Let UNGLEICH_SITE_ALIASES show a site on another host

DOCKER.md

@@ -85,6 +85,8 @@ See [K8S.md](K8S.md) for the Kubernetes deployment.
 
 - `.env.docker`: committed dev defaults. `.env`: your overrides (git-ignored).
 - Add a site: add it to `UNGLEICH_SITE_CONFIGS` (a `Site` row is created on start).
+- Show an existing site on another host (a demo domain): `UNGLEICH_SITE_ALIASES={"demo.example.org":"datacenterlight.ch"}`.
+  `migrate` creates the alias and the host is added to `ALLOWED_HOSTS`. Unknown hosts are redirected to datacenterlight.ch.
 - Web server tuning: `GUNICORN_WORKERS` (3), `GUNICORN_TIMEOUT` (120).
 - Sample data off: `SEED_DUMMY_DATA=False`. Remove it later:
   `docker compose exec web python manage.py seed_dummy_data --purge`.

dynamicweb/management/commands/migrate.py

@@ -5,7 +5,8 @@ It replaces Django's own "migrate", so "python manage.py migrate" is all that ha
 - skips the migration-history consistency check when it fails, as it does on old databases
   that record some migrations as applied before the (newer) migrations they now depend on
 - gives pages that have no tree node one (see give_orphan_pages_a_node) before cms 0020
-- makes sure every site in UNGLEICH_SITE_CONFIGS exists
+- makes sure every site in UNGLEICH_SITE_CONFIGS exists, and every host in
+  UNGLEICH_SITE_ALIASES ({"alias host": "site domain"}) shows that site
 """
 import json
 import os
@@ -17,6 +18,7 @@ from django.db.migrations.executor import MigrationExecutor
 from django.db.migrations.exceptions import InconsistentMigrationHistory
 from django.db.migrations.loader import MigrationLoader
 from django.db.migrations.recorder import MigrationRecorder
+from multisite.models import Alias
 
 REVERSION_SQUASH = '0001_squashed_0004_auto_20160611_1202'
 REVERSION_FIXES = (
@@ -52,6 +54,8 @@ class Command(migrate.Command):
         if not dry_run and not options["app_label"]:
             for domain in json.loads(os.environ.get('UNGLEICH_SITE_CONFIGS') or '{}'):
                 Site.objects.get_or_create(domain=domain, defaults={'name': domain})
+            for alias, domain in json.loads(os.environ.get('UNGLEICH_SITE_ALIASES') or '{}').items():
+                Alias.objects.get_or_create(domain=alias, defaults={'site': Site.objects.get(domain=domain)})
 
     @staticmethod
     def cms_tree_done():

dynamicweb/settings/prod.py

@@ -26,3 +26,6 @@ ALLOWED_HOSTS = [
     ".hack4glarus.ch",
     ".xn--nglarus-n2a.ch"
 ]
+
+# hosts that UNGLEICH_SITE_ALIASES maps onto a site are allowed as well
+ALLOWED_HOSTS += list(json.loads(env('UNGLEICH_SITE_ALIASES', '{}')))