Omitting client.Stop() prevents logs being pushed to loki server

[lfonosol]

Hello

I managed to get logs pushed to my loki grafana setup (with some trial and error) and I was wondering if it is necessary to call client.Stop() in order for the logs to be pushed to the loki server?

`func SetDefaultLogger() {
url := "http://localhost:3100/loki/api/v1/push"

config, lokiErr := loki.NewDefaultConfig(url)
if lokiErr != nil {
	panic(lokiErr)
}

client, lokiErr := loki.New(config)
if lokiErr != nil {
	panic(lokiErr)
}

// Is this necessary?
defer client.Stop()

option := slogloki.Option{Level: slog.LevelDebug, Client: client}
handler := option.NewLokiHandler()
logger := slog.New(handler).With(slog.String("job", "audit-log"))

slog.SetDefault(logger)

log.Print("log.Print")
logger.Debug("logger.Debug")
logger.Info("logger.Info")
logger.Warn("logger.Warn")
logger.Error("logger.Error")

}`

If I remove the line defer client.Stop() I don't see the messages in Grafana.

The problem for me is that my application will hang if the client is stopped and I try and call the default logger elsewhere in the code.

Is there a way I can set this default logger without having to call client.Stop()

[lfonosol]

I cloned the branch and created the following test

func TestNewLokiHandler_WhenDebugLevelNil_UsesDefaultLevel(t *testing.T) {

	config, _ := getDefaultConfig()
	client, _ := loki.New(config)

	option := Option{
		Level:  nil,
		Client: client,
	}
	handler := option.NewLokiHandler()

	// Omitting this causes leak
	client.Stop()
	assert.NotNil(t, handler)
}

func getDefaultConfig() (loki.Config, error) {
	return loki.NewDefaultConfig("http://localhost:3100/loki/api/v1/push")
}

When I omit the Client.Stop() line I get the following output:

goleak: Errors on successful test run: found unexpected goroutines:
[Goroutine 26 in state select, with github.com/grafana/loki-client-go/loki.(*Client).run on top of the stack:
goroutine 26 [select]:
github.com/grafana/loki-client-go/loki.(*Client).run(0xc00022f7c0)

Is this behaviour expected?

[samber]

If i remember well, the loki client put logs into a buffer and send a batch regularly.

Calling client.Stop() before program closes allows you to flush the buffer and perform a graceful stop.

If you remove this line, some logs might be dropped on exit.

[lfonosol]

at the moment none of the messages are being pushed. I wonder if my buffer is set too large somehow?

I will investigate this further and post updates here in case others run into similar problems.