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# Copyright 2012, 2013 Canonical Ltd. This software is licensed under the
# GNU Affero General Public License version 3 (see the file LICENSE).
"""Migrate data for the mongodb instance.
Loads migrations from the latest available in the versions directory.
"""
import argparse
from datetime import datetime
import imp
from os import listdir
from os.path import abspath
from os.path import dirname
from os.path import join
import re
from charmworld.models import getconnection
from charmworld.models import getdb
from charmworld.search import ElasticSearchClient
from charmworld.utils import get_ini
SCRIPT_TEMPLATE = """
# {description}
def upgrade(db):
\"\"\"Complete this function with work to be done for the migration/update.
db is the pymongo db instance for our datastore. Charms are in db.charms
for instance.
\"\"\"
"""
def str_to_filename(s):
"""Replaces spaces, quotes, and double underscores to underscores."""
s = s.replace(' ', '_')\
.replace('"', '_')\
.replace("'", '_')\
.replace(".", "_")
while '__' in s:
s = s.replace('__', '_')
return s
class DataStore(object):
"""Communicate with the data store to determine version status."""
def __init__(self, db):
"""Talk to the data store
:param db: The mongo db connection.
"""
self.db = db
@property
def current_version(self):
"""Return the current version of the data store."""
found = self.db.migration_version.find_one({
'_id': 'version'
})
if found:
return found['version']
else:
return None
def update_version(self, version):
"""Update the version number in the data store."""
self.db.migration_version.save({
'_id': 'version',
'version': version,
'date': datetime.now(),
})
def version_datastore(self):
"""Init the data to track the current version in the datastore.
The data store starts out with version 0.
Raises exception if the store is already versioned.
"""
if self.current_version is not None:
raise Exception('Data store is already versioned: {0}'.format(
self.current_version))
self.db.migration_version.insert({
'_id': 'version',
'version': 0,
'date': datetime.now(),
})
class Versions(object):
def __init__(self, path):
"""Collect version scripts and store them in self.versions
"""
FILENAME_WITH_VERSION = re.compile(r'^(\d{3,}).*')
self.versions_dir = path
# Create temporary list of files, allowing skipped version numbers.
files = listdir(path)
versions = {}
for name in files:
if not name.endswith('.py'):
# Skip .pyc and the like
continue
match = FILENAME_WITH_VERSION.match(name)
if match:
num = int(match.group(1))
versions[num] = name
else:
pass # Must be a helper file or something, let's ignore it.
self.versions = {}
version_numbers = versions.keys()
version_numbers.sort()
self.version_indexes = version_numbers
for idx in version_numbers:
self.versions[idx] = versions[idx]
def create_new_version_file(self, description):
"""Create Python files for new version"""
version = self.latest + 1
if not description:
raise ValueError('Please provide a short migration description.')
filename = "{0}_{1}.py".format(
str(version).zfill(3),
str_to_filename(description)
)
filepath = join(self.versions_dir, filename)
with open(filepath, 'w') as new_migration:
new_migration.write(
SCRIPT_TEMPLATE.format(description=description))
# Update our current store of version data.
self.versions[version] = filename
self.version_indexes.append(version)
return filename
@property
def latest(self):
""":returns: Latest version in Collection"""
return self.version_indexes[-1] if len(self.version_indexes) > 0 else 0
def run_migration(self, db, index_client, module_name):
module = imp.load_source(
module_name.strip('.py'),
join(self.versions_dir, module_name))
getattr(module, 'upgrade')(db, index_client)
def upgrade(self, datastore, index_client, init):
"""Run `upgrade` methods for required version files.
:param datastore: An instance of DataStore
"""
current_version = datastore.current_version
if current_version is None:
if init:
# We want to auto init the database anyway.
datastore.version_datastore()
current_version = 0
else:
raise Exception('Data store is not versioned')
if current_version >= self.latest:
# Nothing to do here. All migrations processed already.
return None
while current_version < self.latest:
# Let's get processing.
next_version = current_version + 1
module_name = self.versions[next_version]
self.run_migration(datastore.db, index_client, module_name)
current_version = next_version
datastore.update_version(current_version)
return current_version
def parse_args():
desc = "Mongo migration tool."
parser = argparse.ArgumentParser(description=desc)
subparsers = parser.add_subparsers(help='sub-command help')
parser_current = subparsers.add_parser('current')
parser_current.set_defaults(func=Commands.current)
parser_latest = subparsers.add_parser('latest')
parser_latest.set_defaults(func=Commands.latest)
parser_new = subparsers.add_parser('new')
parser_new.add_argument(
'-d', '--description', action='store',
required=True,
help='The description of the new migration.')
parser_new.set_defaults(func=Commands.new)
parser_upgrade = subparsers.add_parser('upgrade')
parser_upgrade.set_defaults(func=Commands.upgrade)
parser_upgrade.add_argument(
'-i', '--init', action='store_true',
default=False,
help='Auto init the database if not already init.')
args = parser.parse_args()
return args
class Commands(object):
"""Container for the various commands the cli can execute"""
@staticmethod
def get_datastore(ini):
connection = getconnection(ini)
db = getdb(connection, ini.get('mongo.database'))
ds = DataStore(db)
return ds
@classmethod
def current(cls, ini, args):
"""Fetch the current migration version of the data store."""
ds = cls.get_datastore(ini)
version = ds.current_version
if version is None:
print 'Data store is not currently versioned.'
else:
print version
@staticmethod
def latest(ini, args):
"""Determine the latest migration version available."""
migrations = Versions(ini['migrations'])
print migrations.latest
@staticmethod
def new(ini, args):
"""Generate a new migration file to be completed."""
migrations = Versions(ini['migrations'])
filename = migrations.create_new_version_file(args.description)
print "Created new migration: {0}".format(filename)
@classmethod
def upgrade(cls, ini, args):
"""Upgrade the data store to the latest available migration."""
ds = cls.get_datastore(ini)
index_client = ElasticSearchClient.from_settings(ini)
migrations = Versions(ini['migrations'])
new_version = migrations.upgrade(ds, index_client, args.init)
if new_version is None:
print 'There are no new migrations to apply'
else:
print "Updated the datastore to version: {0}".format(new_version)
def main():
"""Target for the console entry point."""
args = parse_args()
ini = get_ini()
# Add the migration path to the ini.
migration_path = join(abspath(dirname(__file__)), 'versions')
ini['migrations'] = migration_path
args.func(ini, args)
if __name__ == '__main__':
main()
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