Use metadata.create_all() to initialise DB schema

There is no need to run database migration each time, when we want to
get a new actual database schema. Running all migration scripts takes a
long time on production databases and can be not suitable for SQLite
because of Alembic limitation.

Added create_schema() method, which supposes to be used for initial
installation instead of upgrade('head').

Partial-Bug: #1347604

Change-Id: I039d955f051eda015bef2299122fd1f0fb5c46da

ironic/cmd/dbsync.py

@@ -47,6 +47,9 @@ class DBCommand(object):
     def version(self):
         print(migration.version())
 
+    def create_schema(self):
+        migration.create_schema()
+
 
 def add_command_parsers(subparsers):
     command_object = DBCommand()
@@ -71,6 +74,9 @@ def add_command_parsers(subparsers):
     parser = subparsers.add_parser('version')
     parser.set_defaults(func=command_object.version)
 
+    parser = subparsers.add_parser('create_schema')
+    parser.set_defaults(func=command_object.create_schema)
+
 
 command_opt = cfg.SubCommandOpt('command',
                                 title='Command',
@@ -85,7 +91,7 @@ def main():
     # pls change it to ironic-dbsync upgrade
     valid_commands = set([
         'upgrade', 'downgrade', 'revision',
-        'version', 'stamp'
+        'version', 'stamp', 'create_schema',
     ])
     if not set(sys.argv) & valid_commands:
         sys.argv.append('upgrade')

ironic/db/migration.py

@@ -45,3 +45,7 @@ def stamp(version):
 
 def revision(message, autogenerate):
     return IMPL.revision(message, autogenerate)
+
+
+def create_schema():
+    return IMPL.create_schema()

ironic/db/sqlalchemy/migration.py

@@ -19,8 +19,10 @@ import os
 import alembic
 from alembic import config as alembic_config
 import alembic.migration as alembic_migration
+from oslo.db import exception as db_exc
 
 from ironic.db.sqlalchemy import api as sqla_api
+from ironic.db.sqlalchemy import models
 
 
 def _alembic_config():
@@ -29,12 +31,13 @@ def _alembic_config():
     return config
 
 
-def version(config=None):
+def version(config=None, engine=None):
     """Current database version.
 
     :returns: Database version
     :rtype: string
     """
+    if engine is None:
         engine = sqla_api.get_engine()
     with engine.connect() as conn:
         context = alembic_migration.MigrationContext.configure(conn)
@@ -53,6 +56,25 @@ def upgrade(revision, config=None):
     alembic.command.upgrade(config, revision or 'head')
 
 
+def create_schema(config=None, engine=None):
+    """Create database schema from models description.
+
+    Can be used for initial installation instead of upgrade('head').
+    """
+    if engine is None:
+        engine = sqla_api.get_engine()
+
+    # NOTE(viktors): If we will use metadata.create_all() for non empty db
+    #                schema, it will only add the new tables, but leave
+    #                existing as is. So we should avoid of this situation.
+    if version(engine=engine) is not None:
+        raise db_exc.DbMigrationError("DB schema is already under version"
+                                      " control. Use upgrade() instead")
+
+    models.Base.metadata.create_all(engine)
+    stamp('head', config=config)
+
+
 def downgrade(revision, config=None):
     """Used for downgrading database.
 

ironic/tests/db/sqlalchemy/test_migrations.py

@@ -42,7 +42,7 @@ import contextlib
 
 from alembic import script
 import mock
-from oslo.db import exception
+from oslo.db import exception as db_exc
 from oslo.db.sqlalchemy import test_base
 from oslo.db.sqlalchemy import test_migrations
 from oslo.db.sqlalchemy import utils as db_utils
@@ -315,9 +315,33 @@ class MigrationCheckersMixin(object):
         #                Ironic will use oslo.db 0.4.0 or higher.
         #                See bug #1214341 for details.
         self.assertRaises(
-            (sqlalchemy.exc.IntegrityError, exception.DBDuplicateEntry),
+            (sqlalchemy.exc.IntegrityError, db_exc.DBDuplicateEntry),
             nodes.insert().execute, data)
 
+    def test_upgrade_and_version(self):
+        with patch_with_engine(self.engine):
+            self.migration_api.upgrade('head')
+            self.assertIsNotNone(self.migration_api.version())
+
+    def test_create_schema_and_version(self):
+        with patch_with_engine(self.engine):
+            self.migration_api.create_schema()
+            self.assertIsNotNone(self.migration_api.version())
+
+    def test_upgrade_and_create_schema(self):
+        with patch_with_engine(self.engine):
+            self.migration_api.upgrade('31baaf680d2b')
+            self.assertRaises(db_exc.DbMigrationError,
+                              self.migration_api.create_schema)
+
+    def test_upgrade_twice(self):
+        with patch_with_engine(self.engine):
+            self.migration_api.upgrade('31baaf680d2b')
+            v1 = self.migration_api.version()
+            self.migration_api.upgrade('head')
+            v2 = self.migration_api.version()
+            self.assertNotEqual(v1, v2)
+
 
 class TestMigrationsMySQL(MigrationCheckersMixin,
                           WalkVersionsMixin,