astarte_appengine_api fails to start if astarte_events is not declared yet by astarte_data_updater_plant

[shinnokdisengir]

Description

The astarte_appengine_api crashes and ingress responds a Bad Gateway in some cases - it is not a systematic problem, but a corner case - caused by the astarte_events exchange present in the DUP (astarte_data_updater_plant) project.

Logs

2024-07-11 09:50:45 level=error ts=2024-07-11T07:50:45.930+00:00 msg="GenServer Astarte.AppEngine.API.Rooms.AMQPClient terminating
** (stop) exited in: :gen_server.call(#PID<0.1116.0>, {:call, {:\"queue.bind\", 0, \"astarte_rooms_events\", \"astarte_events\", \"astarte_rooms\", false, []}, :none, #PID<0.1104.0>}, 70000)
    ** (EXIT) shutdown: {:server_initiated_close, 404, \"NOT_FOUND - no exchange 'astarte_events' in vhost '/'\"}
    (stdlib 5.1) gen_server.erl:401: :gen_server.call/3
    (amqp 3.3.0) lib/amqp/queue.ex:101: AMQP.Queue.bind/4
    (astarte_appengine_api 1.2.0-dev) lib/astarte_appengine_api/rooms/amqp_client.ex:153: Astarte.AppEngine.API.Rooms.AMQPClient.setup_channel/1
    (astarte_appengine_api 1.2.0-dev) lib/astarte_appengine_api/rooms/amqp_client.ex:127: Astarte.AppEngine.API.Rooms.AMQPClient.connect/0
    (astarte_appengine_api 1.2.0-dev) lib/astarte_appengine_api/rooms/amqp_client.ex:94: Astarte.AppEngine.API.Rooms.AMQPClient.handle_info/2
    (stdlib 5.1) gen_server.erl:1077: :gen_server.try_handle_info/3
    (stdlib 5.1) gen_server.erl:1165: :gen_server.handle_msg/6
    (stdlib 5.1) proc_lib.erl:241: :proc_lib.init_p_do_apply/3
Last message: :try_to_connect
State: :not_connected" module=gen_server function=error_info/8
2024-07-11 09:50:45 level=notice ts=2024-07-11T07:50:45.939+00:00 msg="Application astarte_appengine_api exited: shutdown" module=application_controller function=info_exited/3

Steps to Reproduce

• Start the all astarte services.
• Ensure the astarte_events exchange has not been declared in the DUP project.
• Observe the Bad Gateway error in the logs.

Expected Behavior

The astarte_appengine_api should start without errors even if the astarte_events exchange is not pre-declared.

Actual Behavior

The astarte_appengine_api crashes, ingress cannot redirect incoming messages and responds with a Bad Gateway error.

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Possible Solution

A possible solution would be declaring the astarte_events exchange also in AppEngine, should it be idempotent.