slogger

Slogger is a logging library for Go.

Slogger supports multiple appenders including an asynchronous appender and a rolling file appender.

Installing

Slogger can be installed via go get :

go get github.com/mongodb/slogger/v2/slogger

Example

At the core of slogger is the Logger type. Here is an example where we create a Logger with a StringAppender.

package main

import (
	"github.com/mongodb/slogger/v2/slogger"

	"bytes"
	"fmt"
)

func main() {
	buffer := new(bytes.Buffer)
	appender := slogger.StringAppender{buffer}
	logger := slogger.Logger{"", []slogger.Appender{appender}, 0, nil}

	logger.Logf(slogger.OFF, "Here is a sample log line: %v", 1)
	logger.Logf(slogger.OFF, "Here's another one: %v", 2)
	fmt.Print(buffer)
}

The above code prints:

[2016/02/25 14:35:10.168] [.off] [proc.c:main:247] Here is a sample log line: 1
[2016/02/25 14:35:10.168] [.off] [proc.c:main:247] Here's another one: 2

Some of slogger's appenders can be composed. For example, StringAppender does not respect logging levels, but we can create a FilterAppender that does. We can compose them to create an appender that pays attention to logging levels and outputs to a string.

package main

import (
	"github.com/mongodb/slogger/v2/slogger"

	"bytes"
	"fmt"
)

func main() {
	buffer := new(bytes.Buffer)
	appender := slogger.LevelFilter(slogger.INFO, slogger.StringAppender{buffer})
	logger := slogger.Logger{"", []slogger.Appender{appender}, 0, nil}

	logger.Logf(slogger.INFO, "This log line will make it through")
	logger.Logf(slogger.DEBUG, "This log line won't")
	fmt.Print(buffer)
}

The above code prints:

[2016/02/25 14:41:56.420] [.info] [slogger2.go:main:15] This log line will make it through

Other appenders include an AsyncAppender, a RetainingLevelFilterAppender, and a RollingFileAppender. See the code for details.

Contributing

1. Sign the MongoDB Contributor Agreement.
2. Fork the repository.
3. Make your changes.
4. Ensure that the tests pass by running ./run-tests.
5. Submit a pull request.

License

Slogger is made available under the Apache License version 2.