Make manage.py migrate handle restored old databases and create the sites

DOCKER.md

@@ -76,6 +76,8 @@ One image, `dynamicweb:latest`, serves every role; the `ROLE` variable picks it
 The entrypoint only picks the role, creates a secret key if `DJANGO_SECRET_KEY` is empty and waits for
 Postgres. The settings read `POSTGRES_*` directly, so you can also override `command:` (for example
 `python manage.py migrate` in an init container); then set `DJANGO_SECRET_KEY` yourself.
+`migrate` is the project's own: it also copes with a restored old database and creates the sites
+from `UNGLEICH_SITE_CONFIGS`.
 See [K8S.md](K8S.md) for the Kubernetes deployment.
 
 ## Configuration

dynamicweb/management/commands/migrate.py

@@ -0,0 +1,55 @@
+"""migrate, made safe for databases restored from the old (Django 1.9) installation.
+
+It replaces Django's own "migrate", so "python manage.py migrate" is all that has to run:
+- brings the old django-reversion 1.x tables to the schema of the squashed 3.x migration
+- skips the migration-history consistency check on old databases, which record some
+  migrations as applied before the (newer) migrations they now depend on
+- makes sure every site in UNGLEICH_SITE_CONFIGS exists
+"""
+import json
+import os
+
+from django.contrib.sites.models import Site
+from django.core.management.commands import migrate
+from django.db import connection
+from django.db.migrations.loader import MigrationLoader
+from django.db.migrations.recorder import MigrationRecorder
+
+REVERSION_SQUASH = '0001_squashed_0004_auto_20160611_1202'
+REVERSION_FIXES = (
+    'ALTER TABLE reversion_revision DROP COLUMN manager_slug',
+    'ALTER TABLE reversion_version DROP COLUMN object_id_int',
+    'ALTER TABLE reversion_version ALTER COLUMN object_id TYPE varchar(191)',
+    "ALTER TABLE reversion_version ADD COLUMN db varchar(191) NOT NULL DEFAULT 'default'",
+    'ALTER TABLE reversion_version ALTER COLUMN db DROP DEFAULT',
+    'ALTER TABLE reversion_version ADD CONSTRAINT reversion_version_db_unique '
+    'UNIQUE (db, content_type_id, object_id, revision_id)',
+)
+
+
+class Command(migrate.Command):
+    requires_system_checks = []   # as before: the start-up never ran them
+
+    def handle(self, *args, **options):
+        dry_run = options['plan'] or options['check_unapplied']
+        if not dry_run:
+            self.prepare_old_database()
+        super().handle(*args, **options)
+        if not dry_run:
+            for domain in json.loads(os.environ.get('UNGLEICH_SITE_CONFIGS') or '{}'):
+                Site.objects.get_or_create(domain=domain, defaults={'name': domain})
+
+    def prepare_old_database(self):
+        recorder = MigrationRecorder(connection)
+        recorder.ensure_schema()
+        applied = recorder.migration_qs
+        # django-reversion 3.x only ships one squashed migration that would
+        # re-create the tables, so fix the old ones and record it as applied.
+        if (applied.filter(app='reversion', name='0002_auto_20141216_1509').exists()
+                and not applied.filter(app='reversion', name=REVERSION_SQUASH).exists()):
+            with connection.cursor() as cursor:
+                for sql in REVERSION_FIXES:
+                    cursor.execute(sql)
+            recorder.record_applied('reversion', REVERSION_SQUASH)
+        if applied.filter(app='cmsplugin_filer_image').exists():
+            MigrationLoader.check_consistent_history = lambda *args, **kwargs: None

start-web.sh

@@ -8,46 +8,7 @@ cd /usr/src/app
 export DJANGO_SETTINGS_MODULE=dynamicweb.settings
 
 if [ "${RUN_MIGRATIONS:-True}" = "True" ]; then
-python - <<'PYEOF'
-import json, os
-import django
-django.setup()
-from django.core.management import call_command
-from django.db.migrations.loader import MigrationLoader
-
-from django.db import connection
-from django.db.migrations.recorder import MigrationRecorder
-
-recorder = MigrationRecorder(connection)
-recorder.ensure_schema()
-legacy = recorder.migration_qs.filter(app='cmsplugin_filer_image').exists()
-# django-reversion 1.x tables: 3.x only ships one squashed migration that would
-# re-create them, so bring the old tables to its schema and record it as applied.
-squash = '0001_squashed_0004_auto_20160611_1202'
-if (recorder.migration_qs.filter(app='reversion', name='0002_auto_20141216_1509').exists()
-        and not recorder.migration_qs.filter(app='reversion', name=squash).exists()):
-    with connection.cursor() as cursor:
-        for sql in (
-            'ALTER TABLE reversion_revision DROP COLUMN manager_slug',
-            'ALTER TABLE reversion_version DROP COLUMN object_id_int',
-            'ALTER TABLE reversion_version ALTER COLUMN object_id TYPE varchar(191)',
-            "ALTER TABLE reversion_version ADD COLUMN db varchar(191) NOT NULL DEFAULT 'default'",
-            'ALTER TABLE reversion_version ALTER COLUMN db DROP DEFAULT',
-            'ALTER TABLE reversion_version ADD CONSTRAINT reversion_version_db_unique '
-            'UNIQUE (db, content_type_id, object_id, revision_id)',
-        ):
-            cursor.execute(sql)
-    recorder.record_applied('reversion', squash)
-# Old databases can have a migration applied before the (newer) migrations it now
-# depends on, which Django refuses; for them migrate with that check switched off.
-if legacy:
-    MigrationLoader.check_consistent_history = lambda *args, **kwargs: None
-call_command('migrate', interactive=False, skip_checks=True)
-
-from django.contrib.sites.models import Site
-for domain in json.loads(os.environ.get('UNGLEICH_SITE_CONFIGS') or '{}'):
-    Site.objects.get_or_create(domain=domain, defaults={'name': domain})
-PYEOF
+    python manage.py migrate --noinput
 fi
 
 if [ "${MIGRATE_ONLY:-False}" = "True" ]; then