Major refactor to separate out and standardize libraries

daemon-common/daemon_lib/zkhandler.py

@@ -0,0 +1,60 @@
+#!/usr/bin/env python3
+
+# zkhandler.py - Secure versioned ZooKeeper updates
+# Part of the Parallel Virtual Cluster (PVC) system
+#
+#    Copyright (C) 2018  Joshua M. Boniface <joshua@boniface.me>
+#
+#    This program is free software: you can redistribute it and/or modify
+#    it under the terms of the GNU General Public License as published by
+#    the Free Software Foundation, either version 3 of the License, or
+#    (at your option) any later version.
+#
+#    This program is distributed in the hope that it will be useful,
+#    but WITHOUT ANY WARRANTY; without even the implied warranty of
+#    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+#    GNU General Public License for more details.
+#
+#    You should have received a copy of the GNU General Public License
+#    along with this program.  If not, see <https://www.gnu.org/licenses/>.
+#
+###############################################################################
+
+import kazoo.client
+import daemon_lib.ansiiprint as ansiiprint
+
+# Child list function
+def listchildren(zk_conn, key):
+    children = zk_conn.get_children(key)
+    return children
+
+# Data read function
+def readdata(zk_conn, key):
+    data_raw = zk_conn.get(key)
+    data = data_raw[0].decode('ascii')
+    meta = data_raw[1]
+    return data
+
+# Data write function
+def writedata(zk_conn, kv):
+    # Get the current version; we base this off the first key (ordering in multi-key calls is irrelevant)
+    first_key = list(kv.keys())[0]
+    orig_data_raw = zk_conn.get(first_key)
+    meta = orig_data_raw[1]
+    if meta == None:
+        ansiiprint.echo('Zookeeper key "{}" does not exist'.format(first_key), '', 'e')
+        return 1
+
+    version = meta.version
+    new_version = version + 1
+    zk_transaction = zk_conn.transaction()
+    for key, data in kv.items():
+        zk_transaction.set_data(key, data.encode('ascii'))
+    try:
+        zk_transaction.check(first_key, new_version)
+    except TypeError:
+        ansiiprint.echo('Zookeeper key "{}" does not match expected version'.format(first_key), '', 'e')
+        return 1
+    zk_transaction.commit()
+    return 0
+