Add 'docker-wait-any' script, use it to wait for containers to exit

Author: Joe LeVeque

files/build_templates/sonic_debian_extension.j2

@@ -163,6 +163,9 @@ sudo cp $IMAGE_CONFIGS/hostname/hostname-config.service  $FILESYSTEM_ROOT/etc/sy
 sudo LANG=C chroot $FILESYSTEM_ROOT systemctl enable hostname-config.service
 sudo cp $IMAGE_CONFIGS/hostname/hostname-config.sh $FILESYSTEM_ROOT/usr/bin/
 
+# Copy miscellaneous scripts
+sudo cp $IMAGE_CONFIGS/misc/docker-wait-any $FILESYSTEM_ROOT/usr/bin/
+
 # Copy updategraph script and service file
 j2 files/build_templates/updategraph.service.j2 | sudo tee $FILESYSTEM_ROOT/etc/systemd/system/updategraph.service
 sudo LANG=C chroot $FILESYSTEM_ROOT systemctl enable updategraph.service

files/build_templates/swss.service.j2

@@ -41,8 +41,7 @@ ExecStartPre=/etc/init.d/xpnet.sh start
 
 ExecStartPre=/usr/bin/{{docker_container_name}}.sh start 
 ExecStartPre=/usr/bin/syncd.sh start
-ExecStartPre=/usr/bin/{{docker_container_name}}.sh start
-ExecStart=/bin/bash -c "sleep 5; while true; do if [ x\"$(docker inspect -f {{'{{'}}.State.Running{{'}}'}} {{docker_container_name}})\" != x\"true\" ] || [ x\"$(docker inspect -f {{'{{'}}.State.Running{{'}}'}} syncd)\" != x\"true\" ]; then break; fi; sleep 1; done"
+ExecStart=/bin/bash -c "sleep 5; /usr/bin/docker-wait-any {{docker_container_name}} syncd"
 
 ExecStop=/usr/bin/{{docker_container_name}}.sh stop
 ExecStopPost=/usr/bin/syncd.sh stop

files/image_config/misc/docker-wait-any

@@ -0,0 +1,65 @@
+#!/usr/bin/env python
+
+"""
+    docker-wait-any
+
+    This script takes one or more Docker container names as arguments,
+    and it will block indefinitely while all of the specified containers
+    are running. If any of the specified containers stop, the script will
+    exit.
+
+    This script was created because the 'docker wait' command is lacking
+    this functionality. It will block until ALL specified containers have
+    stopped running. Here, we spawn multiple threads and wait on one
+    container per thread. If any of the threads exit, the entire
+    application will exit.
+
+    NOTE: This script is written against docker-py version 1.6.0. Newer
+    versions of docker-py have a different API.
+"""
+
+import sys
+import threading
+from docker import Client
+
+# Instantiate a global event to share among our threads
+g_thread_exit_event = threading.Event()
+
+
+def usage():
+    print("Usage: {} <container_name> [<container_name> ...]".format(sys.argv[0]))
+    sys.exit(1)
+
+
+def wait_for_container(docker_client, container_name):
+    docker_client.wait(container_name)
+
+    print("No longer waiting on container '{}'".format(container_name))
+
+    # Signal the main thread to exit
+    g_thread_exit_event.set()
+
+
+def main():
+    thread_list = []
+
+    docker_client = Client(base_url='unix://var/run/docker.sock')
+
+    # Ensure we were passed at least one argument
+    if len(sys.argv) < 2:
+        usage()
+
+    container_names = sys.argv[1:]
+
+    for container_name in container_names:
+        t = threading.Thread(target=wait_for_container, args=[docker_client, container_name])
+        t.daemon = True
+        t.start()
+        thread_list.append(t)
+
+    # Wait until we receive an event signifying one of the containers has stopped
+    g_thread_exit_event.wait()
+    sys.exit(0)
+
+if __name__ == '__main__':
+    main()