Start/stop the IPykernel process

Author: intentionally-left-nil

.vscode/settings.json

@@ -0,0 +1,3 @@
+{
+  "deno.enable": true
+}

packages/python-runtime-agent/deno.json

@@ -15,7 +15,8 @@
   },
   "imports": {
     "@runt/lib": "jsr:@runt/lib@^0.6.2",
-    "@runt/schema": "jsr:@runt/schema@^0.6.2"
+    "@runt/schema": "jsr:@runt/schema@^0.6.2",
+    "@std/path": "jsr:@std/path@^1.1.1"
   },
   "tasks": {
     "test": "deno test --allow-all",

packages/python-runtime-agent/src/python-runtime-agent.ts

@@ -1,10 +1,15 @@
 import {
+  createLogger,
   createRuntimeConfig,
   RuntimeAgent,
+  type RuntimeAgentOptions,
   type RuntimeConfig,
 } from "@runt/lib";
+import * as path from "@std/path";
 
 export class PythonRuntimeAgent extends RuntimeAgent {
+  private kernel: Deno.ChildProcess | null = null;
+  private logger = createLogger("python-runtime-agent");
   constructor(args: string[] = Deno.args) {
     let config: RuntimeConfig;
     try {
@@ -36,6 +41,54 @@ export class PythonRuntimeAgent extends RuntimeAgent {
       Deno.exit(1);
     }
 
-    super(config, config.capabilities, {});
+    super(config, config.capabilities, {
+      onStartup: (environmentOptions) => this.onStartup(environmentOptions),
+      onShutdown: () => this.onShutdown(),
+    });
+  }
+
+  private async onStartup(
+    options: RuntimeAgentOptions["environmentOptions"],
+  ): Promise<void> {
+    if (options.runtimeEnvExternallyManaged) {
+      const pythonPath = options.runtimePythonPath ?? "python3";
+      const tempDir = await Deno.makeTempDir({ prefix: "anode-kernel" });
+      const connPath = path.join(tempDir, "conn.json");
+      const args = ["-m", "ipykernel_launcher", "-f", connPath];
+      try {
+        const command = new Deno.Command(pythonPath, {
+          args,
+        });
+        this.logger.debug("Starting kernel", {
+          python: pythonPath,
+          args,
+        });
+        this.kernel = command.spawn();
+        this.logger.info("Kernel started", { pid: this.kernel.pid });
+      } finally {
+        Deno.removeSync(tempDir, { recursive: true });
+      }
+    } else {
+      throw new Error("Not yet implemented");
+    }
+  }
+
+  private async onShutdown(): Promise<void> {
+    if (this.kernel) {
+      this.logger.info("Shutting down kernel", { pid: this.kernel.pid });
+      try {
+        this.kernel.kill();
+        const status = (await this.kernel.status).code;
+        this.logger.info("Kernel shutdown", {
+          pid: this.kernel.pid,
+          status,
+        });
+      } catch (error) {
+        this.logger.error("Error shutting down kernel", {
+          pid: this.kernel.pid,
+          error: error instanceof Error ? error.message : String(error),
+        });
+      }
+    }
   }
 }