Provide an io.Writer that periodically rotates log files from within the application. Port of File::RotateLogs from Perl to Go.
Fork from repository file-rotatelogs.
import (
"log"
"net/http"
apachelog "github.com/lestrrat-go/apache-logformat"
rotatelogs "github.com/derekhjray/rotatelogs"
)
func main() {
mux := http.NewServeMux()
mux.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) { ... })
logf, err := rotatelogs.New(
"/path/to/access_log.%Y%m%d%H%M",
rotatelogs.WithLinkName("/path/to/access_log"),
rotatelogs.WithMaxAge(24 * time.Hour),
rotatelogs.WithRotationTime(time.Hour),
)
if err != nil {
log.Printf("failed to create rotatelogs: %s", err)
return
}
// Now you must write to logf. apache-logformat library can create
// a http.Handler that only writes the approriate logs for the request
// to the given handle
http.ListenAndServe(":8080", apachelog.CombinedLog.Wrap(mux, logf))
}When you integrate this to into your app, it automatically write to logs that are rotated from within the app: No more disk-full alerts because you forgot to setup logrotate!
To install, simply issue a go get:
go get github.com/derekhjray/rotatelogs
It's normally expected that this library is used with some other
logging service, such as the built-in log library, or loggers
such as github.com/lestrrat-go/apache-logformat.
import(
"log"
"github.com/derekhjray/rotatelogs"
)
func main() {
rl, _ := rotatelogs.New("/path/to/access_log.%Y%m%d%H%M")
log.SetOutput(rl)
/* elsewhere ... */
log.Printf("Hello, World!")
}The pattern used to generate actual log file names. You should use patterns using the strftime (3) format. For example:
rotatelogs.New("/var/log/myapp/log.%Y%m%d")You may specify an object that implements the roatatelogs.Clock interface. When this option is supplied, it's used to determine the current time to base all of the calculations on. For example, if you want to base your calculations in UTC, you may specify rotatelogs.UTC
rotatelogs.New(
"/var/log/myapp/log.%Y%m%d",
rotatelogs.WithClock(rotatelogs.UTC),
)This is an alternative to the WithClock option. Instead of providing an
explicit clock, you can provide a location for you times. We will create
a Clock object that produces times in your specified location, and configure
the rotatelog to respect it.
Path where a symlink for the actual log file is placed. This allows you to always check at the same location for log files even if the logs were rotated
rotatelogs.New(
"/var/log/myapp/log.%Y%m%d",
rotatelogs.WithLinkName("/var/log/myapp/current"),
) // Else where
$ tail -f /var/log/myapp/current
Links that share the same parent directory with the main log path will get a special treatment: namely, linked paths will be RELATIVE to the main log file.
| Main log file name | Link name | Linked path |
|---|---|---|
| /path/to/log.%Y%m%d | /path/to/log | log.YYYYMMDD |
| /path/to/log.%Y%m%d | /path/to/nested/log | ../log.YYYYMMDD |
| /path/to/log.%Y%m%d | /foo/bar/baz/log | /path/to/log.YYYYMMDD |
If not provided, no link will be written.
Interval between file rotation. By default logs are rotated every 86400 seconds. Note: Remember to use time.Duration values.
// Rotate every hour
rotatelogs.New(
"/var/log/myapp/log.%Y%m%d",
rotatelogs.WithRotationTime(time.Hour),
)Time to wait until old logs are purged. By default no logs are purged, which certainly isn't what you want. Note: Remember to use time.Duration values.
// Purge logs older than 1 hour
rotatelogs.New(
"/var/log/myapp/log.%Y%m%d",
rotatelogs.WithMaxAge(time.Hour),
)The number of files should be kept. By default, this option is disabled.
Note: MaxAge should be disabled by specifing WithMaxAge(-1) explicitly.
// Purge logs except latest 7 files
rotatelogs.New(
"/var/log/myapp/log.%Y%m%d",
rotatelogs.WithMaxAge(-1),
rotatelogs.WithRotationCount(7),
)Sets the event handler to receive event notifications from the RotateLogs object. Currently only supported event type is FiledRotated
rotatelogs.New(
"/var/log/myapp/log.%Y%m%d",
rotatelogs.WithHandler(rotatelogs.HandlerFunc(func(e rotatelogs.Event) {
if e.Type() != rotatelogs.FileRotatedEventType {
return
}
// Do what you want with the data. This is just an idea:
storeLogFileToRemoteStorage(e.(*rotatelogs.FileRotatedEvent).PreviousFile())
})),
)Ensure a new file is created every time New() is called. If the base file name already exists, an implicit rotation is performed.
rotatelogs.New(
"/var/log/myapp/log.%Y%m%d",
rotatelogs.ForceNewFile(),
)Enable compress old log files with gzip.
rotatelogs.New(
"/var/log/myapp/log.%Y%m%d",
rotatelogs.Compress(),
)Specify custom log formatter for rotatelogs hook, default rotatelogs.NewTextFormatter(true)
rotatelogs.NewHook(
"/var/log/myapp/log.%Y%m%d",
rotatelogs.WithFormatter(rotatelogs.NewTextFormatter(true)),
)If you want to use rotatelogs package with logrus.Hook, rotatelogs provides a default implementation, which you can easily
embed rotatelogs package in your code without third-party hook implementation. And you can specify a customized logrus.Formatter
when you create hook.
rotatelogs.NewHook(
"/var/log/myapp/log.%Y%m%d",
rotatelogs.WithFormatter(rotatelogs.NewTextFormatter(true)),
)If you want to rotate files forcefully before the actual rotation time has reached,
you may use the Rotate() method. This method forcefully rotates the logs, but
if the generated file name clashes, then a numeric suffix is added so that
the new file will forcefully appear on disk.
For example, suppose you had a pattern of '%Y.log' with a rotation time of
86400 so that it only gets rotated every year, but for whatever reason you
wanted to rotate the logs now, you could install a signal handler to
trigger this rotation:
rl := rotatelogs.New(...)
signal.Notify(ch, syscall.SIGHUP)
go func(ch chan os.Signal) {
<-ch
rl.Rotate()
}()And you will get a log file name in like 2018.log.1, 2018.log.2, etc.