hostsdns: add support for command line args

Add ability for event-watcher.py to run in host-only
mode and to run without continuous polling.

Change-Id: Idd08a2bc1849af37c2c0e82ee1ef7b1e9c4c2e0c

1 files changed, 12 insertions, 6 deletions

diff --git a/hostsdns/event-watcher.py b/hostsdns/event-watcher.py
index b51ec76..3446777 100755
--- a/hostsdns/event-watcher.py
+++ b/hostsdns/event-watcher.py
@@ -1,16 +1,19 @@
 #!/usr/bin/env python
 
-import os
-import sys
+import os, sys, json, re
 import docker
-import json
-import re
+import argparse
 
-if os.path.exists("/.dockerenv"):
+parser = argparse.ArgumentParser( description="Manage host entries for docker containers")
+parser.add_argument('-n', '--native', help='run service on docker host', action='store_true' , dest='NATIVE_MODE')
+parser.add_argument('-o','-1', '--once', help='run once and exit (no continuous polling)', action='store_true', dest='ONCE_MODE')
+args = parser.parse_args()
+
+if not args.NATIVE_MODE and os.path.exists("/.dockerenv"):
     print "Found /.dockerenv... reading from /tmp/hosts"
     HOSTS_FILE="/tmp/hosts"
 else:
-    print "No /.dockerenv found... reading from /etc/hosts"
+    print "Running in native mode... reading from /etc/hosts"
     HOSTS_FILE="/etc/hosts"
 
 if os.environ.get("DOCKER_HOST"):
@@ -93,6 +96,9 @@ def container_remove(name):
 for container in client.containers.list():
     container_add(container.name)
 
+if args.ONCE_MODE:
+    sys.exit(0)
+
 # calling events will basically poll forever, so after this we're
 #  essentially in not-quite-a-daemon mode
 for event_json in client.events():