Allow read-only mode

dcatd.yml

@@ -59,6 +59,7 @@ storage_postgres:
   pass: ${DB_PASS}
   port: ${DB_PORT}
   user: ${DB_USER}
+  mode: ${DB_MODE:-READWRITE}
 
 storage_swift:
   user: ${SWIFT_USER:-catalogus}

src/datacatalog/application.py

@@ -173,7 +173,8 @@ async def _on_startup(app):
         if r.exception is not None:
             raise r.exception
     await startup_actions.run_startup_actions(app)
-    await NotificationHandler(app).setup_notification_handling()
+    if app.config['storage_postgres'].get("mode", '') != "READONLY":
+        await NotificationHandler(app).setup_notification_handling()
 
 
 async def _on_cleanup(app):

src/datacatalog/plugins/postgres/__init__.py

@@ -144,7 +144,7 @@ async def initialize(app):
                 raise
         else:
             break
-    while connect_attempt_tries_left >= 0:
+    while connect_attempt_tries_left >= 0 and dbconf.get('mode', 'READWRITE') != "READONLY":
         try:
             await app['pool'].execute(_Q_CREATE)
             await app['pool'].execute(_Q_CREATE_STARTUP_ACTIONS)

src/datacatalog/plugins/postgres/config_schema.yml

@@ -27,6 +27,11 @@ properties:
         type: integer
       max_inactive_connection_lifetime:
         type: number
+      mode:
+        type: string
+        enum:
+          - READONLY
+          - READWRITE
     required:
       - host
       - port