rabbitmq-env.conf config value cannot use variable

[maxsky]

Describe the bug

When I set config PLUGINS_DIR to "/opt/local/var/lib/rabbitmq/plugins:${PLUGINS_DIR}"

in environments will see:

{plugins_dir,
          "/opt/local/lib/rabbitmq/lib/rabbitmq_server-4.0.7/plugins:/opt/local/var/lib/rabbitmq/plugins"}

but this time run rabbitmq-plugins enable rabbitmq_management rabbitmq_delayed_message_exchange

return {:plugins_not_found, [:rabbitmq_management]}

delayed message plugin in /opt/local/var/lib/rabbitmq/plugins

Only set this value will be fine:

PLUGINS_DIR="/opt/local/var/lib/rabbitmq/plugins:/opt/local/lib/rabbitmq/lib/rabbitmq_server-4.0.7/plugins"

Reproduction steps

1. Set like this PLUGINS_DIR="/opt/another/path/plugins:${PLUGINS_DIR}" to rabbitmq-env.conf file
2. run rabbitmq-plugins enable rabbitmq_management

Expected behavior

no plugins_not_found return

Additional context

No response

[michaelklishin]

@maxsky rabbitmq-env.conf has always been to be very limited in scope, by design: it allows you to list a number of environment variables in a KEY=value format, that's it. The docs do not advertise anything beyond that.

We plan to keep it that way. You can set the environment variables any other way, be it directly, via the systemd unit file or in the container runtime/orchestrator.