Extend status_description column in Clusters tables

Convert column type to
 * Text for psql - unlimited size
 * LongText for mysql - max size 2^32

Also fixed template for autogenerated migrations: added a blank line to
avoid pep8 violation.

Closes-Bug: #1338933
Change-Id: Ie4c4f57aeb7ff03aa7f6077629f6463a136f8f4b

sahara/db/migration/alembic_migrations/script.py.mako

@@ -29,6 +29,7 @@ from alembic import op
 import sqlalchemy as sa
 ${imports if imports else ""}
 
+
 def upgrade():
     ${upgrades if upgrades else "pass"}
 

sahara/db/migration/alembic_migrations/versions/007_increase_status_description_size.py

@@ -0,0 +1,43 @@
+# Copyright 2014 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.
+
+"""convert clusters.status_description to LongText
+
+Revision ID: 007
+Revises: 006
+Create Date: 2014-06-20 22:36:00.783444
+
+"""
+
+# revision identifiers, used by Alembic.
+revision = '007'
+down_revision = '006'
+
+from alembic import op
+import sqlalchemy as sa
+
+from sahara.db.sqlalchemy import types as st
+
+
+def upgrade():
+    op.alter_column('clusters', 'status_description',
+                    type_=st.LongText(), existing_nullable=True,
+                    existing_server_default=None)
+
+
+def downgrade():
+    op.alter_column('clusters', 'status_description',
+                    type_=sa.String(length=200), existing_nullable=True,
+                    existing_server_default=None)

sahara/db/sqlalchemy/models.py

@@ -62,7 +62,7 @@ class Cluster(mb.SaharaBase):
     management_public_key = sa.Column(sa.Text, nullable=False)
     user_keypair_id = sa.Column(sa.String(80))
     status = sa.Column(sa.String(80))
-    status_description = sa.Column(sa.String(200))
+    status_description = sa.Column(st.LongText())
     info = sa.Column(st.JsonDictType())
     extra = sa.Column(st.JsonDictType())
     node_groups = relationship('NodeGroup', cascade="all,delete",

sahara/db/sqlalchemy/types.py

@@ -116,3 +116,9 @@ def LargeBinary():
     if base.is_mysql_avail():
         return mysql.LONGBLOB
     return sa.LargeBinary
+
+
+def LongText():
+    if base.is_mysql_avail():
+        return mysql.LONGTEXT
+    return sa.Text

sahara/tests/unit/db/migration/test_migrations.py

@@ -355,3 +355,17 @@ class TestMigrations(base.BaseWalkMigrationTestCase, base.CommonTestsMixIn):
     def _check_006(self, engine, data):
         # currently, 006 is just a placeholder
         self._check_001(engine, data)
+
+    def _check_007(self, engine, data):
+        self._check_001(engine, data)
+
+        # check that status_description can keep 128kb.
+        # MySQL varchar can not keep more then 64kb
+        desc = 'a' * 128 * 1024  # 128kb
+        t = db_utils.get_table(engine, 'clusters')
+        engine.execute(t.insert(), id='123', name='name', plugin_name='plname',
+                       hadoop_version='hversion', management_private_key='1',
+                       management_public_key='2', status_description=desc)
+        new_desc = engine.execute(t.select()).fetchone().status_description
+        self.assertEqual(desc, new_desc)
+        engine.execute(t.delete())