Set the modulemd's context as the context in the DB to correct the current values

module_build_service/migrations/versions/708ac8950f55_set_from_mmd_context.py

@@ -0,0 +1,63 @@
+"""Sets the modulemd's context as the source of truth
+
+Revision ID: 708ac8950f55
+Revises: c8e2fc555399
+Create Date: 2018-05-29 13:49:43.629831
+
+"""
+
+# revision identifiers, used by Alembic.
+revision = '708ac8950f55'
+down_revision = 'c8e2fc555399'
+
+from alembic import op
+import sqlalchemy as sa
+
+# Data migration imports
+from module_build_service import Modulemd
+import hashlib
+
+
+modulebuild = sa.Table(
+    'module_builds',
+    sa.MetaData(),
+    sa.Column('id', sa.Integer, primary_key=True),
+    sa.Column('build_context', sa.String()),
+    sa.Column('runtime_context', sa.String()),
+    sa.Column('modulemd', sa.String()),
+    sa.Column('context', sa.String()),
+)
+
+
+def upgrade():
+    connection = op.get_bind()
+
+    for build in connection.execute(modulebuild.select()):
+        if not build.modulemd:
+            continue
+        try:
+            mmd = Modulemd.Module().new_from_string(build.modulemd)
+            mmd.upgrade()
+        except Exception:
+            # If the modulemd isn't parseable then skip this build
+            continue
+
+        # If the context in the modulemd doesn't match the context in the DB,
+        # then set the context in the DB to the one in the modulemd
+        mmd_context = mmd.get_context()
+        if mmd_context and mmd_context != build.context:
+            connection.execute(
+                modulebuild.update().where(modulebuild.c.id == build.id).values(
+                    context=mmd_context))
+
+
+def downgrade():
+    connection = op.get_bind()
+
+    for build in connection.execute(modulebuild.select()):
+        if build.build_context and build.runtime_context:
+            combined_hashes = '{0}:{1}'.format(
+                build.build_context, build.runtime_context).encode('utf-8')
+            context = hashlib.sha1(combined_hashes).hexdigest()[:8]
+            connection.execute(
+                modulebuild.update().where(modulebuild.c.id == build.id).values(context=context))