Add exec heartbeat keepalive (#8759)

This closes #8727, thanks to @jfcantu for the suggestion.
The CLI implementation of exec already has a 10-second
heartbeat so this mirrors that:
https://github.com/hashicorp/nomad/blob/v0.12.3/api/allocations.go#L161-L173

CHANGELOG.md

@@ -5,6 +5,7 @@ IMPROVEMENTS:
  * api: Added node purge SDK functionality. [[GH-8142](https://github.com/hashicorp/nomad/issues/8142)]
  * csi: Improved the accuracy of plugin `Expected` allocation counts. [[GH-8699](https://github.com/hashicorp/nomad/pull/8699)]
  * driver/docker: Allow configurable image pull context timeout setting. [[GH-5718](https://github.com/hashicorp/nomad/issues/5718)]
+ * ui: Added exec keepalive heartbeat. [[GH-8759](https://github.com/hashicorp/nomad/pull/8759)]
 
 BUG FIXES:
 

ui/app/utils/classes/exec-socket-xterm-adapter.js

@@ -3,6 +3,8 @@ const ANSI_UI_GRAY_400 = '\x1b[38;2;142;150;163m';
 import base64js from 'base64-js';
 import { TextDecoderLite, TextEncoderLite } from 'text-encoder-lite';
 
+export const HEARTBEAT_INTERVAL = 10000; // ten seconds
+
 export default class ExecSocketXtermAdapter {
   constructor(terminal, socket, token) {
     this.terminal = terminal;
@@ -12,6 +14,7 @@ export default class ExecSocketXtermAdapter {
     socket.onopen = () => {
       this.sendWsHandshake();
       this.sendTtySize();
+      this.startHeartbeat();
 
       terminal.onData(data => {
         this.handleData(data);
@@ -28,6 +31,7 @@ export default class ExecSocketXtermAdapter {
     };
 
     socket.onclose = () => {
+      this.stopHeartbeat();
       this.terminal.writeln('');
       this.terminal.write(ANSI_UI_GRAY_400);
       this.terminal.writeln('The connection has closed.');
@@ -49,6 +53,16 @@ export default class ExecSocketXtermAdapter {
     this.socket.send(JSON.stringify({ version: 1, auth_token: this.token || '' }));
   }
 
+  startHeartbeat() {
+    this.heartbeatTimer = setInterval(() => {
+      this.socket.send(JSON.stringify({}));
+    }, HEARTBEAT_INTERVAL);
+  }
+
+  stopHeartbeat() {
+    clearInterval(this.heartbeatTimer);
+  }
+
   handleData(data) {
     this.socket.send(JSON.stringify({ stdin: { data: encodeString(data) } }));
   }

ui/tests/integration/util/exec-socket-xterm-adapter-test.js

@@ -4,6 +4,8 @@ import { module, test } from 'qunit';
 import { render, settled } from '@ember/test-helpers';
 import hbs from 'htmlbars-inline-precompile';
 import { Terminal } from 'xterm';
+import { HEARTBEAT_INTERVAL } from 'nomad-ui/utils/classes/exec-socket-xterm-adapter';
+import sinon from 'sinon';
 
 module('Integration | Utility | exec-socket-xterm-adapter', function(hooks) {
   setupRenderingTest(hooks);
@@ -26,6 +28,7 @@ module('Integration | Utility | exec-socket-xterm-adapter', function(hooks) {
         if (firstMessage) {
           firstMessage = false;
           assert.deepEqual(message, JSON.stringify({ version: 1, auth_token: 'mysecrettoken' }));
+          mockSocket.onclose();
           done();
         }
       },
@@ -56,6 +59,7 @@ module('Integration | Utility | exec-socket-xterm-adapter', function(hooks) {
         if (firstMessage) {
           firstMessage = false;
           assert.deepEqual(message, JSON.stringify({ version: 1, auth_token: '' }));
+          mockSocket.onclose();
           done();
         }
       },
@@ -68,6 +72,40 @@ module('Integration | Utility | exec-socket-xterm-adapter', function(hooks) {
     await settled();
   });
 
+  test('a heartbeat is sent periodically', async function(assert) {
+    let done = assert.async();
+
+    const clock = sinon.useFakeTimers({
+      now: new Date(),
+      shouldAdvanceTime: true,
+    });
+
+    let terminal = new Terminal();
+    this.set('terminal', terminal);
+
+    await render(hbs`
+      <ExecTerminal @terminal={{terminal}} />
+    `);
+
+    await settled();
+
+    let mockSocket = new Object({
+      send(message) {
+        if (!message.includes('version') && !message.includes('tty_size')) {
+          assert.deepEqual(message, JSON.stringify({}));
+          clock.restore();
+          mockSocket.onclose();
+          done();
+        }
+      },
+    });
+
+    new ExecSocketXtermAdapter(terminal, mockSocket, null);
+    mockSocket.onopen();
+    await settled();
+    clock.tick(HEARTBEAT_INTERVAL);
+  });
+
   test('resizing the window passes a resize message through the socket', async function(assert) {
     let done = assert.async();
 
@@ -86,6 +124,7 @@ module('Integration | Utility | exec-socket-xterm-adapter', function(hooks) {
           message,
           JSON.stringify({ tty_size: { width: terminal.cols, height: terminal.rows } })
         );
+        mockSocket.onclose();
         done();
       },
     });
@@ -120,6 +159,7 @@ module('Integration | Utility | exec-socket-xterm-adapter', function(hooks) {
     });
 
     await settled();
+    mockSocket.onclose();
   });
 
   test('stderr frames are ignored', async function(assert) {
@@ -155,5 +195,7 @@ module('Integration | Utility | exec-socket-xterm-adapter', function(hooks) {
         .trim(),
       'sh-3.2 🥳$'
     );
+
+    mockSocket.onclose();
   });
 });