alephant-logger-json

Alephant::Logger::JSON

JSON logging driver for the alephant-logger gem.

Installation

Add this line to your application's Gemfile:

gem 'alephant-logger-json'

And then execute:

$ bundle

Or install it yourself as:

$ gem install alephant-logger-json

Usage

require "alephant/logger"
require "alephant/logger/json"

json_driver = Alephant::Logger::JSON.new "path/to/logfile.log"

logger = Alephant::Logger.setup json_driver
logger.info({ "some_field" => "some_value", "other_field" => "other_value" })

Nesting

By default, nested JSON values are flattened to strings. To enable nesting, provided that your log analysis tooling supports that, create Alephant::Logger::JSON as follows:

Alephant::Logger::JSON.new("path/to/logfile.log", :nesting => true)

Distributed Tracing

The logger will set a key of uuid to n/a by default for each log request.

This value can be changed by providing a lambda function that contains the logic to determine this value.

There are two methods available to help you:

• Alephant::Logger::JSON.session?: boolean response checking if @@session has been set
• Alephant::Logger::JSON.session: accepts a lambda function (its return value is internally assigned to @@session)

When using tracing, you'll need to provide a binding context as the first argument to your log level method calls.

This is to resolve issues with lambda's scope availability. See Kernal#binding for more details.

Example usage:

logger.info(binding, :foo => :bar)

If no binding is provided then tracing is ignored and the logger falls back to its default value.

Note: you can hide the binding necessity behind an abstraction layer if you prefer

Logging Levels

The logger includes an option to define a desired logging level. Only log levels that are equal to or higher than the desired level will be logged. The logger defaults to the lowest level 0 i.e. :debug when a desired level is undefined.

Example

# Hierarchical Log levels
# 0 => debug
# 1 => info
# 2 => warn
# 3 => error

# When Default level :debug
json_logger = Alephant::Logger::JSON.new("path/to/logfile.log")

# Log all levels >= 0
json_logger.info "This will log"

# When log level is defined
json_logger = Alephant::Logger::JSON.new("path/to/logfile.log", level: :info)

# log all levels >= 1

json_logger.debug "This will NOT log"
json_logger.info "This will log"

Note: The logger expects the desired level to be defined as a Symbol, String or Integer type.

Contributing

1. Fork it ( https://github.com/BBC-News/alephant-logger-json/fork )
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Add some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create a new Pull Request