wait_for: Added script to wait for a service to come up

wait_for.py

@@ -0,0 +1,60 @@
+#!/usr/bin/env python
+import argparse
+import socket
+import time
+import os
+import signal
+
+
+def parse_args():
+    parser = argparse.ArgumentParser()
+    parser.add_argument(
+        '--timeout', '-t',
+        type=int,
+        metavar='SECONDS',
+        help='Number of seconds to wait for host',
+    )
+    parser.add_argument(
+        'host',
+        help='Remote host name',
+    )
+    parser.add_argument(
+        'service',
+        nargs='?',
+        default='ssh',
+        help='Service/port on remote host',
+    )
+    return parser.parse_args()
+
+
+def wait_for(host, service, timeout=None):
+    if timeout:
+        deadline = time.time() + timeout
+    else:
+        deadline = None
+    while True:
+        try:
+            sock = socket.create_connection((host, service))
+        except socket.error:
+            if deadline and time.time() >= deadline:
+                break
+            time.sleep(1)
+        else:
+            sock.close()
+            return True
+    return False
+
+
+def main():
+    args = parse_args()
+
+    try:
+        if not wait_for(args.host, args.service, args.timeout):
+            raise SystemExit(1)
+    except KeyboardInterrupt:
+        signal.signal(signal.SIGINT, signal.SIG_DFL)
+        os.kill(os.getpid(), signal.SIGINT)
+
+
+if __name__ == '__main__':
+    main()