Graylog Hook for Logrus 
Use this hook to send your logs to Graylog server over UDP. The hook is non-blocking: even if UDP is used to send messages, the extra work should not block the logging function.
All logrus fields will be sent as additional fields on Graylog.
The hook must be configured with:
- A Graylog GELF UDP address (a "ip:port" string).
- an optional hash with extra global fields. These fields will be included in all messages sent to Graylog
package main
import (
log "github.com/sirupsen/logrus"
"github.com/gemnasium/logrus-graylog-hook/v3"
)
func main() {
hook := graylog.NewGraylogHook("<graylog_ip>:<graylog_port>", map[string]interface{}{"this": "is logged every time"})
log.AddHook(hook)
log.Info("some logging message")
}package main
import (
log "github.com/sirupsen/logrus"
"github.com/gemnasium/logrus-graylog-hook/v3"
)
func main() {
hook := graylog.NewAsyncGraylogHook("<graylog_ip>:<graylog_port>", map[string]interface{}{"this": "is logged every time"})
// NOTE: you must call Flush() before your program exits to ensure ALL of your logs are sent.
// This defer statement will not have that effect if you write it in a non-main() method.
defer hook.Flush()
log.AddHook(hook)
log.Info("some logging message")
}For some reason, you may want to disable logging on stdout, and keep only the messages in Graylog (ie: a webserver inside a docker container).
You can redirect stdout to /dev/null, or just not log anything by creating a NullFormatter implementing logrus.Formatter interface:
type NullFormatter struct {
}
// Don't spend time formatting logs
func (NullFormatter) Format(e *log.Entry) ([]byte, error) {
return []byte{}, nil
}And set this formatter as the new logging formatter:
log.Infof("Log messages are now sent to Graylog (udp://%s)", graylogAddr) // Give a hint why logs are empty
log.AddHook(graylog.NewGraylogHook(graylogAddr, "api", map[string]interface{}{})) // set graylogAddr accordingly
log.SetFormatter(new(NullFormatter)) // Don't send logs to stdout