First step towards a new, improved cumulus front-end.

[cumulus.git] / python / cumulus / config.py

diff --git a/python/cumulus/config.py b/python/cumulus/config.py
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+# Cumulus: Smart Filesystem Backup to Dumb Servers
+#
+# Copyright (C) 2012  Google Inc.
+# Written by Michael Vrable <mvrable@cs.ucsd.edu>
+#
+# 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 2 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, write to the Free Software Foundation, Inc.,
+# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+
+"""Parsing of Cumulus backup configuration files.
+
+See the Cumulus documentation for a description of the configuration file
+format.
+"""
+
+import ConfigParser
+import datetime
+import re
+
+from cumulus import retention
+
+_BACKUP_PREFIX = "backup:"
+_TIME_UNITS = {"s": 1, "m": 60, "h": 3600, "D": 86400, "W": 7 * 86400,
+               "M": 30 * 86400, "Y": 365 * 86400}
+_INTERVAL_RE = r"(\d+)([smhDWMY])"
+
+def _build_retention_engine(spec):
+    """Parse a retention specification and return a RetentionEngine object."""
+    policy = retention.RetentionEngine()
+    class_re = re.compile(r"^(\w+):((%s)+)$" % _INTERVAL_RE)
+    interval_re = re.compile(r"^%s(.*)$" % _INTERVAL_RE)
+    for s in spec.split():
+        m = class_re.match(s)
+        if not m:
+            print "Invalid retain spec:", s
+            continue
+        period = datetime.timedelta()
+        classname = m.group(1)
+        intervalspec = m.group(2)
+        while intervalspec:
+            m = interval_re.match(intervalspec)
+            seconds = int(m.group(1)) * _TIME_UNITS[m.group(2)]
+            period = period + datetime.timedelta(seconds=seconds)
+            intervalspec = m.group(3)
+        print classname, period
+        policy.add_policy(classname, period)
+    return policy
+
+
+class CumulusConfig(object):
+    def __init__(self, filename):
+        """Parse a Cumulus backup configuration from the specified file."""
+        self._config = ConfigParser.RawConfigParser()
+        self._config.readfp(open(filename))
+
+    def get_global(self, key):
+        return self._config.get("global", key)
+
+    def backup_schemes(self):
+        """Returns a list of backup schemes."""
+        return [s[len(_BACKUP_PREFIX):] for s in self._config.sections()
+                if s.startswith(_BACKUP_PREFIX)]
+
+    def get_retention_for_scheme(self, scheme):
+        spec = self._config.get(_BACKUP_PREFIX + scheme, "retain")
+        return _build_retention_engine(spec)