6 files changed, 306 insertions, 0 deletions
diff --git a/oslo_db/sqlalchemy/migration_cli/README.rst b/oslo_db/sqlalchemy/migration_cli/README.rst
new file mode 100644
index 0000000..ebbbdcb
--- /dev/null
+++ b/oslo_db/sqlalchemy/migration_cli/README.rst
@@ -0,0 +1,9 @@
+This module could be used either for:
+1. Smooth transition from migrate tool to alembic
+2. As standalone alembic tool
+
+Core points:
+1. Upgrade/downgrade database with usage of alembic/migrate migrations
+or both
+2. Compatibility with oslo.config
+3. The way to autogenerate new revisions or stamps
diff --git a/oslo_db/sqlalchemy/migration_cli/__init__.py b/oslo_db/sqlalchemy/migration_cli/__init__.py
new file mode 100644
index 0000000..e69de29
--- /dev/null
+++ b/oslo_db/sqlalchemy/migration_cli/__init__.py
diff --git a/oslo_db/sqlalchemy/migration_cli/ext_alembic.py b/oslo_db/sqlalchemy/migration_cli/ext_alembic.py
new file mode 100644
index 0000000..243ae47
--- /dev/null
+++ b/oslo_db/sqlalchemy/migration_cli/ext_alembic.py
@@ -0,0 +1,78 @@
+#    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.
+
+import os
+
+import alembic
+from alembic import config as alembic_config
+import alembic.migration as alembic_migration
+
+from oslo_db.sqlalchemy.migration_cli import ext_base
+from oslo_db.sqlalchemy import session as db_session
+
+
+class AlembicExtension(ext_base.MigrationExtensionBase):
+
+    order = 2
+
+    @property
+    def enabled(self):
+        return os.path.exists(self.alembic_ini_path)
+
+    def __init__(self, migration_config):
+        """Extension to provide alembic features.
+
+        :param migration_config: Stores specific configuration for migrations
+        :type migration_config: dict
+        """
+        self.alembic_ini_path = migration_config.get('alembic_ini_path', '')
+        self.config = alembic_config.Config(self.alembic_ini_path)
+        # option should be used if script is not in default directory
+        repo_path = migration_config.get('alembic_repo_path')
+        if repo_path:
+            self.config.set_main_option('script_location', repo_path)
+        self.db_url = migration_config['db_url']
+
+    def upgrade(self, version):
+        return alembic.command.upgrade(self.config, version or 'head')
+
+    def downgrade(self, version):
+        if isinstance(version, int) or version is None or version.isdigit():
+            version = 'base'
+        return alembic.command.downgrade(self.config, version)
+
+    def version(self):
+        engine = db_session.create_engine(self.db_url)
+        with engine.connect() as conn:
+            context = alembic_migration.MigrationContext.configure(conn)
+            return context.get_current_revision()
+
+    def revision(self, message='', autogenerate=False):
+        """Creates template for migration.
+
+        :param message: Text that will be used for migration title
+        :type message: string
+        :param autogenerate: If True - generates diff based on current database
+                             state
+        :type autogenerate: bool
+        """
+        return alembic.command.revision(self.config, message=message,
+                                        autogenerate=autogenerate)
+
+    def stamp(self, revision):
+        """Stamps database with provided revision.
+
+        :param revision: Should match one from repository or head - to stamp
+                         database with most recent revision
+        :type revision: string
+        """
+        return alembic.command.stamp(self.config, revision=revision)
diff --git a/oslo_db/sqlalchemy/migration_cli/ext_base.py b/oslo_db/sqlalchemy/migration_cli/ext_base.py
new file mode 100644
index 0000000..205b7b2
--- /dev/null
+++ b/oslo_db/sqlalchemy/migration_cli/ext_base.py
@@ -0,0 +1,79 @@
+#    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.
+
+import abc
+
+import six
+
+
+@six.add_metaclass(abc.ABCMeta)
+class MigrationExtensionBase(object):
+
+    # used to sort migration in logical order
+    order = 0
+
+    @property
+    def enabled(self):
+        """Used for availability verification of a plugin.
+
+        :rtype: bool
+        """
+        return False
+
+    @abc.abstractmethod
+    def upgrade(self, version):
+        """Used for upgrading database.
+
+        :param version: Desired database version
+        :type version: string
+        """
+
+    @abc.abstractmethod
+    def downgrade(self, version):
+        """Used for downgrading database.
+
+        :param version: Desired database version
+        :type version: string
+        """
+
+    @abc.abstractmethod
+    def version(self):
+        """Current database version.
+
+        :returns: Databse version
+        :rtype: string
+        """
+
+    def revision(self, *args, **kwargs):
+        """Used to generate migration script.
+
+        In migration engines that support this feature, it should generate
+        new migration script.
+
+        Accept arbitrary set of arguments.
+        """
+        raise NotImplementedError()
+
+    def stamp(self, *args, **kwargs):
+        """Stamps database based on plugin features.
+
+        Accept arbitrary set of arguments.
+        """
+        raise NotImplementedError()
+
+    def __cmp__(self, other):
+        """Used for definition of plugin order.
+
+        :param other: MigrationExtensionBase instance
+        :rtype: bool
+        """
+        return self.order > other.order
diff --git a/oslo_db/sqlalchemy/migration_cli/ext_migrate.py b/oslo_db/sqlalchemy/migration_cli/ext_migrate.py
new file mode 100644
index 0000000..e31ee3d
--- /dev/null
+++ b/oslo_db/sqlalchemy/migration_cli/ext_migrate.py
@@ -0,0 +1,69 @@
+#    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.
+
+import logging
+import os
+
+from oslo_db._i18n import _LE
+from oslo_db.sqlalchemy import migration
+from oslo_db.sqlalchemy.migration_cli import ext_base
+from oslo_db.sqlalchemy import session as db_session
+
+
+LOG = logging.getLogger(__name__)
+
+
+class MigrateExtension(ext_base.MigrationExtensionBase):
+    """Extension to provide sqlalchemy-migrate features.
+
+    :param migration_config: Stores specific configuration for migrations
+    :type migration_config: dict
+    """
+
+    order = 1
+
+    def __init__(self, migration_config):
+        self.repository = migration_config.get('migration_repo_path', '')
+        self.init_version = migration_config.get('init_version', 0)
+        self.db_url = migration_config['db_url']
+        self.engine = db_session.create_engine(self.db_url)
+
+    @property
+    def enabled(self):
+        return os.path.exists(self.repository)
+
+    def upgrade(self, version):
+        version = None if version == 'head' else version
+        return migration.db_sync(
+            self.engine, self.repository, version,
+            init_version=self.init_version)
+
+    def downgrade(self, version):
+        try:
+            # version for migrate should be valid int - else skip
+            if version in ('base', None):
+                version = self.init_version
+            version = int(version)
+            return migration.db_sync(
+                self.engine, self.repository, version,
+                init_version=self.init_version)
+        except ValueError:
+            LOG.error(
+                _LE('Migration number for migrate plugin must be valid '
+                    'integer or empty, if you want to downgrade '
+                    'to initial state')
+            )
+            raise
+
+    def version(self):
+        return migration.db_version(
+            self.engine, self.repository, init_version=self.init_version)
diff --git a/oslo_db/sqlalchemy/migration_cli/manager.py b/oslo_db/sqlalchemy/migration_cli/manager.py
new file mode 100644
index 0000000..c8ab30e
--- /dev/null
+++ b/oslo_db/sqlalchemy/migration_cli/manager.py
@@ -0,0 +1,71 @@
+#    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.
+
+from stevedore import enabled
+
+
+MIGRATION_NAMESPACE = 'oslo.db.migration'
+
+
+def check_plugin_enabled(ext):
+    """Used for EnabledExtensionManager."""
+    return ext.obj.enabled
+
+
+class MigrationManager(object):
+
+    def __init__(self, migration_config):
+        self._manager = enabled.EnabledExtensionManager(
+            MIGRATION_NAMESPACE,
+            check_plugin_enabled,
+            invoke_kwds={'migration_config': migration_config},
+            invoke_on_load=True
+        )
+        if not self._plugins:
+            raise ValueError('There must be at least one plugin active.')
+
+    @property
+    def _plugins(self):
+        return sorted(ext.obj for ext in self._manager.extensions)
+
+    def upgrade(self, revision):
+        """Upgrade database with all available backends."""
+        results = []
+        for plugin in self._plugins:
+            results.append(plugin.upgrade(revision))
+        return results
+
+    def downgrade(self, revision):
+        """Downgrade database with available backends."""
+        # downgrading should be performed in reversed order
+        results = []
+        for plugin in reversed(self._plugins):
+            results.append(plugin.downgrade(revision))
+        return results
+
+    def version(self):
+        """Return last version of db."""
+        last = None
+        for plugin in self._plugins:
+            version = plugin.version()
+            if version:
+                last = version
+        return last
+
+    def revision(self, message, autogenerate):
+        """Generate template or autogenerated revision."""
+        # revision should be done only by last plugin
+        return self._plugins[-1].revision(message, autogenerate)
+
+    def stamp(self, revision):
+        """Create stamp for a given revision."""
+        return self._plugins[-1].stamp(revision)