How do you develop in Gemfile-less mode?

[jconley88]

I haven't found a straightforward way to run my local ruby-lsp server in standalone mode for debugging. I'm wondering how others are approaching development in similar scenarios, if there is a more direct approach that I have missed and otherwise if support could be added for this.

In the meantime, I've found a workaround that might be helpful to others facing the same issue. I'm sharing it here in case it assists someone, and I'd also appreciate any insights or alternative solutions.

The Issue

My launch config for debugging the extension opens another (Gemfile-less) workspace:

    "args": [
        "/path/to/target/workspace",
        "--extensionDevelopmentPath=${workspaceFolder}",
        "--disable-extensions"
    ],

The target workspace does not have a Gemfile and the path does not end in ruby-lsp, so getLspExecutables resolves to just ruby-lsp which loads my installed gem instead of my local repo. I was able to get the workspace to load my local copy if I set a custom Gemfile that has gem 'ruby-lsp', path: '/path/to/my/local/ruby-lsp'. Unfortunately, this obviously starts the server in bundle mode rather than standalone mode. Without a custom bundle, the server from my local copy of ruby-lsp is only started if the extension is running from within ruby-lsp itself.

The Workaround

For now, I added a ruby-lsp symlink in my target workspace that points to my local exe/ruby-lsp. This works! I had cursor create tasks to link and unlink automatically.

launch.json

    "preLaunchTask": "create-ruby-lsp-symlink",
    "postDebugTask": "remove-ruby-lsp-symlink"

tasks.json

{
	"label": "create-ruby-lsp-symlink",
	"type": "shell",
	"command": "ln",
	"args": [
		"-s",
		"/path/to/ruby-lsp/exe/ruby-lsp",
		"/path/to/target/workspace/ruby-lsp"
	],
	"group": "build",
	"presentation": {
		"echo": true,
		"reveal": "silent",
		"focus": false,
		"panel": "shared",
		"showReuseMessage": true,
		"clear": false
	},
	"problemMatcher": []
},
{
	"label": "remove-ruby-lsp-symlink",
	"type": "shell",
	"command": "rm",
	"args": [
		"-f",
		"path/to/target/workspace/ruby-lsp"
	],
	"group": "build",
	"presentation": {
		"echo": true,
		"reveal": "silent",
		"focus": false,
		"panel": "shared",
		"showReuseMessage": true,
		"clear": false
	},
	"problemMatcher": []
}

[vinistock]

Honestly, I haven't found a good solution for this yet, so we'll take any ideas. What I normally do, especially when investigating a bug, is this:

1. Open VS Code on the bundle-less project
2. Restart the LSP in debug mode with the command Debug the Ruby LSP server
3. Use a launch task to attach to the current Ruby LSP process
4. Then I put breakpoints in the installed LSP's code and debug step by step

It's definitely not the most straight forward thing. We do have a rubyLsp.branch setting, which allows you to use a version of the LSP that exists on GitHub. Maybe we can make that setting accept a file path as well and then you can point to your local copy even without a bundle. What do you think?

It would require some changes though as the Gemfile we generate in .ruby-lsp/Gemfile would need to detect if branch is a branch or a file path and then use the appropriate entry:

gem "ruby-lsp", github: "Shopify/ruby-lsp", branch: the_branch
# vs
gem "ruby-lsp", path: "/path/to/local/copy"

[jconley88]

Yes, I'd like the option to configure the path to the server, so I can easily run my local changes in any workspace. I think it should be a separate configuration setting, as they are conceptually different. It also may not be straightforward to determine whether a branch or file path was intended since branches can contain slashes.

My preferred solution would involve something temporary that I could set in the launch configuration, but I don't think VS Code supports this.

[vinistock]

Indeed, I don't think there's an easy way to do this with launch tasks. I think the easiest path forward would probably be a setting and I agree that a separate setting makes sense - although we'll need to prohibit setting both branch and path at the same time.

Let me know if you want to take a stab at this! It would be great to have this.

[jconley88]

Yeah, I'd love to get a PR together! Shall I make an issue to track it?

[vinistock]

Sure! I'll close this discussion and we can create an issue for the task itself. Don't hesitate to reach out if you want to discuss the implementation!