Run oom_detector within host network

Since we extended oom_detector to send heartbeat when there is
significant network traffic, we need to expose the host network so it
can check the network IO from other containers

cloud/google/workers.py

@@ -88,7 +88,7 @@ def GenerateWorkers(context, hostname_manager, hostname_nfs_server, worker):
 
     docker_image = worker.get('workerImage', context.properties['seuronImage'])
 
-    oom_canary_cmd = GenerateDockerCommand(docker_image, docker_env) + ' ' + "python utils/memory_monitor.py ${AIRFLOW__CELERY__BROKER_URL} bot-message-queue >& /dev/null"
+    oom_canary_cmd = GenerateDockerCommand(docker_image, docker_env + ['--network host']) + ' ' + "python utils/memory_monitor.py ${AIRFLOW__CELERY__BROKER_URL} bot-message-queue >& /dev/null"
 
     if worker['type'] == 'gpu':
         cmd = GenerateCeleryWorkerCommand(docker_image, docker_env+['-p 8793:8793'], queue=worker['type'], concurrency=worker['concurrency'])