Add a device to mount the host /dev/shm inside the container.

config.yml

@@ -7,6 +7,8 @@ defaults:
       enabled: true
     loopbackVideo:
       enabled: true
+    hostSharedMemory:
+      enabled: true
   phone:
     enabled: false
     sims: '1'

schemas/v1/payload.json

@@ -146,6 +146,11 @@
               "title": "Loopback Audio device",
               "description": "Audio loopback device created using snd-aloop",
               "type": "boolean"
+            },
+            "hostSharedMemory": {
+              "title": "Host shared memory device (Experimental)",
+              "description": "Mount /dev/shm from the host in the container.",
+              "type": "boolean"
             }
           }
         }

src/lib/devices/device_manager.js

@@ -3,13 +3,15 @@ const Debug = require('debug');
 const VideoDeviceManager = require('./video_device_manager');
 const AudioDeviceManager = require('./audio_device_manager');
 const CpuDeviceManager = require('./cpu_device_manager');
+const SharedMemoryDeviceManager = require('./shared_memory_device_manager');
 
 let debug = Debug('taskcluster-docker-worker:deviceManager');
 
 const DEVICE_MANAGERS = {
   'loopbackVideo': VideoDeviceManager,
   'loopbackAudio': AudioDeviceManager,
   'cpu': CpuDeviceManager,
+  'hostSharedMemory': SharedMemoryDeviceManager
 };
 
 
@@ -42,6 +44,9 @@ class DeviceManager {
 
   async getAvailableCapacity() {
     let devices = await Promise.all(Object.keys(this.managers).map(async (manager) => {
+      if (this.managers[manager].unlimitedDevices) {
+        return Infinity;
+      }
       let availableDevices = await this.managers[manager].getAvailableDevices();
       return availableDevices.length;
     }));

src/lib/devices/shared_memory_device_manager.js

@@ -0,0 +1,41 @@
+const Debug = require('debug');
+
+let debug = Debug('taskcluster-docker-worker:devices:sharedMemoryManager');
+
+class SharedMemoryDeviceManager {
+  constructor() {
+    this.devices = [new SharedMemoryDevice()];
+    this.unlimitedDevices = true;
+  }
+
+  getAvailableDevice() {
+    let devices = this.getAvailableDevices();
+    let device = devices[0];
+    device.acquire();
+
+    debug(`Device: ${device.path} acquired`);
+
+    return device;
+  }
+
+  getAvailableDevices() {
+    return this.devices;
+  }
+}
+
+class SharedMemoryDevice {
+  constructor() {
+    this.mountPoints = [
+      '/dev/shm'
+    ];
+  }
+
+  acquire() {}
+
+  release() {
+    debug('Device: /dev/shm released');
+  }
+
+}
+
+module.exports = SharedMemoryDeviceManager;

test/integration/device_link_test.js

@@ -174,4 +174,34 @@ suite('device linking within containers', () => {
       `Worker should just capacity based on the number of devices that could be found:\n${message}`
     );
   });
+
+  test.skip('/dev/shm is shared with the host', async () => {
+    worker = new TestWorker(DockerWorker);
+    await worker.launch();
+    let task = {
+      scopes: ['docker-worker:capability:device:hostSharedMemory'],
+      payload: {
+        capabilities: {
+          devices: {
+            hostSharedMemory: true
+          }
+        },
+        image: 'ubuntu:14.10',
+        command: cmd(
+          'mount | grep dev/shm',
+          'mount | grep dev/shm | grep -vq size= || { echo \'/dev/shm should not contain size\'; exit 1; }'
+        ),
+        maxRunTime: 5 * 60
+      }
+    };
+
+    let result = await worker.postToQueue(task);
+
+    assert.equal(result.status.state, 'completed', 'Task state is not marked as completed');
+    assert.equal(
+      result.run.reasonResolved,
+      'completed',
+      'Task not resolved as complete'
+    );
+  });
 });