How to get nvim-dap and nvim-metals working with debugging for spark

[q-joshualeong]

Hi guys,

Im trying to setup my neovim to be able to debug my spark applications that are written in scala. I am wondering how to setup nvim-metals to be able to attach into the jvm of the spark submit process.

Does metals support this or im seeing that i may need nvim-jdtls.

Im trying to understand the nvim-dap docs for java mean when it says

local dap = require('dap')
dap.adapters.java = function(callback)
  -- FIXME:
  -- Here a function needs to trigger the `vscode.java.startDebugSession` LSP command
  -- The response to the command must be the `port` used below
  callback({
    type = 'server';
    host = '127.0.0.1';
    port = port;
  })
end

Ive also installed java-debug but dont quite understand its docs when it says

To use java-debug as a jdt.ls plugin, an LSP client has to launch jdt.ls with initializationOptions that contain the path to the built java-debug jar within a bundles array:

{
    "initializationOptions": {
        "bundles": [
            "path/to/microsoft/java-debug/com.microsoft.java.debug.plugin/target/com.microsoft.java.debug.plugin-<version>.jar"
        ]
    }
}

Editor extensions like vscode-java take care of this.

Once eclipse.jdt.ls launched, the client can send a Command to the server to start a debug session:

{
  "command": "vscode.java.startDebugSession"
}

So from my understanding i think i need to accomplish these three things? Correct me if im wrong.

1. Get nvim-metals to launch jdt.ls with the initialisation options to include the debug-java jar
2. Use nvim-metals to send a custom command vscode.java.startDebugSession to the launched jdt.ls in step 1. (This is to be done in the nvim-dap configuration for the dap.adapters.java?) The response to that command will tell me the port number to attach to.
3. Configure my nvim-dap for scala to use that adapter? (not sure how to do this too)

Thanks in advance!