OpenStack Compute (Nova)
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#!/usr/bin/env python
# Copyright 2012 OpenStack Foundation
#
# Licensed under the Apache License, Version 2.0 (the "License"); you may
# not use this file except in compliance with the License. You may obtain
# a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
# License for the specific language governing permissions and limitations
# under the License.
"""
Utility for diff'ing two versions of the DB schema.
Each release cycle the plan is to compact all of the migrations from that
release into a single file. This is a manual and, unfortunately, error-prone
process. To ensure that the schema doesn't change, this tool can be used to
diff the compacted DB schema to the original, uncompacted form.
The database is specified by providing a SQLAlchemy connection URL WITHOUT the
database-name portion (that will be filled in automatically with a temporary
database name).
The schema versions are specified by providing a git ref (a branch name or
commit hash) and a SQLAlchemy-Migrate version number:
Run like:
MYSQL:
./tools/db/schema_diff.py mysql+pymysql://root@localhost \
master:latest my_branch:82
POSTGRESQL:
./tools/db/schema_diff.py postgresql://localhost \
master:latest my_branch:82
"""
import datetime
import glob
import os
import subprocess
import sys
from nova.i18n import _
# Dump
def dump_db(db_driver, db_name, db_url, migration_version, dump_filename):
if not db_url.endswith('/'):
db_url += '/'
db_url += db_name
db_driver.create(db_name)
try:
_migrate(db_url, migration_version)
db_driver.dump(db_name, dump_filename)
finally:
db_driver.drop(db_name)
# Diff
def diff_files(filename1, filename2):
pipeline = ['diff -U 3 %(filename1)s %(filename2)s'
% {'filename1': filename1, 'filename2': filename2}]
# Use colordiff if available
if subprocess.call(['which', 'colordiff']) == 0:
pipeline.append('colordiff')
pipeline.append('less -R')
cmd = ' | '.join(pipeline)
subprocess.check_call(cmd, shell=True)
# Database
class Mysql(object):
def create(self, name):
subprocess.check_call(['mysqladmin', '-u', 'root', 'create', name])
def drop(self, name):
subprocess.check_call(['mysqladmin', '-f', '-u', 'root', 'drop', name])
def dump(self, name, dump_filename):
subprocess.check_call(
'mysqldump -u root %(name)s > %(dump_filename)s'
% {'name': name, 'dump_filename': dump_filename},
shell=True)
class Postgresql(object):
def create(self, name):
subprocess.check_call(['createdb', name])
def drop(self, name):
subprocess.check_call(['dropdb', name])
def dump(self, name, dump_filename):
subprocess.check_call(
'pg_dump %(name)s > %(dump_filename)s'
% {'name': name, 'dump_filename': dump_filename},
shell=True)
def _get_db_driver_class(db_url):
try:
return globals()[db_url.split('://')[0].capitalize()]
except KeyError:
raise Exception(_("database %s not supported") % db_url)
# Migrate
MIGRATE_REPO = os.path.join(os.getcwd(), "nova/db/sqlalchemy/migrate_repo")
def _migrate(db_url, migration_version):
earliest_version = _migrate_get_earliest_version()
# NOTE(sirp): sqlalchemy-migrate currently cannot handle the skipping of
# migration numbers.
_migrate_cmd(
db_url, 'version_control', str(earliest_version - 1))
upgrade_cmd = ['upgrade']
if migration_version != 'latest':
upgrade_cmd.append(str(migration_version))
_migrate_cmd(db_url, *upgrade_cmd)
def _migrate_cmd(db_url, *cmd):
manage_py = os.path.join(MIGRATE_REPO, 'manage.py')
args = ['python', manage_py]
args += cmd
args += ['--repository=%s' % MIGRATE_REPO,
'--url=%s' % db_url]
subprocess.check_call(args)
def _migrate_get_earliest_version():
versions_glob = os.path.join(MIGRATE_REPO, 'versions', '???_*.py')
versions = []
for path in glob.iglob(versions_glob):
filename = os.path.basename(path)
prefix = filename.split('_', 1)[0]
try:
version = int(prefix)
except ValueError:
pass
versions.append(version)
versions.sort()
return versions[0]
# Git
def git_current_branch_name():
ref_name = git_symbolic_ref('HEAD', quiet=True)
current_branch_name = ref_name.replace('refs/heads/', '')
return current_branch_name
def git_symbolic_ref(ref, quiet=False):
args = ['git', 'symbolic-ref', ref]
if quiet:
args.append('-q')
proc = subprocess.Popen(args, stdout=subprocess.PIPE)
stdout, stderr = proc.communicate()
return stdout.strip()
def git_checkout(branch_name):
subprocess.check_call(['git', 'checkout', branch_name])
def git_has_uncommited_changes():
return subprocess.call(['git', 'diff', '--quiet', '--exit-code']) == 1
# Command
def die(msg):
print("ERROR: %s" % msg, file=sys.stderr)
sys.exit(1)
def usage(msg=None):
if msg:
print("ERROR: %s" % msg, file=sys.stderr)
prog = "schema_diff.py"
args = ["<db-url>", "<orig-branch:orig-version>",
"<new-branch:new-version>"]
print("usage: %s %s" % (prog, ' '.join(args)), file=sys.stderr)
sys.exit(1)
def parse_options():
try:
db_url = sys.argv[1]
except IndexError:
usage("must specify DB connection url")
try:
orig_branch, orig_version = sys.argv[2].split(':')
except IndexError:
usage('original branch and version required (e.g. master:82)')
try:
new_branch, new_version = sys.argv[3].split(':')
except IndexError:
usage('new branch and version required (e.g. master:82)')
return db_url, orig_branch, orig_version, new_branch, new_version
def main():
timestamp = datetime.datetime.utcnow().strftime("%Y%m%d_%H%M%S")
ORIG_DB = 'orig_db_%s' % timestamp
NEW_DB = 'new_db_%s' % timestamp
ORIG_DUMP = ORIG_DB + ".dump"
NEW_DUMP = NEW_DB + ".dump"
options = parse_options()
db_url, orig_branch, orig_version, new_branch, new_version = options
# Since we're going to be switching branches, ensure user doesn't have any
# uncommitted changes
if git_has_uncommited_changes():
die("You have uncommitted changes. Please commit them before running "
"this command.")
db_driver = _get_db_driver_class(db_url)()
users_branch = git_current_branch_name()
git_checkout(orig_branch)
try:
# Dump Original Schema
dump_db(db_driver, ORIG_DB, db_url, orig_version, ORIG_DUMP)
# Dump New Schema
git_checkout(new_branch)
dump_db(db_driver, NEW_DB, db_url, new_version, NEW_DUMP)
diff_files(ORIG_DUMP, NEW_DUMP)
finally:
git_checkout(users_branch)
if os.path.exists(ORIG_DUMP):
os.unlink(ORIG_DUMP)
if os.path.exists(NEW_DUMP):
os.unlink(NEW_DUMP)
if __name__ == "__main__":
main()