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ruby / vscode-rdbg

VSCode Ruby rdbg Debugger
MIT License
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debugger ruby vscode vscode-extension

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VSCode Ruby rdbg Debugger

Ruby debugger to connect debug library which utilize recent Ruby's debug support features.

Requirement

You need to install latest debug gem and rdbg command should be in $PATH.

$ gem install debug

How to use

Launch without configuration

Without any configuration, you can use this debugger by "Start Debugging" (F5 key) if you activate .rb file.

You will see the "Debug command line" input dialog. Please specify your favorite command line you want to debug.

For example:

When you select a command line, the specified command will run on rdbg debugger, and VSCode will connect to the rdbg debugger with UNIX domain socket.

And new terminal is created (named rdbg). You can see stdout/err outputs and you can input stdin on rdbg terminal.

You can stop the programs

When the program stops, you can see "Call stack", "Variables" and you can set "Watch" expressions. On the debug console, you can input valid Ruby program and you will get an evaluation result on selected context ("Call stack").

See also: Debugging in Visual Studio Code

For developers: RUBY_DEBUG_DAP_SHOW_PROTOCOL=1 on rdbg terminal will show the all DAP protocol.

Launch with configurations

You can write your favorite setting in .vscode/launch.json.

To make a .vscode/launch.json with default settings, you only need to click "create a launch.json file" on the "Run and Debug" pane. And you will see the following default configurations.

{
        // Use IntelliSense to learn about possible attributes.
        // Hover to view descriptions of existing attributes.
        // For more information, visit: https://go.microsoft.com/fwlink/?linkid=830387
        "version": "0.2.0",
        "configurations": [
                {
                        "type": "rdbg",
                        "name": "Debug current file with rdbg",
                        "request": "launch",
                        "script": "${file}",
                        "args": [],
                        "askParameters": true
                },
                {
                        "type": "rdbg",
                        "name": "Attach with rdbg",
                        "request": "attach"
                }
        ]
}

It contains "Debug current file with rdbg" (launch) configuration and "Attach with rdbg" (attach) configuration. You can modify this configuration, and also you can add your favorite configuration like:

                {
                        "type": "rdbg",
                        "name": "Run rake test",
                        "request": "launch",
                        "command": "rake",
                        "script": "test", // launch rake test with debugger
                        "args": [],
                        "askParameters": false // Do not ask startup parameter any more
                },

You can use the following "launch" configurations.

Note that if you have a trouble by launching rdbg, please try to specify rdbgPath. Without this configuration, this extension simply calls rdbg in PATH.

Attach to the running Ruby process

You can attach to a Ruby process which run with an opening debugger port.

The following commands starts the foo.rb with opening debug port. There are more methods to open the port. See more for ruby/debug: Debugging functionality for Ruby.

# With rdbg command
$ rdbg --open foo.rb              # open debug port. -O is short for --open
$ rdbg -n -O foo.rb               # do not stop at the beginning of application
$ rdbg -O -c -- bundle exec rspec # run rspec with remote

# With debug/open lib
$ ruby -r debug/open foo.rb
$ ruby -r debug/open_nonstop foo.rb # do not stop at the beginning of application

# If your application requires debug/open (or debug/open_nonstop) explicitly, of course -r is not needed.
$ ruby foo.rb

# With debug lib with RUBY_DEBUG_OPEN
$ RUBY_DEBUG_OPEN=true ruby -r debug foo.rb

# If your application requires debug explicitly, of course -r is not needed.
$ RUBY_DEBUG_OPEN=true ruby foo.rb

# If your Gemfile has a line `gem 'debug'` with Rails, you only need to launch it with the `RUBY_DEBUG_OPEN` envval.
$ RUBY_DEBUG_OPEN=true rails server

After that, you can connect to the debug port. This extension searches opening debugger port and attach to that port by running Attach with rdbg (select it on the top of "RUN AND DEBUG" pane and push the green "Start Debugging" button).

You can specify the following "attach" configurations.

Without debugPort configuration, the

With debugPort, you can attach to TCP/IP debug port.

localfsMap is helpful if you run the debuggee and share the same file system with another name in debuggee.

For example, running a docker container with -v option (and --network=host to communicate with the host and a docker container) option like that:

$ docker run --network=host -it -v `pwd`:/app/ --rm ruby bash
/:# cd app
/app:# rdbg -O --port=12345 target.rb

In this case, the current directory of host (${workspaceFolder}) is shared with the name /app in a container and VSCode on the host can connect to the debuggee process in a container by TCP/IP port 12345. The launch.json configuration should be:

        {
            "type": "rdbg",
            "name": "Attach with rdbg (tcp 12345)", // Specify your favorite name
            "request": "attach",
            "debugPort": "localhost:12345",
            "localfsMap": "/app:${workspaceFolder}"
        }

Selecting a version manager

In order to launch the debugger using the correct Ruby version, rdbg allows configuring your preferred version manager, which is used to activate the Ruby environment with extension settings (or settings.json).

// Default value is "none" for not using a version manager to activate the environment
// Available managers are shadowenv, chruby, asdf, rbenv and rvm

{
  // User settings
  "rdbg.rubyVersionManager": "none"
}

If you are using rbenv configured with a login shell (on bash or zsh), you do not need to specify this configuration because vscode-rdbg will launch ruby command with login shell setting like bash -lic ruby .... With this configuration, vscode-rdbg will launch simply ruby command. This configuration will be useful if you are using other environment such as chruby and so on.

Acknowledgement