Web Console

To develop the Web Console browser extensions, clone the repository, install dependencies, and run the Chrome extension task using Rake.

Note: This process requires having git, bundle, and rake installed on your system.

$ git clone https://github.com/rails/web-console.git
$ cd web-console
$ bundle install
$ bundle exec rake ext:chrome:run

Add web-console to your Gemfile within the :development group to use it for debugging your Rails application.

group :development do
  gem 'web-console'
end

Since the interactive console executes arbitrary Ruby code, you can inspect the current scope by calling standard Ruby methods:

• Use local_variables to see local variables.
• Use instance_variables to see instance variables.

The console method is defined in Kernel and can be invoked anywhere in your application code to launch an interactive Ruby session in your browser.

• In a view: Calling <% console %> displays the console within the current page in the context of the view binding.
• In a controller: Calling console inside an action launches the console in the context of that controller action.

Note: Only one console invocation per request is allowed. Attempting multiple invocations will raise a WebConsole::DoubleRenderError.

By default, only IPv4 and IPv6 localhosts are allowed access. Use config.web_console.permissions to grant access to specific IP addresses or entire networks.

Note that IPv4 and IPv6 localhosts are always allowed and cannot be revoked via this setting.

# Allow a single IP
class Application < Rails::Application
  config.web_console.permissions = '192.168.0.100'
end

# Allow a whole private network
Rails.application.configure do
  config.web_console.permissions = '192.168.0.0/16'
end

Web Console uses a permissions system to restrict access to the console interface to specific IP networks. By default, 127.0.0.0/8, ::1, and ::ffff:127.0.0.0/104 (localhost) are always permitted.

You can customize the allowed networks by providing a list of network strings or IPAddr objects to the permissions configuration. The system automatically normalizes these inputs and ensures localhost remains accessible.

When a console cannot be rendered (due to IP restrictions or content type), Web Console prints a message to the server logs. To suppress these messages, set config.web_console.whiny_requests to false.

Rails.application.configure do
  config.web_console.whiny_requests = false
end

To customize the appearance of the console, you can override its templates. Set config.web_console.template_paths to a directory containing your custom style.css and other template files.

Rails.application.configure do
  config.web_console.template_paths = 'app/views/web_console'
end

By default, the Web Console middleware is mounted at /__web_console. You can change this path using config.web_console.mount_point.

Rails.application.configure do
  config.web_console.mount_point = '/path/to/web_console'
end

If the console appears on error pages but not when you explicitly call console, it is likely due to Rack::Deflater. Ensure WebConsole::Middleware is used after Rack::Deflater.

The easiest fix is to insert Rack::Deflater as early as possible in your middleware stack:

Rails.application.configure do
  config.middleware.insert(0, Rack::Deflater)
end

Web Console sessions are stored in memory. If you are using a multi-process server (like Unicorn), you may see 'unavailable session' errors because a subsequent request might hit a different worker process that does not have the session in its memory.

Solution: Configure your server to serve requests from a single process during development. For example, if using Passenger, enable sticky sessions.