How to find RabbitMQ version inside a mapped volume before RabbitMQ server starts?

[joe-agent]

I have a custom script written in bash language. That script will run before CMD ["rabbitmq-server"] is called inside a custom RabbitMQ image container.

Where can I find the RabbitMQ version file within a RabbitMQ container?

[lukebakken]

Here's how I figured this out:

 docker run --name rabbitmq-727 --pull always  --rm -it -p 15672:15672 -p 5672:5672 rabbitmq:3-management

Then...

docker exec --interactive --tty rabbitmq-727 /bin/bash

Then, in the container, I ran ps -ef, and noted that RabbitMQ is installed to /opt/rabbitmq

root@5fc460a67742:/# ps -ef
UID          PID    PPID  C STIME TTY          TIME CMD
rabbitmq       1       0  0 15:50 pts/0    00:00:00 /bin/sh /opt/rabbitmq/sbin/rabbitmq-server

OK, fine, I know this container is running RabbitMQ 3.13.7, so maybe there is something with that version in the name:

root@cc2e562f3321:/opt/rabbitmq# find . -name '*3.13*'
...
...
./plugins/rabbit-3.13.7
...
...

OK, that means there will always be a directory with the form plugins/rabbit-VERSION. You could use that.

Maybe there is a file with 3.13.7 in it. It's easy to check:

root@cc2e562f3321:/opt/rabbitmq# find . -type f -exec grep -F 3.13.7 {} +

There are quite a few files returned that have 3.13.7 in them, but this one is the most promising:

./plugins/rabbit-3.13.7/ebin/rabbit.app:        {vsn, "3.13.7"},

Aha, you can find the current RabbitMQ version by searching for vsn in the /opt/rabbitmq/plugins/rabbit-*/ebin/rabbit.app file. Done.

[michaelklishin]

Note that occasionally this mechanism won't be perfectly reliable rabbitmq/rabbitmq-server#12339.

I'd use the package archive filename. Those by definition won't be incorrect or they will be retracted/never published.

[michaelklishin]

Where can I find the RabbitMQ version file within a RabbitMQ container?

rabbitmqctl version

will give you the CLI tools version but it is always the same as the RabbitMQ server version (unless you have multiple installations, that is).

[joe-agent]

Can rabbitmqctl command work before CMD ["rabbitmq-server"] runs?

[michaelklishin]

Yes. Some commands will require an explicit --offline but version is not one of them.

RabbitMQ must be installed before you run them but IAM sure that's obvious to you :)