Fix atomdetails failure column size

failure and revert_failure fields in atomdetails is defined as a JSON type,
but its data type is 'text' in mysql, which is limited to 64kbytes.
JSON data type should have the same size as a LONGTEXT.

Closes-Bug: #1959243
Change-Id: I65b6a6d896d3e8aad871dc19b0f8d0eddf48bdd6

taskflow/persistence/backends/sqlalchemy/alembic/versions/40fc8c914bd2_fix_atomdetails_failure_size.py

@@ -0,0 +1,36 @@
+#    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.
+
+"""fix atomdetails failure size
+
+Revision ID: 40fc8c914bd2
+Revises: 6df9422fcb43
+Create Date: 2022-01-27 18:10:06.176006
+
+"""
+
+# revision identifiers, used by Alembic.
+revision = '40fc8c914bd2'
+down_revision = '6df9422fcb43'
+
+from alembic import op
+from sqlalchemy.dialects import mysql
+
+
+def upgrade():
+    bind = op.get_bind()
+    engine = bind.engine
+    if engine.name == 'mysql':
+        op.alter_column('atomdetails', 'failure', type_=mysql.LONGTEXT,
+                        existing_nullable=True)
+        op.alter_column('atomdetails', 'revert_failure', type_=mysql.LONGTEXT,
+                        existing_nullable=True)