cloudflared-mirror/vendor/github.com/rifflock/lfshook/README.md

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# Local Filesystem Hook for Logrus
[![GoDoc](https://godoc.org/github.com/rifflock/lfshook?status.svg)](http://godoc.org/github.com/rifflock/lfshook)
Sometimes developers like to write directly to a file on the filesystem. This is a hook for [`logrus`](https://github.com/sirupsen/logrus) which designed to allow users to do that. The log levels are dynamic at instantiation of the hook, so it is capable of logging at some or all levels.
## Example
```go
import (
"github.com/rifflock/lfshook"
"github.com/sirupsen/logrus"
)
var Log *logrus.Logger
func NewLogger() *logrus.Logger {
if Log != nil {
return Log
}
pathMap := lfshook.PathMap{
logrus.InfoLevel: "/var/log/info.log",
logrus.ErrorLevel: "/var/log/error.log",
}
Log = logrus.New()
Log.Hooks.Add(lfshook.NewHook(
pathMap,
&logrus.JSONFormatter{},
))
return Log
}
```
### Formatters
`lfshook` will strip colors from any `TextFormatter` type formatters when writing to local file, because the color codes don't look great in file.
If no formatter is provided via `lfshook.NewHook`, a default text formatter will be used.
### Log rotation
In order to enable automatic log rotation it's possible to provide an io.Writer instead of the path string of a log file.
In combination with packages like [file-rotatelogs](https://github.com/lestrrat-go/file-rotatelogs) log rotation can easily be achieved.
```go
package main
import (
rotatelogs "github.com/lestrrat-go/file-rotatelogs"
"github.com/rifflock/lfshook"
"github.com/sirupsen/logrus"
)
var Log *logrus.Logger
func NewLogger() *logrus.Logger {
if Log != nil {
return Log
}
path := "/var/log/go.log"
writer := rotatelogs.New(
path+".%Y%m%d%H%M",
rotatelogs.WithLinkName(path),
rotatelogs.WithMaxAge(time.Duration(86400)*time.Second),
rotatelogs.WithRotationTime(time.Duration(604800)*time.Second),
)
logrus.Hooks.Add(lfshook.NewHook(
lfshook.WriterMap{
logrus.InfoLevel: writer,
logrus.ErrorLevel: writer,
},
&logrus.JSONFormatter,
))
Log = logrus.New()
Log.Hooks.Add(lfshook.NewHook(
pathMap,
&logrus.JSONFormatter{},
))
return Log
}
```
### Note:
User who run the go application must have read/write permissions to the selected log files. If the files do not exists yet, then user must have permission to the target directory.