docs(amazonq): Add instructions for debugging flare lsps (#6455)

## Problem
It's painful to setup debugging with flare

## Solution
Add instructions to make it easy


---

- Treat all work as PUBLIC. Private `feature/x` branches will not be
squash-merged at release time.
- Your code changes must meet the guidelines in
[CONTRIBUTING.md](https://github.com/aws/aws-toolkit-vscode/blob/master/CONTRIBUTING.md#guidelines).
- License: I confirm that my contribution is made under the terms of the
Apache 2.0 license.

Author: jpinkney-aws

docs/lsp-debugging.md

@@ -0,0 +1,23 @@
+## Language Server Debugging
+
+1. Clone https://github.com/aws/language-servers.git and set it up in the same workspace as this project
+
+    e.g.
+
+    ```
+    /aws-toolkit-vscode
+    /toolkit
+    /core
+    /amazonq
+    /language-servers
+    ```
+
+2. Inside of the language-servers project run:
+    ```
+    npm install
+    npm run compile
+    npm run package
+    ```
+    to get the project setup
+3. Uncomment the `AWS_LANGUAGE_SERVER_OVERRIDE` variable in `amazonq/.vscode/launch.json` Extension configuration
+4. Use the `Launch LSP with Debugging` configuration and set breakpoints in VSCode or the language server

packages/amazonq/.vscode/launch.json

@@ -19,6 +19,7 @@
             "env": {
                 "SSMDOCUMENT_LANGUAGESERVER_PORT": "6010",
                 "WEBPACK_DEVELOPER_SERVER": "http://localhost:8080"
+                // "AWS_LANGUAGE_SERVER_OVERRIDE": "${workspaceFolder}/../../../language-servers/app/aws-lsp-codewhisperer-runtimes/out/token-standalone.js",
             },
             "envFile": "${workspaceFolder}/.local.env",
             "outFiles": ["${workspaceFolder}/dist/**/*.js", "${workspaceFolder}/../core/dist/**/*.js"],
@@ -140,6 +141,31 @@
                 "group": "4_E2ETestCurrentFile",
                 "order": 2
             }
+        },
+        {
+            "name": "Attach to Language Server",
+            "type": "node",
+            "request": "attach",
+            "port": 6080, // Hard defined in core/src/shared/lsp/platform.ts
+            "outFiles": ["${workspaceFolder}/../../../language-servers/**/out/**/*.js"],
+            "skipFiles": [
+                "<node_internals>/**",
+                "${workspaceFolder}/../../../language-servers/**/node_modules/**/*.js"
+            ],
+            "restart": {
+                "maxAttempts": 10,
+                "delay": 1000
+            }
+        }
+    ],
+    "compounds": [
+        {
+            "name": "Launch LSP with Debugging",
+            "configurations": ["Extension", "Attach to Language Server"],
+            "presentation": {
+                "group": "1_Extension",
+                "order": 5
+            }
         }
     ]
 }

packages/amazonq/src/lsp/client.ts

@@ -6,7 +6,7 @@
 import vscode, { env, version } from 'vscode'
 import * as nls from 'vscode-nls'
 import * as crypto from 'crypto'
-import { LanguageClient, LanguageClientOptions, ServerOptions, TransportKind } from 'vscode-languageclient'
+import { LanguageClient, LanguageClientOptions } from 'vscode-languageclient'
 import { registerInlineCompletion } from '../app/inline/completion'
 import { AmazonQLspAuth, encryptionKey, notificationTypes } from './auth'
 import { AuthUtil } from 'aws-core-vscode/codewhisperer'
@@ -18,32 +18,19 @@ const localize = nls.loadMessageBundle()
 export async function startLanguageServer(extensionContext: vscode.ExtensionContext, resourcePaths: ResourcePaths) {
     const toDispose = extensionContext.subscriptions
 
-    // The debug options for the server
-    // --inspect=6009: runs the server in Node's Inspector mode so VS Code can attach to the server for debugging
-    const debugOptions = {
+    const serverModule = resourcePaths.lsp
+
+    const serverOptions = createServerOptions({
+        encryptionKey,
+        executable: resourcePaths.node,
+        serverModule,
         execArgv: [
             '--nolazy',
             '--preserve-symlinks',
             '--stdio',
             '--pre-init-encryption',
             '--set-credentials-encryption-key',
         ],
-    }
-
-    const serverModule = resourcePaths.lsp
-
-    // If the extension is launch in debug mode the debug server options are use
-    // Otherwise the run options are used
-    let serverOptions: ServerOptions = {
-        run: { module: serverModule, transport: TransportKind.ipc },
-        debug: { module: serverModule, transport: TransportKind.ipc, options: debugOptions },
-    }
-
-    serverOptions = createServerOptions({
-        encryptionKey,
-        executable: resourcePaths.node,
-        serverModule,
-        execArgv: debugOptions.execArgv,
     })
 
     const documentSelector = [{ scheme: 'file', language: '*' }]

packages/core/src/shared/lsp/utils/platform.ts

@@ -5,6 +5,7 @@
 
 import { ToolkitError } from '../../errors'
 import { ChildProcess } from '../../utilities/processUtils'
+import { isDebugInstance } from '../../vscode/env'
 
 export function getNodeExecutableName(): string {
     return process.platform === 'win32' ? 'node.exe' : 'node'
@@ -35,7 +36,8 @@ export function createServerOptions({
     execArgv: string[]
 }) {
     return async () => {
-        const lspProcess = new ChildProcess(executable, [serverModule, ...execArgv])
+        const debugArgs = isDebugInstance() ? '--inspect=6080' : ''
+        const lspProcess = new ChildProcess(executable, [debugArgs, serverModule, ...execArgv])
 
         // this is a long running process, awaiting it will never resolve
         void lspProcess.run()