README.md

cslog

A simple wrapper to put the logger in a context, so that you can simply pass the context around. Examples include attaching relevant information contextually to an HTTP request, such that information is preserved downstream, without having to also pass around a logger. You're probably going to pass the context anyway.

Example

import (
	"context"
	"log/slog"
	"os"
	"time"

    	"github.com/jclasley/cslog"
)

func main() {
	var opt *slog.HandlerOptions
	// uncomment below to have the debug show up!
	// opt = &slog.HandlerOptions{Level: slog.LevelDebug}

	ctx := cslog.FromBackground(slog.New(slog.NewJSONHandler(os.Stdout, cslog.WithoutTime(opt))))

	cslog.Info(ctx, "hello!") // {"level":"INFO","msg":"hello!"}
	y, _, _ := time.Now().Local().Date()
	ctx = cslog.WithAttrs(ctx, slog.Int("year", y))

	got := getFromDB(cslog.WithGroup(ctx, "getFromDB"), "1234567890")
	if want := 43; got != want {
		cslog.Error(ctx, "wrong result!", slog.Int("wanted", want), slog.Int("got", got))
        	// {"level":"ERROR","msg":"wrong result!","year":2023,"wanted":43,"got":42} 
	}
}

func getFromDB(ctx context.Context, userID string) int {
    	ctx, cancel := context.WithTimeout(ctx, 3*time.Second)
    	defer cancel()

    	ctx = cslog.WithAttrs(ctx, slog.String("userID", userID))

    	// call DB
    	const fakeResult = 42
    	cslog.Debug(ctx, "got from DB", slog.Int("result", 42))
        // {"level":"DEBUG","msg":"got from DB","year":2023,"getFromDB":{"userID":"foobar!!!","result":42}}
    	return fakeResult
}

Option funcs

The ReplaceAttr function used by slog is awesome, and I can forsee adding more option functions in the future. For now, I've only implemented what I've found to be the most useful, which is to drop time from the attributes.

You can check out the tests to see a nifty one I created that hides secret values. Basically, if you have some group secret, all attribute values added to that will be replaced with as many * as the value has. So slog.Group("secret", slog.Group("db", slog.String("password", "12345"))) will result in an attribute (assuming a JSON handler) that looks like "secret":{"db":{"password":"*****"}}. You could probably also configure this so secrets are shown at the DEBUG level, and so on. Pretty cool.