go-llog

The leven logging library

A simple general purpose logging library with multiple logging levels

Goals

The goal in llog is to write logs which have a general, static error message attached to them, describing what kind of an message happened and at what step it happened, but leaving out any context about the message (such as which user caused it, or what a particular parameter to a function was). The context is then provided in the form of optional key/value pairs, which can then be easily parsed by something like elk.

The benefits of this system is that it makes it very easy to categorize messages, and also very easy to scan all messages across services for a particular pattern. For instance, if you always include the IP address in the key/value set across all projects, you can very easily determine all the actions taken by a particular IP address.

Usage

import "github.com/levenlabs/go-llog"

func main() {
    llog.Info("Here's a generic log message!")
    llog.Error("an error happened", llog.KV{"userID":1111, "err": err, "sky": "blue"})
}

These will output:

~ INFO -- Here's a generic log message!
~ ERROR -- an error happened -- userID="1111" err="some error" sky="blue"

log.Logger

If you need a log.Logger interface you can use NewLogger(level, KV) and it will take each string sent to the Logger interface and log it via the default llog instance with the sent level and with the sent KV.

You can also send filter functions into NewLogger if you wish to filter out spammy or annoying log messages.

Once golang/go#13182 is resolved and there is a better interface we expect that the above solution would be depreated in favor of the new interface.

Tests

If you have logging output during tests, the asynchronous nature of the logging might end up mangling the "--- PASS: Function" output which could cause CI parsing to think a test failed. You should set BlockByDefault to true during tests if that is affecting you.