Add a helper tool which clears zookeeper test dirs

Create a tool that can clear any leftover garbage left
by the testing of taskflow unit tests with zookeeper for
when this is needed (for example, a test does not clean up
correctly on its own).

Change-Id: Icfaf28273b76a6ca27683d174f111fba2858f055

tools/clear_zk.py

@@ -0,0 +1,50 @@
+#!/usr/bin/env python
+
+import contextlib
+import os
+import re
+import sys
+
+top_dir = os.path.abspath(os.path.join(os.path.dirname(__file__),
+                                       os.pardir))
+sys.path.insert(0, top_dir)
+
+from taskflow.utils import kazoo_utils
+
+
+@contextlib.contextmanager
+def finalize_client(client):
+    try:
+        yield client
+    finally:
+        kazoo_utils.finalize_client(client)
+
+
+def iter_children(client, path):
+    if client.exists(path):
+        for child_path in client.get_children(path):
+            if path == "/":
+                child_path = "/%s" % (child_path)
+            else:
+                child_path = "%s/%s" % (path, child_path)
+            yield child_path
+            for child_child_path in iter_children(client, child_path):
+                yield child_child_path
+
+
+def main():
+    conf = {}
+    if len(sys.argv) > 1:
+        conf['hosts'] = sys.argv[1:]
+    with finalize_client(kazoo_utils.make_client(conf)) as client:
+        client.start(timeout=1.0)
+        children = list(iter_children(client, "/taskflow"))
+        for child_path in reversed(children):
+            if not re.match(r"^/taskflow/(.*?)-test/(.*)$", child_path):
+                continue
+            print("Deleting %s" % child_path)
+            client.delete(child_path)
+
+
+if __name__ == "__main__":
+    main()