提交 b2322b7a 编写于 作者: S Simon Eskildsen

readme: encourage package level logging

上级 33c9d5ae
......@@ -45,22 +45,49 @@ time="2014-04-20 15:36:23.830626464 -0400 EDT" level="fatal" msg="The ice breaks
#### Example
Note again that Logrus is API compatible with the stdlib logger, so if you
remove the `log` import and create a global `log` variable as below it will just
work.
The simplest way to use Logrus is simply the package-level exported logger:
```go
package main
import (
"github.com/Sirupsen/logrus"
log "github.com/Sirupsen/logrus"
)
var log = logrus.New()
func main() {
log.WithFields(logrus.Fields{
"animal": "walrus"
}).Info("A walrus appears")
}
```
Note that it's completely api-compatible with the stdlib logger, so you can
replace your `log` imports everywhere with `log "github.com/Sirupsen/logrus"`
and you'll now have the flexibility of Logrus. You can customize it all you
want:
```go
package main
import (
"os"
log "github.com/Sirupsen/logrus"
"github.com/Sirupsen/logrus/hooks/airbrake"
)
func init() {
log.Formatter = new(logrus.JSONFormatter)
log.Formatter = new(logrus.TextFormatter) // default
// Log as JSON instead of the default ASCII formatter.
log.SetFormatter(logrus.JSONFormatter)
// Use the Airbrake hook to report errors that have Error severity or above to
// an exception tracker. You can create custom hooks, see the Hooks section.
log.AddHook(logrus_airbrake.AirbrakeHook)
// Output to stderr instead of stdout, could also be a file.
log.SetOuput(os.Stderr)
// Only log the warning severity or above.
log.SetLevel(logrus.WarnLevel)
}
func main() {
......@@ -81,12 +108,30 @@ func main() {
}
```
#### Package logging
For more advanced usage such as logging to multiple locations from the same
application, you can also create an instance of the `logrus` Logger:
Alike the stdlib logger, logrus exposes functions that you can use to log
to a default global logger. This is convenient to avoid passing a
`logrus.Logger` thorough your app's packages; you can simply setup `logrus
from your main package and use the package function directly accross your app.
```go
package main
import (
"github.com/Sirupsen/logrus"
)
// Create a new instance of the logger. You can have any number of instances.
var log = logrus.New()
func main() {
// The API for setting attributes is a little different than the package level
// exported logger. See Godoc.
log.Out = os.Sderr
log.WithFields(logrus.Fields{
"animal": "walrus",
"size": 10,
}).Info("A group of walrus emerges from the ocean")
}
```
#### Fields
......@@ -96,8 +141,6 @@ to send event %s to topic %s with key %d")`, you should log the much more
discoverable:
```go
log = logrus.New()
log.WithFields(logrus.Fields{
"event": event,
"topic": topic,
......@@ -122,10 +165,12 @@ multiple places simultaneously, e.g. syslog.
```go
// Not the real implementation of the Airbrake hook. Just a simple sample.
var log = logrus.New()
import (
log "github.com/Sirupsen/logrus"
)
func init() {
log.Hooks.Add(new(AirbrakeHook))
log.AddHook(new(AirbrakeHook))
}
type AirbrakeHook struct{}
......@@ -158,12 +203,12 @@ Logrus comes with built-in hooks. Add those, or your custom hook, in `init`:
```go
import (
"github.com/Sirupsen/logrus"
log "github.com/Sirupsen/logrus"
"github.com/Sirupsen/logrus/hooks/airbrake"
)
func init() {
log.Hooks.Add(new(logrus_airbrake.AirbrakeHook))
log.AddHook(new(logrus_airbrake.AirbrakeHook))
}
```
......@@ -191,7 +236,7 @@ that severity or anything above it:
```go
// Will log anything that is info or above (warn, error, fatal, panic). Default.
log.Level = logrus.InfoLevel
log.SetLevel(logrus.InfoLevel)
```
It may be useful to set `log.Level = logrus.DebugLevel` in a debug or verbose
......@@ -217,16 +262,18 @@ variable `Environment`, which is a string representation of the environment you
could do:
```go
import (
log "github.com/Sirupsen/logrus"
)
init() {
// do something here to set environment depending on an environment variable
// or command-line flag
log := logrus.New()
if Environment == "production" {
log.Formatter = new(logrus.JSONFormatter)
log.SetFormatter(logrus.JSONFormatter)
} else {
// The TextFormatter is default, you don't actually have to do this.
log.Formatter = new(logrus.TextFormatter)
log.SetFormatter(logrus.TextFormatter)
}
}
```
......@@ -258,7 +305,7 @@ default ones (see Entries section above):
type MyJSONFormatter struct {
}
log.Formatter = new(MyJSONFormatter)
log.SetFormatter(new(MyJSONFormatter))
func (f *JSONFormatter) Format(entry *Entry) ([]byte, error) {
// Note this doesn't include Time, Level and Message which are available on
......
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