Check the application logs and they'll confirm the problem:
kubectl logs -l app=todo-list,component=save-handler
Shows that the message handler can't connect to the queue:
Connecting to message queue url: nats://todo-list-queue:4222 Unhandled exception. NATS.Client.NATSNoServersException: Unable to connect to a server.
kubectl logs -l app=todo-list,component=web --tail 100
Shows that the website can't connect to the database:
---> MySql.Data.MySqlClient.MySqlException (0x80004005): Unable to connect to any of the specified MySQL hosts
Check the configuration objects for the app to find the expected domain names for the message queue and database.
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