fix: app subprocess restart on error and better reporting

packages/apps-engine/deno-runtime/handlers/app/handler.ts

@@ -21,7 +21,23 @@ export default async function handleApp(method: string, params: unknown): Promis
 
     // We don't want the getStatus method to generate logs, so we handle it separately
     if (appMethod === 'getStatus') {
-        return handleGetStatus();
+        try {
+            return handleGetStatus();
+        } catch (e) {
+            if (!(e instanceof Error)) {
+                return new JsonRpcError('Unknown error', -32000, e);
+            }
+
+            if ((e.cause as string)?.includes('invalid_param_type')) {
+                return JsonRpcError.invalidParams(null);
+            }
+
+            if ((e.cause as string)?.includes('invalid_app')) {
+                return JsonRpcError.internalError({ message: 'App unavailable' });
+            }
+
+            return new JsonRpcError(e.message, -32000, e);
+        }
     }
 
     // `app` will be undefined if the method here is "app:construct"

packages/apps-engine/src/server/runtime/deno/AppsEngineDenoRuntime.ts

@@ -318,18 +318,21 @@ export class DenoRuntimeSubprocessController extends EventEmitter {
     }
 
     private waitUntilReady(): Promise<void> {
+        if (this.state === 'ready') {
+            return;
+        }
         return new Promise((resolve, reject) => {
-            const timeoutId = setTimeout(() => reject(new Error(`[${this.getAppId()}] Timeout: app process not ready`)), this.options.timeout);
-
-            if (this.state === 'ready') {
+            let timeoutId: NodeJS.Timeout;
+            const handler = () => {
                 clearTimeout(timeoutId);
-                return resolve();
-            }
+                resolve();
+            };
+            timeoutId = setTimeout(() => {
+                this.off('ready', handler);
+                reject(new Error(`[${this.getAppId()}] Timeout: app process not ready`));
+            }, this.options.timeout);
 
-            this.once('ready', () => {
-                clearTimeout(timeoutId);
-                return resolve();
-            });
+            this.once('ready', handler);
         });
     }
 

packages/apps-engine/src/server/runtime/deno/LivenessManager.ts

@@ -82,6 +82,7 @@ export class LivenessManager {
 
         this.controller.once('ready', () => this.ping());
         this.subprocess.once('exit', this.handleExit.bind(this));
+        this.subprocess.once('error', this.handleError.bind(this));
     }
 
     /**
@@ -155,6 +156,11 @@ export class LivenessManager {
         this.messenger.send(COMMAND_PING);
     }
 
+    private handleError(err: Error) {
+        this.debug('App has failed to start.`', err);
+        this.restartProcess(err.message);
+    }
+
     private handleExit(exitCode: number, signal: string) {
         this.pingAbortController.emit('abort');
 
@@ -194,6 +200,6 @@ export class LivenessManager {
             pid: this.subprocess.pid,
         });
 
-        this.controller.restartApp();
+        setTimeout(() => this.controller.restartApp(), Math.max(this.restartCount++ * 1000, 10 * 1000));
     }
 }