Make database downgrade works

Fixes bug #854905

Use sqlalchemy reflection whenever possible:
    http://sqlalchemy-migrate.readthedocs.org/en/latest/versioning.html

Work around sqlalchemy-migrate sqlite 'bool column not deletable' issue:
    http://code.google.com/p/sqlalchemy-migrate/issues/detail?id=143
    Add following sql scripts for sqlite:
        002_sqlite_downgrade.sql
        015_sqlite_downgrade.sql
        033_sqlite_downgrade.sql
        050_sqlite_downgrade.sql
        068_sqlite_downgrade.sql

Work around sqlalchemy-migrate sqlite 'table with foreign key column not
deletable' issue:
    http://code.google.com/p/sqlalchemy-migrate/issues/detail?id=94
    Add following sql scripts for sqlite:
        003_sqlite_downgrade.sql
        006_sqlite_downgrade.sql
        007_sqlite_downgrade.sql
        012_sqlite_upgrade.sql
        013_sqlite_downgrade.sql
        020_sqlite_downgrade.sql
        030_sqlite_downgrade.sql
        038_sqlite_downgrade.sql
        042_sqlite_downgrade.sql
        053_sqlite_downgrade.sql
        067_sqlite_downgrade.sql

Work around sqlalchemy-migrate 'migrate drops engine reference' issue:
    http://code.google.com/p/sqlalchemy-migrate/issues/detail?id=72

Add following sql scripts for long primary key to work with utf-8
mysql table:
    072_mysql_upgrade.sql

Add following sql scripts for postgresql:
    002_postgresql_downgrade.sql

Add snake walk test cases for database migration based on glance migration
test.

Change-Id: Ib454ecb4662bbf47736c1b12d9a4f969f180ceb6

2 files changed, 233 insertions, 0 deletions

diff --git a/nova/tests/test_migrations.conf b/nova/tests/test_migrations.conf
new file mode 100644
index 000000000..774f14994
--- /dev/null
+++ b/nova/tests/test_migrations.conf
@@ -0,0 +1,9 @@
+[DEFAULT]
+# Set up any number of migration data stores you want, one
+# The "name" used in the test is the config variable key.
+#sqlite=sqlite:///test_migrations.db
+sqlite=sqlite://
+#mysql=mysql://root:@localhost/test_migrations
+#postgresql=postgresql://user:pass@localhost/test_migrations
+[walk_style]
+snake_walk=yes
diff --git a/nova/tests/test_migrations.py b/nova/tests/test_migrations.py
new file mode 100644
index 000000000..b0caea220
--- /dev/null
+++ b/nova/tests/test_migrations.py
@@ -0,0 +1,224 @@
+# vim: tabstop=4 shiftwidth=4 softtabstop=4
+
+# Copyright 2010-2011 OpenStack, LLC
+# All Rights Reserved.
+#
+#    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.
+
+"""
+Tests for database migrations. This test case reads the configuration
+file test_migrations.conf for database connection settings
+to use in the tests. For each connection found in the config file,
+the test case runs a series of test cases to ensure that migrations work
+properly both upgrading and downgrading, and that no data loss occurs
+if possible.
+"""
+
+import ConfigParser
+import commands
+import os
+import unittest
+import urlparse
+
+import migrate.versioning.api as migration_api
+from migrate.versioning.repository import Repository
+from sqlalchemy import create_engine
+
+from nova import log as logging
+from nova import test
+
+LOG = logging.getLogger('nova.tests.test_migrations')
+
+
+class TestMigrations(unittest.TestCase):
+    """Test sqlalchemy-migrate migrations"""
+
+    TEST_DATABASES = {}
+    # Test machines can set the NOVA_TEST_MIGRATIONS_CONF variable
+    # to override the location of the config file for migration testing
+    CONFIG_FILE_PATH = os.environ.get('NOVA_TEST_MIGRATIONS_CONF',
+                                      os.path.join('test_migrations.conf'))
+    REPOSITORY_PATH = os.path.abspath(os.path.join('..', 'db', 'sqlalchemy',
+        'migrate_repo'))
+    REPOSITORY = Repository(REPOSITORY_PATH)
+
+    def __init__(self, *args, **kwargs):
+        super(TestMigrations, self).__init__(*args, **kwargs)
+
+    def setUp(self):
+        super(TestMigrations, self).setUp()
+
+        # Load test databases from the config file. Only do this
+        # once. No need to re-run this on each test...
+        LOG.debug('config_path is %s' % TestMigrations.CONFIG_FILE_PATH)
+        if not TestMigrations.TEST_DATABASES:
+            if os.path.exists(TestMigrations.CONFIG_FILE_PATH):
+                cp = ConfigParser.RawConfigParser()
+                try:
+                    cp.read(TestMigrations.CONFIG_FILE_PATH)
+                    defaults = cp.defaults()
+                    for key, value in defaults.items():
+                        TestMigrations.TEST_DATABASES[key] = value
+                    self.snake_walk = cp.getboolean('walk_style', 'snake_walk')
+                except ConfigParser.ParsingError, e:
+                    self.fail("Failed to read test_migrations.conf config "
+                              "file. Got error: %s" % e)
+            else:
+                self.fail("Failed to find test_migrations.conf config "
+                          "file.")
+
+        self.engines = {}
+        for key, value in TestMigrations.TEST_DATABASES.items():
+            self.engines[key] = create_engine(value)
+
+        # We start each test case with a completely blank slate.
+        self._reset_databases()
+
+    def tearDown(self):
+        super(TestMigrations, self).tearDown()
+
+        # We destroy the test data store between each test case,
+        # and recreate it, which ensures that we have no side-effects
+        # from the tests
+        self._reset_databases()
+
+    def _reset_databases(self):
+        def execute_cmd(cmd=None):
+            status, output = commands.getstatusoutput(cmd)
+            LOG.debug(output)
+            self.assertEqual(0, status)
+        for key, engine in self.engines.items():
+            conn_string = TestMigrations.TEST_DATABASES[key]
+            conn_pieces = urlparse.urlparse(conn_string)
+            if conn_string.startswith('sqlite'):
+                # We can just delete the SQLite database, which is
+                # the easiest and cleanest solution
+                db_path = conn_pieces.path.strip('/')
+                if os.path.exists(db_path):
+                    os.unlink(db_path)
+                # No need to recreate the SQLite DB. SQLite will
+                # create it for us if it's not there...
+            elif conn_string.startswith('mysql'):
+                # We can execute the MySQL client to destroy and re-create
+                # the MYSQL database, which is easier and less error-prone
+                # than using SQLAlchemy to do this via MetaData...trust me.
+                database = conn_pieces.path.strip('/')
+                loc_pieces = conn_pieces.netloc.split('@')
+                host = loc_pieces[1]
+                auth_pieces = loc_pieces[0].split(':')
+                user = auth_pieces[0]
+                password = ""
+                if len(auth_pieces) > 1:
+                    if auth_pieces[1].strip():
+                        password = "-p%s" % auth_pieces[1]
+                sql = ("drop database if exists %(database)s; "
+                       "create database %(database)s;") % locals()
+                cmd = ("mysql -u%(user)s %(password)s -h%(host)s "
+                       "-e\"%(sql)s\"") % locals()
+                execute_cmd(cmd)
+            elif conn_string.startswith('postgresql'):
+                database = conn_pieces.path.strip('/')
+                loc_pieces = conn_pieces.netloc.split('@')
+                host = loc_pieces[1]
+                auth_pieces = loc_pieces[0].split(':')
+                user = auth_pieces[0]
+                password = ""
+                if len(auth_pieces) > 1:
+                    if auth_pieces[1].strip():
+                        password = auth_pieces[1]
+                cmd = ("touch ~/.pgpass;"
+                       "chmod 0600 ~/.pgpass;"
+                       "sed -i -e"
+                       "'1{s/^.*$/\*:\*:\*:%(user)s:%(password)s/};"
+                       "1!d' ~/.pgpass") % locals()
+                execute_cmd(cmd)
+                sql = ("UPDATE pg_catalog.pg_database SET datallowconn=false "
+                       "WHERE datname='%(database)s';") % locals()
+                cmd = ("psql -U%(user)s -h%(host)s -c\"%(sql)s\"") % locals()
+                execute_cmd(cmd)
+                sql = ("SELECT pg_catalog.pg_terminate_backend(procpid) "
+                       "FROM pg_catalog.pg_stat_activity "
+                       "WHERE datname='%(database)s';") % locals()
+                cmd = ("psql -U%(user)s -h%(host)s -c\"%(sql)s\"") % locals()
+                execute_cmd(cmd)
+                sql = ("drop database if exists %(database)s;") % locals()
+                cmd = ("psql -U%(user)s -h%(host)s -c\"%(sql)s\"") % locals()
+                execute_cmd(cmd)
+                sql = ("create database %(database)s;") % locals()
+                cmd = ("psql -U%(user)s -h%(host)s -c\"%(sql)s\"") % locals()
+                execute_cmd(cmd)
+
+    def test_walk_versions(self):
+        """
+        Walks all version scripts for each tested database, ensuring
+        that there are no errors in the version scripts for each engine
+        """
+        for key, engine in self.engines.items():
+            self._walk_versions(engine, self.snake_walk)
+
+    def _walk_versions(self, engine=None, snake_walk=False):
+        # Determine latest version script from the repo, then
+        # upgrade from 1 through to the latest, with no data
+        # in the databases. This just checks that the schema itself
+        # upgrades successfully.
+
+        # Place the database under version control
+        migration_api.version_control(engine, TestMigrations.REPOSITORY)
+        self.assertEqual(0,
+                migration_api.db_version(engine,
+                                         TestMigrations.REPOSITORY))
+
+        LOG.debug('latest version is %s' % TestMigrations.REPOSITORY.latest)
+
+        for version in xrange(1, TestMigrations.REPOSITORY.latest + 1):
+            # upgrade -> downgrade -> upgrade
+            migration_api.upgrade(engine, TestMigrations.REPOSITORY, version)
+            self.assertEqual(version,
+                    migration_api.db_version(engine,
+                                             TestMigrations.REPOSITORY))
+            if snake_walk:
+                migration_api.downgrade(engine,
+                                        TestMigrations.REPOSITORY,
+                                        version - 1)
+                self.assertEqual(version - 1,
+                        migration_api.db_version(engine,
+                                                 TestMigrations.REPOSITORY))
+                migration_api.upgrade(engine,
+                                      TestMigrations.REPOSITORY,
+                                      version)
+                self.assertEqual(version,
+                        migration_api.db_version(engine,
+                                                 TestMigrations.REPOSITORY))
+
+        # Now walk it back down to 0 from the latest, testing
+        # the downgrade paths.
+        for version in reversed(
+            xrange(0, TestMigrations.REPOSITORY.latest)):
+            # downgrade -> upgrade -> downgrade
+            migration_api.downgrade(engine, TestMigrations.REPOSITORY, version)
+            self.assertEqual(version,
+                    migration_api.db_version(engine,
+                                             TestMigrations.REPOSITORY))
+            if snake_walk:
+                migration_api.upgrade(engine,
+                                      TestMigrations.REPOSITORY,
+                                      version + 1)
+                self.assertEqual(version + 1,
+                        migration_api.db_version(engine,
+                                                 TestMigrations.REPOSITORY))
+                migration_api.downgrade(engine,
+                                        TestMigrations.REPOSITORY,
+                                        version)
+                self.assertEqual(version,
+                        migration_api.db_version(engine,
+                                                 TestMigrations.REPOSITORY))