rabbitmq_delayed_message_exchange is not compatible with 3.13.0 and khepri_db experimental feature

[pnchen]

Describe the bug

Error Info:

# rabbitmq-plugins enable rabbitmq_delayed_message_exchange
Enabling plugins on node rabbit@debian:
rabbitmq_delayed_message_exchange
The following plugins have been configured:
  rabbitmq_delayed_message_exchange
  rabbitmq_management
  rabbitmq_management_agent
  rabbitmq_mqtt
  rabbitmq_web_dispatch
  rabbitmq_web_mqtt
Applying plugin configuration to rabbit@debian...
Stack trace:

** (CaseClauseError) no case clause matching: {:badrpc, {:EXIT, {:aborted, {:node_not_running, :rabbit@debian}}}}
    (rabbitmqctl 3.13.0-dev) lib/rabbitmq/cli/plugins/plugins_helpers.ex:215: RabbitMQ.CLI.Plugins.Helpers.update_enabled_plugins/2
    (rabbitmqctl 3.13.0-dev) lib/rabbitmq/cli/plugins/plugins_helpers.ex:112: RabbitMQ.CLI.Plugins.Helpers.update_enabled_plugins/4
    (rabbitmqctl 3.13.0-dev) lib/rabbitmq/cli/plugins/commands/enable_command.ex:127: anonymous fn/6 in RabbitMQ.CLI.Plugins.Commands.EnableCommand.do_run/2
    (elixir 1.15.4) lib/stream.ex:1530: anonymous fn/2 in Stream.iterate/2
    (elixir 1.15.4) lib/stream.ex:1757: Stream.do_unfold/4
    (elixir 1.15.4) lib/stream.ex:1828: Enumerable.Stream.do_each/4
    (elixir 1.15.4) lib/stream.ex:1052: Stream.do_transform_inner_enum/7
    (elixir 1.15.4) lib/stream.ex:1828: Enumerable.Stream.do_each/4

{:case_clause, {:badrpc, {:EXIT, {:aborted, {:node_not_running, :rabbit@debian}}}}}

the node rabbit@debian is running, and plugins such as rabbitmq_mqtt has been enabled succesfully

Reproduction steps

• install the latest version of rabbitmq, follow https://www.rabbitmq.com/docs/install-debian#apt-quick-start-cloudsmith
• run rabbitmq-plugins enable rabbitmq_delayed_message_exchange

Expected behavior

enable the plugin without error

Additional context

No response

[mkuratczyk]

You are trying to enable a plugin while RabbitMQ is not running. Start RabbitMQ first.

[pnchen]

You are trying to enable a plugin while RabbitMQ is not running. Start RabbitMQ first.

Thanks! In my Environment, The RabbitMQ is already started And rabbitmq_mqtt can be enabled successfully.

if I stop RabbitMQ by running systemctl stop rabbitmq-server, then run rabbitmq-plugins enable rabbitmq_delayed_message_exchange it will show

Enabling plugins on node rabbit@debian:
rabbitmq_delayed_message_exchange
The following plugins have been configured:
  rabbitmq_delayed_message_exchange
  rabbitmq_management
  rabbitmq_management_agent
  rabbitmq_mqtt
  rabbitmq_web_dispatch
  rabbitmq_web_mqtt
Applying plugin configuration to rabbit@debian...
The following plugins have been enabled:
  rabbitmq_delayed_message_exchange

set 6 plugins.
Offline change; changes will take effect at broker restart.

But I can't start the RabbitMQ again , because rabbitmq_delayed_message_exchange will error at starting

[lukebakken]

Something similar was reported here - #269

@pnchen you MUST provide the EXACT steps you used to download and install this plugin. Please also provide the output of ls -la on the plugins directory in your environment.

[pnchen]

I found it because I enable the Feathure flag khepri_db. When I keep this disable every thing will OK.

Thanks to All

[michaelklishin]

@pnchen please never used issues for questions in repositories that have discussions enabled. This is just rude at this point, discussions have been around for a couple of years.

[michaelklishin]

This plugin is not compatible with Khepri because when Khepri is enabled, Mnesia is likely not even started, and this plugin uses Mnesia exclusively right now.

If someone wants it to be compatible, you are welcome to contribute a PR.

[michaelklishin]

As I was putting together an issue about Khepri support, I have realized a couple of things. This plugin cannot realistically use Khepri:

1. Khepri has a documented limitation where it stores the entire data set both on disk and in memory
2. This plugin stores the entire message content in the table, therefore, it explicitly goes against the recommendation for the current version of Khepri

Given that #229 will take a long time to finish regardless of the details, perhaps this plugin should be reworked to not store the payload in Mnesia. DETS is one readily available option with the known 4 GiB limit per file :(

[pnchen]

Sorry, I don't need to use Khepri. I misunderstand the Rabbitmq's warning At the top of management page ,and enabled all the feature flags.
Thanks for your reply