Rails API Logger

The simplest way to log API requests in your database.

The Rails API logger gem introduces a set of tools to log and debug API requests.

It works on two sides:

• Inbound requests: API exposed by your application
• Outbound requests: API invoked by your application

This gem has been extracted from various Renuo projects.

This gem creates two database tables to log the following information:

• path the path/url invoked
• method the method used to invoke the API (get, post, put, etc...)
• request_body what was included in the request body
• response_body what was included in the response body
• response_code the HTTP response code of the request
• started_at when the request started
• ended_at when the request finished

Installation

Add this line to your application's Gemfile:

gem 'rails_api_logger'

And then execute:

bundle install
bin/rails g rails_api_logger:install
bin/rails db:migrate

This will generate two tables inbound_request_logs and outbound_request_logs. These tables will contain the logs.

Ensure logging of data

RailsApiLogger can use a separate database, to ensure that the logs are written in the database even if a surrounding database transaction is rolled back.

Make sure to add the following in your config/environments/production.rb:

config.rails_api_logger.connects_to = { database: { writing: :api_logger } }

and configure a new database accordingly.

⚠️ If you skip this step, rails_api_logger will use your primary database but a rollback will also rollback the writing of logs If you are not on SQLite you can point also api_logger to the same database! By doing so you can use a single database but still guarantee the writing of logs in an isolated transaction.

Log Outbound Requests

Given an outbound request in the following format:

uri = URI('http://example.com/some_path?query=string')
http = Net::HTTP.start(uri.host, uri.port)
request = Net::HTTP::Get.new(uri)
response = http.request(request)

you can log it by doing the following:

uri = URI('http://example.com/some_path?query=string')
http = Net::HTTP.start(uri.host, uri.port)
request = Net::HTTP::Get.new(uri)

log = RailsApiLogger::OutboundRequestLog.from_request(request)

response = http.request(request)

log.response_body = response.body
log.response_code = response.code
log.save!

You can also use the provided logger class to do that in a simpler and safer manner:

uri = URI('https://example.com/some_path')
request = Net::HTTP::Post.new(uri)
request.body = { answer: 42 }.to_json
request.content_type = 'application/json'

response = RailsApiLogger::Logger.new.call(nil, request) do
  Net::HTTP.start(uri.host, uri.port, use_ssl: true) { |http| http.request(request) }
end

This will guarantee that the log is always persisted, even in case of errors.

Database Transactions Caveats

If you log your outbound requests inside of parent app transactions, your logs will not be persisted if the transaction is rolled-back. Use a separate database to prevent this.

Log Inbound Requests

If you are exposing some API you might be interested in logging the requests you receive. You can do so by adding this middleware in config/application.rb

config.middleware.insert_before Rails::Rack::Logger, RailsApiLogger::Middleware

this will by default only log requests that have an impact in your system (POST, PUT, and PATCH calls). If you want to log all requests (also GET ones) use

config.middleware.insert_before Rails::Rack::Logger, RailsApiLogger::Middleware, only_state_change: false

If you want to log only requests on a certain path, you can pass a regular expression:

config.middleware.insert_before Rails::Rack::Logger, RailsApiLogger::Middleware, path_regexp: /api/

If you want to log only requests on a certain host, you can also use a regular expression:

config.middleware.insert_before Rails::Rack::Logger, RailsApiLogger::Middleware, host_regexp: /api.example.com/

If you want to skip logging the response or request body of certain requests, you can pass a regular expression:

config.middleware.insert_before Rails::Rack::Logger, RailsApiLogger::Middleware,
                                skip_request_body_regexp: /api\/books/,
                                skip_response_body_regexp: /api\/letters/

In the implementation of your API, you can call any time attach_inbound_request_loggable(model) to attach an already persisted model to the log record.

For example:

def create
  @user = User.new(user_params)
  if @user.save
    attach_inbound_request_loggable(@user)
    render json: { id: @user.id }, status: :created
  else
    render json: @user.errors.details, status: :unprocessable_entity
  end
end

in the User model you can define:

has_many_inbound_request_logs

to be able to access the inbound logs attached to the model.

You also have has_many_outbound_request_logs and has_many_request_logs that includes both.

RailsAdmin integration

We provide here some code samples to integrate the models in RailsAdmin.

This configuration will give you some nice views, and searches to work with the logs efficiently.

%w[RailsApiLogger::InboundRequestLog RailsApiLogger::OutboundRequestLog].each do |logging_model|
  config.model logging_model do
    list do
      filters %i[method path response_code request_body response_body created_at]
      scopes [nil, :failed]

      include_fields :method, :path, :response_code, :created_at

      field :request_body, :string do
        visible false
        searchable true
        filterable true
      end

      field :response_body, :string do
        visible false
        searchable true
        filterable true
      end
    end

    show do
      include_fields :loggable, :method, :path, :response_code
      field(:created_at)
      field(:request_body) do
        formatted_value { "<pre>#{JSON.pretty_generate(bindings[:object].request_body)}</pre>".html_safe }
      end
      field(:response_body) do
        formatted_value { "<pre>#{JSON.pretty_generate(bindings[:object].response_body)}</pre>".html_safe }
      end
    end
  end
end

Development

After checking out the repo, run bin/setup to install dependencies. Then, run rake spec 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 tags, and push the .gem file to rubygems.org.

Contributing

Bug reports and pull requests are welcome on GitHub at https://github.com/renuo/rails_api_logger. This project is intended to be a safe, welcoming space for collaboration.

Try to be a decent human being while interacting with other people.

License

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