logrus/README.md

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# Logrus
Logrus is a simple, opinionated logging package for Go. It has three debugging
levels:
* `LevelDebug`: Debugging, usually turned off for deploys.
* `LevelInfo`: Info, useful for monitoring in production.
* `LevelWarning`: Warnings that should definitely be noted. These are sent to
`airbrake`.
* `LevelFatal`: Fatal messages that causes the application to crash. These are
sent to `airbrake`.
## Usage
The global logging level is set by: `logrus.Level = logrus.{LevelDebug,LevelWarning,LevelFatal}`.
Note that for `airbrake` to work, `airbrake.Endpoint` and `airbrake.ApiKey`
should be set.
There is a global logger, which new loggers inherit their settings from when
created (see example below), such as the place to redirect output. Logging can
be done with the global logging module:
```go
logrus.Debug("Something debugworthy happened: %s", importantStuff")
logrus.Info("Something infoworthy happened: %s", importantStuff")
logrus.Warning("Something bad happened: %s", importantStuff")
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// Reports to Airbrake
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logrus.Fatal("Something fatal happened: %s", importantStuff")
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// Reports to Airbrake
// Then exits
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```
Types are encouraged to include their own logging object. This allows to set a
context dependent prefix to know where a certain message is coming from, without
cluttering every single message with this.
```go
type Walrus struct {
TuskSize uint64
Sex bool
logger logrus.Logger
}
func NewWalrus(tuskSize uint64, sex bool) *Walrus {
return &Walrus{
TuskSize: tuskSize,
Sex: bool,
logger: logrus.NewLogger("Walrus"),
}
}
func (walrus *Walrus) Mate(partner *Walrus) error {
if walrus.Sex == partner.Sex {
return errors.New("Incompatible mating partner.")
}
walrus.logger.Info("Walrus with tusk sizes %d and %d are mating!", walrus.TuskSize, partner.TuskSize)
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// Generates a logging message: <timestamp> [Info] [Walrus] Walrus with tusk sizes <int> and <int> are mating!
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// Walrus mating happens here
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return nil
}
```