LevelWarn,
		"test2": log.LevelInfo,
	})

	factory := log.New().WithConfig(cfg)

	logCtx := log.Ctx{
		"a": "1000",
		"b": 20,
	}

	l1 := factory.WithNamespace("test1")
	l2 := factory.WithNamespace("test2")

	l1.Info("test", logCtx)
	l2.Warn("test", logCtx)
	l2.Error("test", errors.New("err1"), logCtx)

	l2.Info("test", logCtx)
	l2.Warn("test", logCtx)
	l2.Error("test", errors.New("err2"), logCtx)
}

After running the script above you should see the output below:

$ go run ./main.go
2022-01-27T09:38:46.952896+01:00  warn [               test2] test a=1000 b=20
2022-01-27T09:38:46.953052+01:00 error [               test2] test: err1 a=1000 b=20
2022-01-27T09:38:46.953068+01:00  info [               test2] test a=1000 b=20
2022-01-27T09:38:46.953080+01:00  warn [               test2] test a=1000 b=20
2022-01-27T09:38:46.953093+01:00 error [               test2] test: err2 a=1000 b=20

This is only the default logging format. It is configurable. For more details see the docs: https://pkg.go.dev/github.com/peer-calls.

If you're using .golangci-lint.yml and don't want to handle write errors, you should add this to your linter settings:

linters-settings:
  errcheck:
    exclude: .golangci-errcheck-exclude.txt

And then to .golangci-errcheck-exclude.txt:

(github.com/peer-calls/peer-calls/log.Logger).Error
(github.com/peer-calls/peer-calls/log.Logger).Warn
(github.com/peer-calls/peer-calls/log.Logger).Info
(github.com/peer-calls/peer-calls/log.Logger).Debug
(github.com/peer-calls/peer-calls/log.Logger).Trace

Apache v2