LokiLogger

LokiLogger is an Elixir logger backend providing support for Logging to Grafana Loki

Known issues

• "works-on-my-machine" level of quality. Love to get your feedback in the repo's Github issues

TODO

• async http call to backend.
• snappy compressed proto format in the HTTP Body instead of JSON.
• proper unit tests.
• http post retry strategy on temporary loki backend failure or network hiccups.
• authentication with basic auth and/or Oauth2 reverse proxy.
• support for tenant header (X-Scope-OrgID) in multi-tenancy scenario's.
• CI build integration (e.g. TravisCI)

Installation

The package can be installed by adding loki_logger to your list of dependencies in mix.exs:

def deps do
  [
    {:loki_logger, "~> 0.1.0"}
  ]
end

Configuration

Elixir Project

Loki Logger's behavior is controlled using the application configuration environment:

• loki_host : the hostname of the syslog server e.g. http://localhost:3100
• loki_labels : the Loki log labels used to select the log stream in e.g. Grafana
• level: logging threshold. Messages "above" this threshold will be discarded. The supported levels, ordered by precedence are :debug, :info, :warn, :error.
• format: the format message used to print logs. Defaults to: "$metadata level=$level $levelpad$message". It may also be a {module, function} tuple that is invoked with the log level, the message, the current timestamp and the metadata.
• metadata: the metadata to be printed by $metadata. Defaults to to :all, which prints all metadata.
• max_buffer: the amount of entries to buffer before posting to the Loki REST api. Defaults to 32.

For example, the following config/config.exs file sets up Loki Logger using level debug, with application label loki_logger_library.

use Mix.Config

config :logger,
       backends: [LokiLogger]

config :logger, :loki_logger,
       level: :debug,
       format: "$metadata level=$level $levelpad$message",
       metadata: :all,
       max_buffer: 300,
       loki_labels: %{application: "loki_logger_library", elixir_node: node()},
       loki_host: "http://localhost:3100"

License

Loki Logger is copyright (c) 2019 Ward Bekker

The source code is released under the Apache v2.0 License.

Check LICENSE for more information.