• About
  • Supported versions
• Installation
• Configuration
• Labels
• Running
  • RSpec
  • Minitest
  • Cucumber
  • Remote recording
  • Server process recording
• AppMap for VSCode
• Uploading AppMaps
• Development
  • Running tests
  • Using fixture apps
  • test/fixtures
  • spec/fixtures

About

appmap-ruby is a Ruby Gem for recording AppMaps of your code. "AppMap" is a data format which records code structure (modules, classes, and methods), code execution events (function calls and returns), and code metadata (repo name, repo URL, commit SHA, labels, etc). It's more granular than a performance profile, but it's less granular than a full debug trace. It's designed to be optimal for understanding the design intent and structure of code and key data flows.

There are several ways to record AppMaps of your Ruby program using the appmap gem:

• Run your tests (RSpec, Minitest, Cucumber) with the environment variable APPMAP=true. An AppMap will be generated for each spec.
• Run your application server with AppMap remote recording enabled, and use the AppLand browser extension to start, stop, and upload recordings.
• Wrap some code in an AppMap.record block, which returns JSON containing the code execution trace.

Once you have made a recording, there are two ways to view automatically generated diagrams of the AppMaps.

The first option is to load the diagrams directly in your IDE, using the AppMap extension for VSCode.

The second option is to upload them to the AppLand server using the AppLand CLI.

Supported versions

• Ruby 2.5, 2.6, 2.7
• Rails 5, 6

Support for new versions is added frequently, please check back regularly for updates.

Installation

Quick and easy setup of the AppMap gem for Rails - Watch Video

Add gem 'appmap' to beginning of your Gemfile. We recommend that you add the appmap gem to the :development, :test group. Your Gemfile should look something like this:

source 'https://rubygems.org'
git_source(:github) { |repo| "https://github.com/#{repo}.git" }

# Optional rubRuby version
# ruby '2.7.2'

group :development, :test do
  gem 'appmap'
end

Install with bundle install, as usual.

It's important to add the appmap gem before any other gems that you may want to instrument. There is more about this in the section on adding gems to the appmap.yml.

Railtie

If you are using Ruby on Rails, require the railtie after Rails is loaded.

# application.rb is a good place to do this, along with all the other railties.
# Don't require the railtie in environments that don't bundle the appmap gem.
require 'appmap/railtie' if defined?(AppMap).

application.rb

Add this line to application.rb, to enable server recording with APPMAP_RECORD=true:

module MyApp
  class Application < Rails::Application
    ...

    config.appmap.enabled = true if ENV['APPMAP_RECORD']

    ...
  end
end

Configuration

When you run your program, the appmap gem reads configuration settings from appmap.yml. Here's a sample configuration file for a typical Rails project:

# 'name' should generally be the same as the code repo name.
name: my_project
packages:
- path: app/controllers
- path: app/models
- path: app/jobs
- path: app/helpers
# Include the gems that you want to see in the dependency maps.
# These are just examples.
- gem: activerecord
- gem: devise
- gem: aws-sdk
- gem: will_paginate
exclude:
- MyClass
- MyClass#my_instance_method
- MyClass.my_class_method

• name Provides the project name (required)
• packages A list of source code directories which should be recorded.
• exclude A list of classes and/or methods to definitively exclude from recording.

packages

Each entry in the packages list is a YAML object which has the following keys:

• path The path to the source code directory. The path may be relative to the current working directory, or it may be an absolute path.
• gem As an alternative to specifying the path, specify the name of a dependency gem. When using gem, don't specify path. In your Gemfile, the appmap gem must be listed before any gem that you specify in your appmap.yml.
• exclude A list of files and directories which will be ignored. By default, all modules, classes and public functions are inspected. See also: global exclude list.
• shallow When set to true, only the first function call entry into a package will be recorded. Subsequent function calls within the same package are not recorded unless code execution leaves the package and re-enters it. Default: true when using gem, false when using path.

exclude

Optional list of fully qualified class and method names. Separate class and method names with period (.) for class methods and hash (#) for instance methods.

Labels

The AppMap data format provides for class and function labels, which can be used to enhance the AppMap visualizations, and to programatically analyze the data.

You can apply function labels using source code comments in your Ruby code. To apply a labels to a function, add a @label or @labels line to the comment which immediately precedes a function.

For example, if you add this comment to your source code:

class ApiKey
  # @labels provider.authentication security
  def authenticate(key)
    # logic to verify the key here...
  end
end

Then the AppMap metadata section for this function will include:

  {
    "name": "authenticate",
    "type": "function",
    "labels": [ "provider.authentication", "security" ]
  }

Running

RSpec

To record RSpec tests, follow these additional steps:

1) Require appmap/rspec in your spec_helper.rb before any other classes are loaded.

require 'appmap/rspec'

Note that spec_helper.rb in a Rails project typically loads the application's classes this way:

require File.expand_path("../../config/environment", __FILE__)

and appmap/rspec must be required before this:

require 'appmap/rspec'
require File.expand_path("../../config/environment", __FILE__)

2) Run the tests with the environment variable APPMAP=true:

$ APPMAP=true bundle exec rspec

Each RSpec test will output an AppMap file into the directory tmp/appmap/rspec. For example:

$ find tmp/appmap/rspec
Hello_says_hello_when_prompted.appmap.json

Minitest

To record Minitest tests, follow these additional steps:

1) Require appmap/minitest in test_helper.rb

require 'appmap/minitest'

Note that test_helper.rb in a Rails project typically loads the application's classes this way:

require_relative '../config/environment'

and appmap/minitest must be required before this:

require 'appmap/minitest'
require_relative '../config/environment'

2) Run your tests as you normally would with the environment variable APPMAP=true. For example:

$ APPMAP=true bundle exec rake test

or

$ APPMAP=true bundle exec ruby -Ilib -Itest test/*_test.rb

Each Minitest test will output an AppMap file into the directory tmp/appmap/minitest. For example:

$ find tmp/appmap/minitest
Hello_says_hello_when_prompted.appmap.json

Cucumber

To record Cucumber tests, follow these additional steps:

1) Require appmap/cucumber in support/env.rb:

require 'appmap/cucumber'

Be sure to require it before config/environment is required.

2) Create an Around hook in support/hooks.rb to record the scenario:

if AppMap::Cucumber.enabled?
  Around('not @appmap-disable') do |scenario, block|
    appmap = AppMap.record do
      block.call
    end

    AppMap::Cucumber.write_scenario(scenario, appmap)
  end
end

3) Run the tests with the environment variable APPMAP=true:

$ APPMAP=true bundle exec cucumber

Each Cucumber test will output an AppMap file into the directory tmp/appmap/cucumber. For example:

$ find tmp/appmap/cucumber
Hello_Says_hello_when_prompted.appmap.json

Remote recording

To manually record ad-hoc AppMaps of your Ruby app, use AppMap remote recording.

1. Add the AppMap remote recording middleware. For example, in config/initializers/appmap_remote_recording.rb:

if defined?(AppMap)
  require 'appmap/middleware/remote_recording'

  Rails.application.config.middleware.insert_after \
    Rails::Rack::Logger,
    AppMap::Middleware::RemoteRecording
end

1. Download and unpack the AppLand browser extension. Install into Chrome using chrome://extensions/. Turn on "Developer Mode" and then load the extension using the "Load unpacked" button.

2. Start your Rails application server. For example:

$ bundle exec rails server

1. Open the AppLand browser extension and push Start.

2. Use your app. For example, perform a login flow, or run through a manual UI test.

3. Open the AppLand browser extension and push Stop. The recording will be transferred to the AppLand website and opened in your browser.

Server process recording

Run your Rails server with APPMAP_RECORD=true. When the server exits, an appmap.json file will be written to the project directory. This is a great way to start the server, interact with your app as a user (or through it's API), and then view an AppMap of everything that happened.

Be sure and set WEB_CONCURRENCY=1, if you are using a webserver that can run multiple processes. You only want there to be one process while you are recording, otherwise they will both try and write appmap.json and one of them will clobber the other.

AppMap for VSCode

The AppMap extension for VSCode is a great way to onboard developers to new code, and troubleshoot hard-to-understand bugs with visuals.

Uploading AppMaps

https://app.land can be used to store, analyze, and share AppMaps.

For instructions on uploading, see the documentation of the AppLand CLI.

Development

Running tests

Before running tests, configure local.appmap to point to your local appmap-ruby directory.

$ bundle config local.appmap $(pwd)

Run the tests via rake:

$ bundle exec rake test

The test target will build the native extension first, then run the tests. If you need to build the extension separately, run

$ bundle exec rake compile

Using fixture apps

test/fixtures

The fixture apps in test/fixtures are plain Ruby projects that exercise the basic functionality of the appmap gem. To develop in a fixture, simply enter the fixture directory and bundle.

spec/fixtures

The fixture apps in spec/fixtures are simple Rack, Rails4, and Rails5 apps. You can use them to interactively develop and test the recording features of the appmap gem. These fixture apps are more sophisticated than test/fixtures, because they include additional resources such as a PostgreSQL database.

To build the fixture container images, first run:

$ bundle exec rake build:fixtures:all

This will build the appmap.gem, along with a Docker image for each fixture app.

Then move to the directory of the fixture you want to use, and provision the environment. In this example, we use Ruby 2.6.

$ export RUBY_VERSION=2.6
$ docker-compose up -d pg
$ sleep 10s # Or some reasonable amount of time
$ docker-compose run --rm app ./create_app

Now you can start a development container.

$ docker-compose run --rm -v $PWD/../../..:/src/appmap-ruby app bash
Starting rails_users_app_pg_1 ... done
root@6fab5f89125f:/app# cd /src/app
root@6fab5f89125f:/src/app# bundle config local.appmap /src/appmap-ruby
root@6fab5f89125f:/src/app# bundle update appmap

At this point, the bundle is built with the appmap gem located in /src/appmap, which is volume-mounted from the host. So you can edit the fixture code and the appmap code and run test commands such as rspec and cucumber in the container. For example:

root@6fab5f89125f:/src/app# bundle exec rspec
Configuring AppMap from path appmap.yml
....

Finished in 0.07357 seconds (files took 2.1 seconds to load)
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