# Clog [](https://travis-ci.org/go-clog/clog) [](https://godoc.org/gopkg.in/clog.v1) [](https://sourcegraph.com/github.com/go-clog/clog?badge)
Clog is a channel-based logging package for Go.
This package supports multiple logger adapters across different levels of logging. It uses Go's native channel feature to provide goroutine-safe mechanism on large concurrency.
## Installation
To use a tagged revision:
go get gopkg.in/clog.v1
To use with latest changes:
go get github.com/go-clog/clog
Please apply `-u` flag to update in the future.
### Testing
If you want to test on your machine, please apply `-t` flag:
go get -t gopkg.in/clog.v1
Please apply `-u` flag to update in the future.
## Getting Started
Clog currently has three builtin logger adapters: `console` , `file` , `slack` and `discord` .
It is extremely easy to create one with all default settings. Generally, you would want to create new logger inside `init` or `main` function.
```go
...
import (
"fmt"
"os"
log "gopkg.in/clog.v1"
)
func init() {
err := log.New(log.CONSOLE, log.ConsoleConfig{})
if err != nil {
fmt.Printf("Fail to create new logger: %v\n", err)
os.Exit(1)
}
log.Trace("Hello %s!", "Clog")
// Output: Hello Clog!
log.Info("Hello %s!", "Clog")
log.Warn("Hello %s!", "Clog")
...
}
...
```
The above code is equivalent to the follow settings:
```go
...
err := log.New(log.CONSOLE, log.ConsoleConfig{
Level: log.TRACE, // Record all logs
BufferSize: 0, // 0 means logging synchronously
})
...
```
In production, you may want to make log less verbose and asynchronous:
```go
...
err := log.New(log.CONSOLE, log.ConsoleConfig{
// Logs under INFO level (in this case TRACE) will be discarded
Level: log.INFO,
// Number mainly depends on how many logs will be produced by program, 100 is good enough
BufferSize: 100,
})
...
```
Console logger comes with color output, but for non-colorable destination, the color output will be disabled automatically.
### Error Location
When using `log.Error` and `log.Fatal` functions, the first argument allows you to indicate whether to print the code location or not.
```go
...
// 0 means disable printing code location
log.Error(0, "So bad... %v", err)
// To print appropriate code location mainly depends on how deep your call stack is,
// you need to try and verify
log.Error(2, "So bad... %v", err)
// Output: 2017/02/09 01:06:16 [ERROR] [...uban-builder/main.go:64 main()] ...
log.Fatal(2, "Boom! %v", err)
// Output: 2017/02/09 01:06:16 [FATAL] [...uban-builder/main.go:64 main()] ...
...
```
Calling `log.Fatal` will exit the program.
## File
File logger is more complex than console, and it has ability to rotate:
```go
...
err := log.New(log.FILE, log.FileConfig{
Level: log.INFO,
BufferSize: 100,
Filename: "clog.log",
FileRotationConfig: log.FileRotationConfig {
Rotate: true,
Daily: true,
},
})
...
```
## Slack
Slack logger is also supported in a simple way:
```go
...
err := log.New(log.SLACK, log.SlackConfig{
Level: log.INFO,
BufferSize: 100,
URL: "https://url-to-slack-webhook",
})
...
```
This logger also works for [Discord Slack ](https://discordapp.com/developers/docs/resources/webhook#execute-slackcompatible-webhook ) endpoint.
## Discord
Discord logger is supported in rich format via [Embed Object ](https://discordapp.com/developers/docs/resources/channel#embed-object ):
```go
...
err := log.New(log.DISCORD, log.DiscordConfig{
Level: log.INFO,
BufferSize: 100,
URL: "https://url-to-discord-webhook",
})
...
```
This logger also retries automatically if hits rate limit after `retry_after` .
## Credits
- Avatar is a modified version based on [egonelbre/gophers' scientist ](https://github.com/egonelbre/gophers/blob/master/vector/science/scientist.svg ).
## License
This project is under Apache v2 License. See the [LICENSE ](LICENSE ) file for the full license text.
