tensiondriven / logger

Elixir error logger development

Logger

Note: this project has been merged into Elixir and is available since v0.15.0

The goal of this project is to explore a Logger implementation that will be included in Elixir. One of the big influences for this project is Lager and Andrew's talk on the matter.

Obviously, one of the first questions may be: why not Lager? We need a project that knows how to log terms in Elixir syntax, in particular, using the Inspect protocol. That's why the focus of this project is on the error handler and not on the error logger itself.

By default Logger will run on top of OTP's error_logger and we will include an API that mostly wraps the error_logger one.

Installation

Add :logger as a dependency to your mix.exs file:

defp deps do
  [{:logger, github: "josevalim/logger"}]
end

You should also update your application list to include :logger:

def application do
  [applications: [:logger]]
end

Logger is not published on Hex as we intend to merge it into Elixir before 1.0.

Features

Below we detail the features we plan to include in the short-term, long-term or when it does not apply.

Short-term features (before 1.0):

• done A Logger module to log warning, info and error messages.
• done A backend that can print log messages using Elixir terms.
• done A watcher to ensure the handler is registered even if it crashes.
• done Data truncation so we never try to log a message of megabytes of size.
• done A way to lazily calculate the log messages to avoid generating expensive log messages that won't be used.
• done An error handler that supports a threshold (as seen in Lager) to limit the amount of messages we print per second (so we never bring the node down due to excessive messages, see cascading-failures).
• done Switching between sync and async modes.
• done Custom formatting.
• done Metadata (via options and process dictionary).
• done Error translators, so we can translate GenServer and other OTP errors into something more palatable.
• done Custom backends.

Long-term features (after 1.0):

• done SASL reports.
• Logging to files and log rotation.
• Tracing.

LICENSE

This project is under the same LICENSE as Elixir.