80 lines
3.5 KiB
Markdown
80 lines
3.5 KiB
Markdown
# go-log
|
|
|
|
[](http://ipn.io)
|
|
[](http://ipfs.io/)
|
|
[](http://webchat.freenode.net/?channels=%23ipfs)
|
|
[](https://github.com/RichardLitt/standard-readme)
|
|
[](https://godoc.org/github.com/ipfs/go-log)
|
|
[](https://travis-ci.org/ipfs/go-log)
|
|
|
|
<!---[](https://coveralls.io/github/ipfs/go-log?branch=master)--->
|
|
|
|
|
|
> The logging library used by go-ipfs
|
|
|
|
It currently uses a modified version of [go-logging](https://github.com/whyrusleeping/go-logging) to implement the standard printf-style log output.
|
|
|
|
## Install
|
|
|
|
```sh
|
|
go get github.com/ipfs/go-log
|
|
```
|
|
|
|
## Usage
|
|
|
|
Once the package is imported under the name `logging`, an instance of `EventLogger` can be created like so:
|
|
|
|
```go
|
|
var log = logging.Logger("subsystem name")
|
|
```
|
|
|
|
It can then be used to emit log messages, either plain printf-style messages at six standard levels or structured messages using `Start`, `StartFromParentState`, `Finish` and `FinishWithErr` methods.
|
|
|
|
## Example
|
|
|
|
```go
|
|
func (s *Session) GetBlock(ctx context.Context, c *cid.Cid) (blk blocks.Block, err error) {
|
|
|
|
// Starts Span called "Session.GetBlock", associates with `ctx`
|
|
ctx = log.Start(ctx, "Session.GetBlock")
|
|
|
|
// defer so `blk` and `err` can be evaluated after call
|
|
defer func() {
|
|
// tag span associated with `ctx`
|
|
log.SetTags(ctx, map[string]interface{}{
|
|
"cid": c,
|
|
"block", blk,
|
|
})
|
|
// if err is non-nil tag the span with an error
|
|
log.FinishWithErr(ctx, err)
|
|
}()
|
|
|
|
if shouldStartSomething() {
|
|
// log message on span associated with `ctx`
|
|
log.LogKV(ctx, "startSomething", true)
|
|
}
|
|
...
|
|
}
|
|
```
|
|
## Tracing
|
|
|
|
`go-log` wraps the [opentracing-go](https://github.com/opentracing/opentracing-go) methods - `StartSpan`, `Finish`, `LogKV`, and `SetTag`.
|
|
|
|
`go-log` implements its own tracer - `loggabletracer` - based on the [basictracer-go](https://github.com/opentracing/basictracer-go) implementation. If there is an active [`WriterGroup`](https://github.com/ipfs/go-log/blob/master/writer/option.go) the `loggabletracer` will [record](https://github.com/ipfs/go-log/blob/master/tracer/recorder.go) span data to the `WriterGroup`. An example of this can be seen in the [`log tail`](https://github.com/ipfs/go-ipfs/blob/master/core/commands/log.go) command of `go-ipfs`.
|
|
|
|
Third party tracers may be used by calling `opentracing.SetGlobalTracer()` with your desired tracing implementation. An example of this can be seen using the [`go-jaeger-plugin`](https://github.com/ipfs/go-jaeger-plugin) and the `go-ipfs` [tracer plugin](https://github.com/ipfs/go-ipfs/blob/master/plugin/tracer.go)
|
|
|
|
## Contribute
|
|
|
|
Feel free to join in. All welcome. Open an [issue](https://github.com/ipfs/go-log/issues)!
|
|
|
|
This repository falls under the IPFS [Code of Conduct](https://github.com/ipfs/community/blob/master/code-of-conduct.md).
|
|
|
|
### Want to hack on IPFS?
|
|
|
|
[](https://github.com/ipfs/community/blob/master/contributing.md)
|
|
|
|
## License
|
|
|
|
MIT
|