• Overview
• Usage
• Configuration

Overview

Lager (pronounced lAAger) is a logging framework for Erlang. Its purpose is to provide a more traditional way to perform logging in an erlang application that plays nicely with traditional UNIX logging tools like logrotate and syslog.

Features

• Finer grained log levels (debug, info, notice, warning, error, critical, alert, emergency)

• Logger calls are transformed using a parse transform to allow capturing Module/Function/Line/Pid information

• When no handler is consuming a log level (eg. debug) no event is even sent to the log handler

• Supports multiple backends, including console, file and syslog.

Usage

To use lager in your application, you need to define it as a rebar dep or have some other way of including it in erlang's path. You can then add the following option to the erlang compiler flags

  {parse_transform, lager_transform}

Alternately, you can add it to the module you which to compile with logging enabled:

  -compile([{parse_transform, lager_transform}]).

Once you have built your code with lager, you can then generate log messages by doing the following:

  lager:error("Some message")

Or:

  lager:warning("Some message with a term: ~p", [Term])

The general form is lager:Severity() where Severity is one of the log levels mentioned above.

Configuration

TODO