How do you run and debug Ruby on Rails from Visual Studio Code?

Setup and Launch

1. Install the VS Code Ruby plugin (hit ⌘+⇧+P on macOS or ctrl+⇧+P elsewhere and type ext install in the prompt, then search for ruby)
2. Install some required Ruby gems

gem install ruby-debug-ide
gem install debase

3. Add a launch configuration in Visual Studio Code (example configuration shown below)

{
    "name": "Rails server",
    "type": "Ruby",
    "request": "launch",
    "cwd": "${workspaceRoot}",
    "program": "${workspaceRoot}/bin/rails",
    "env": {
        "PATH": "YOUR_PATH_HERE",
        "GEM_HOME": "YOUR_GEM_HOME_HERE",
        "GEM_PATH": "YOUR_GEM_PATH_HERE",
        "RUBY_VERSION": "YOUR_RUBY_VERSION_HERE"
    },
    "args": [
        "server"
    ]
}

In some cases you might not need to specify the env section. In other cases you can launch VS Code using the CLI (i.e. from the terminal), which on some systems automatically sets the correct environment variables.

4. Run!

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Troubleshooting

If you get the following error

Debugger terminal error: Process failed: spawn rdebug-ide ENOENT

Your environment variables (env) are most likely not set and the plugin cannot find the necessary binaries.

1. Make sure all gems are installed and try running bundler install --binstubs if you use bundler.
2. Make sure the env section is set in your launch configuration. Run the following shell command to generate your env:

printf "\n\"env\": {\n  \"PATH\": \"$PATH\",\n  \"GEM_HOME\": \"$GEM_HOME\",\n  \"GEM_PATH\": \"$GEM_PATH\",\n  \"RUBY_VERSION\": \"$RUBY_VERSION\"\n}\n\n"

---

Windows

Make sure to use the correct spelling (and capitalization) of the path variable, i.e. Path on Windows

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Sources:

• https://github.com/rubyide/vscode-ruby/issues/214#issuecomment-393111908
• https://www.reddit.com/r/vscode/comments/5w1acs/getting_error_debugger_terminal_error_process/
• How to extend $PATH in launch.json in Visual Studio Code?

I spent most of a day trying to solve this.

I ended up stripping my launch.json config down to the following:

"configurations": [
    {
       "name": "Rails server",
        "type": "Ruby",
        "request": "launch",
        "cwd": "${workspaceRoot}",
        "program": "/Users/mitch/.rvm/gems/ruby-2.3.0@gg_portal/bin/rails",
        "args": [
            "server"
        ],
        "useBundler": true,
        "pathToRDebugIDE": "/Users/mitch/.rvm/gems/ruby-2.3.0@gg_portal/gems/ruby-debug-ide-0.6.1",
        "pathToBundler": "/Users/mitch/.rvm/gems/ruby-2.3.0@gg_portal/wrappers/bundle",
        "showDebuggerOutput": true
    }

]

Firstly, especially if you're using RVM & have different Gemsets, make sure your paths are consistent with the correct Gemset.

What solved the problem for me was pathToBundler.

which bundle
/Users/mitch/.rvm/gems/ruby-2.3.0@gg_portal/bin/bundle

There looks to be some incompatibility around setting the path to the binstubs bundler (shown above) and the bundler pointed to from /wrappers/ (shown below), so changing pathToBundler to:

"pathToBundler": "/Users/mitch/.rvm/gems/ruby-2.3.0@gg_portal/wrappers/bundle",

solved the problem.

There is a kind of related discussion here:

https://github.com/rails/rails/issues/31193

which talks about binstubs though not specifically VSCode & debugging.