Tailor, the library for tailing logs under logrotate
Tailor provides the functionality of tailing for e. g. nginx logs under logrotate. Tailor will follow a selected log file and reopen it if it's been rotated. Now, tailor doesn't require inotify, because it polls logs with a tiny delay. So the library can achieve cross-platform.
There is no plan to implement truncate detection.
Currently this library is used in production, handling 5k of opened files with a load over 100k rps per instance,
without such overhead.
Install
go get github.com/un000/tailorFeatures
- Tail files from any offsets
- Reopening on logrotate
- Rate limiter + support custom rate limiters
- Leaky bucket
- Performant helpers to trim or convert bytes to string
- Lag monitoring
Example
package main
import (
"context"
"fmt"
"io"
"time"
"github.com/un000/tailor"
)
func main() {
t := tailor.New(
"./github.com_access.log",
tailor.WithSeekOnStartup(0, io.SeekStart),
tailor.WithPollerTimeout(10*time.Millisecond),
)
ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
defer cancel()
err := t.Run(ctx)
if err != nil {
panic(err)
}
fmt.Println("Tailing file:", t.FileName())
for {
select {
case line, ok := <-t.Lines():
if !ok {
return
}
fmt.Println(line.StringTrimmed())
case err, ok := <-t.Errors():
if !ok {
return
}
panic(err)
}
}
}