select_rails_log

select_rails_log is a tool for extracting request logs from Rails log files.

It can be used during development to identify bottlenecks in the application or for small-scale benchmarking.

The following extraction criteria can be specified:

  • Request ID
  • Controller name and action name
  • HTTP method and status code
  • Request date and time range
  • Response time range
  • String matching

The extracted logs can be formatted and output in the following formats:

  • Text
  • JSON, JSONL
  • TSV
  • Raw log

Additionally, the tool can aggregate and output metrics such as response times for the extracted requests:

  • Percentiles by controller and action
  • Box plots by controller and action
  • Histograms for the overall extraction results

Installation

Install the gem by executing:

gem install select_rails_log

Usage

select_rails_log can process logs that include timestamps and Request-IDs.

To enable this, first configure the appropriate settings file, such as config/environments/development.rb, as follows:

config.log_tags = [:request_id]
config.log_formatter = ::Logger::Formatter.new

Sample session

Here are some usage examples.

To output a box plot for an overview, use the following command:

select_rails_log log/development.log --boxplot

The result will be output as follows:

boxplot

Next, let’s examine the response time distribution for ActiveStorage::Representations::RedirectController#show, which had significant variance:

select_rails_log log/development.log -A 'ActiveStorage::Representations::RedirectController#show' --histgram

histgram

Finally, let’s take a closer look at requests that took particularly long, specifically those over 400ms:

select_rails_log log/development.log -A 'ActiveStorage::Representations::RedirectController#show' -D 400..

text

Development

After checking out the repo, run bin/setup to install dependencies. Then, run rake test-unit to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and the created tag, and push the .gem file to rubygems.org.

Contributing

Bug reports and pull requests are welcome on GitHub at https://github.com/arika/select_rails_log. This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the code of conduct.

License

The gem is available as open source under the terms of the MIT License.

Code of Conduct

Everyone interacting in the SelectRailsLog project's codebases, issue trackers, chat rooms and mailing lists is expected to follow the code of conduct.