logrusloki

Logrus Loki Hook

A simple non blocking logrus Hook pushing logs to a Loki server

Loki labels

The hook add every logrus field as label and the following default:

• app: the app name
• level: the log level, e.g. info

If log.ReportCaller is set:

• go_function: the go function name
• go_file: the go file name
• go_line: the go fine line number

Usage

If you are running on Grafana Cloud, use:

export LOKI_ADDR=https://logs-us-west1.grafana.net
export LOKI_USERNAME=<username>
export LOKI_PASSWORD=<password>

Create a new logrus Hook from env and log as usual:

package main

import (
	"time"

	"github.com/sirupsen/logrus"

	loki "gitlab.bertha.cloud/partitio/lab/logrus-loki-hook"
)

func main() {
	h, err := loki.NewHookFromEnv(
		"hook_example",
		logrus.TraceLevel,
		loki.WithFieldAsLabels(false),
		loki.WithLabelsKV("version", "v0.3.0"),
	)
	if err != nil {
		logrus.Fatal(err)
	}
	defer h.Close()
	log := logrus.New()
	log.SetLevel(logrus.TraceLevel)
	log.ReportCaller = true
	log.AddHook(h)
	i := 0
	for {
		i++
		l := log.WithField("value", i).WithField("test", true)
		if i%2 == 0 {
			l.Infof("it's the %d message", i)
		} else {
			l.Errorf("%d is even", i)
		}
		time.Sleep(time.Second)
	}
}

Loki Command Line example query:

logcli query '{app="hook_example", version="0.3.0"}'

2020-11-09T18:40:39+01:00 {app="hook_example", version="0.3.0"} time="2020-11-09T18:40:39+01:00" level=error msg="1 is even" func=main.main file="/logrus-loki-hook/example/example.go:28" test=true value=1
2020-11-09T18:40:40+01:00 {app="hook_example", version="0.3.0"} time="2020-11-09T18:40:40+01:00" level=info msg="it's the 2 message" func=main.main file="/logrus-loki-hook/example/example.go:26" test=true value=2
2020-11-09T18:40:41+01:00 {app="hook_example", version="0.3.0"} time="2020-11-09T18:40:41+01:00" level=error msg="3 is even" func=main.main file="/logrus-loki-hook/example/example.go:28" test=true value=3
2020-11-09T18:40:42+01:00 {app="hook_example", version="0.3.0"} time="2020-11-09T18:40:42+01:00" level=info msg="it's the 4 message" func=main.main file="/logrus-loki-hook/example/example.go:26" test=true value=4
2020-11-09T18:40:43+01:00 {app="hook_example", version="0.3.0"} time="2020-11-09T18:40:43+01:00" level=error msg="5 is even" func=main.main file="/logrus-loki-hook/example/example.go:28" test=true value=5
2020-11-09T18:40:44+01:00 {app="hook_example", version="0.3.0"} time="2020-11-09T18:40:44+01:00" level=info msg="it's the 6 message" func=main.main file="/logrus-loki-hook/example/example.go:26" test=true value=6
2020-11-09T18:40:45+01:00 {app="hook_example", version="0.3.0"} time="2020-11-09T18:40:45+01:00" level=error msg="7 is even" func=main.main file="/logrus-loki-hook/example/example.go:28" test=true value=7
2020-11-09T18:40:46+01:00 {app="hook_example", version="0.3.0"} time="2020-11-09T18:40:46+01:00" level=info msg="it's the 8 message" func=main.main file="/logrus-loki-hook/example/example.go:26" test=true value=8
2020-11-09T18:40:47+01:00 {app="hook_example", version="0.3.0"} time="2020-11-09T18:40:47+01:00" level=error msg="9 is even" func=main.main file="/logrus-loki-hook/example/example.go:28" test=true value=9
2020-11-09T18:40:48+01:00 {app="hook_example", version="0.3.0"} time="2020-11-09T18:40:48+01:00" level=info msg="it's the 10 message" func=main.main file="/logrus-loki-hook/example/example.go:26" test=true value=10
2020-11-09T18:40:49+01:00 {app="hook_example", version="0.3.0"} time="2020-11-09T18:40:49+01:00" level=error msg="11 is even" func=main.main file="/logrus-loki-hook/example/example.go:28" test=true value=11