lager_elogfmt_formatter

A lager formatter for logfmt and structured logs.

Leverages lager metadata to simplify logging of messages consumed, for example, by Splunk and Librato.

Additional metadata passed to logging calls with lager (when using the lager parse transform) will be included in logs:

lager:error([{type, badarg}, {{count, "badarg"}, 1}], "msg='failed to parse: ~w'", [Input])

The output to this log call will include:

app=myapp application=my_api module=parser function=parse line=42 severity=error type=badarg count#myapp.badarg=1 msg='failed to parse: ...'

Setup & Configuration

Include lager_elogfmt_formatter in your rebar.config:

{deps, [
    {lager_elogfmt_formatter,
     {git, "https://github.com/heroku/lager_elogfmt_formatter.git", {tag, "1.1.0"}}}
]}

Set lager_elogfmt_formatter as formatter for a lager handler. There are the following configurations:

(Required) {app, string()}: Defines an app entry which is included in all log messages.
(Optional) {defaults, [{string(), string()}]}: Set other default entries which will occurr in all log messages.

A lager configuration example looks like this:

{lager, {
    [{handlers, [
        {lager_console_backend, info, {lager_elogfmt_formatter, [{app, "myapp"},
                                                                 {defaults, [{"key", "value"}]}
                                                                ]}
        }]
    }]}
}

Test

Run the unit tests and type checker with:

$ rebar3 eunit, dialyzer

kzemek/lager_elogfmt_formatter

lager_elogfmt_formatter

Setup & Configuration

Test