61 lines
2.3 KiB
Markdown
61 lines
2.3 KiB
Markdown
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# log15 [](https://godoc.org/gopkg.in/inconshreveable/log15.v2)
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Package log15 provides an opinionated, simple toolkit for best-practice logging in Go (golang) that is both human and machine readable. It is modeled after the Go standard library's [`io`](http://golang.org/pkg/io/) and [`net/http`](http://golang.org/pkg/net/http/) packages and is an alternative to the standard library's [`log`](http://golang.org/pkg/log/) package.
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## Features
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- A simple, easy-to-understand API
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- Promotes structured logging by encouraging use of key/value pairs
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- Child loggers which inherit and add their own private context
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- Lazy evaluation of expensive operations
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- Simple Handler interface allowing for construction of flexible, custom logging configurations with a tiny API.
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- Color terminal support
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- Built-in support for logging to files, streams, syslog, and the network
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- Support for forking records to multiple handlers, buffering records for output, failing over from failed handler writes, + more
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## Versioning
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The API of the master branch of log15 should always be considered unstable. Using a stable version
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of the log15 package is supported by gopkg.in. Include your dependency like so:
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```go
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import log "gopkg.in/inconshreveable/log15.v2"
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```
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## Examples
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```go
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// all loggers can have key/value context
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srvlog := log.New("module", "app/server")
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// all log messages can have key/value context
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srvlog.Warn("abnormal conn rate", "rate", curRate, "low", lowRate, "high", highRate)
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// child loggers with inherited context
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connlog := srvlog.New("raddr", c.RemoteAddr())
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connlog.Info("connection open")
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// lazy evaluation
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connlog.Debug("ping remote", "latency", log.Lazy(pingRemote))
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// flexible configuration
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srvlog.SetHandler(log.MultiHandler(
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log.StreamHandler(os.Stderr, log.LogfmtFormat()),
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log.LvlFilterHandler(
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log.LvlError,
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log.Must.FileHandler("errors.json", log.JsonHandler())))
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```
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## FAQ
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### The varargs style is brittle and error prone! Can I have type safety please?
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Yes. Use `log.Ctx`:
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```go
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srvlog := log.New(log.Ctx{"module": "app/server"})
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srvlog.Warn("abnormal conn rate", log.Ctx{"rate": curRate, "low": lowRate, "high": highRate})
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```
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## License
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Apache
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