Fixing RABBITMQ_CONFIG_ARG_FILE variable

[Gsantomaggio]

The rabbit_prelaunch module can read the os:getenv(RABBITMQ_CONFIG_ARG_FILE) correctly

Proposed Changes

With this PR the rabbit_prelaunch can read the variable RABBITMQ_CONFIG_ARG_FILE correctly.

Found the bug (RMQ 3.7.11) while I was trying to set:

[
 {kernel, [
    {inet_dist_listen_min, 50000},
    {inet_dist_listen_max, 50000}
    ]}
].

on the etc/rabbitmq/advanced.config file, and did not work.

The RABBITMQ_CONFIG_ARG_FILE was not read and the rabbitmq-server script always set the default values (PRELAUNCH_RESULT was always 0).

3.6.x had to do the same

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• New feature (non-breaking change which adds functionality)
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[lukebakken]

@Gsantomaggio thanks for noticing this. I think RABBITMQ_CONFIG_ARG_FILE needs to be removed as it isn't documented and only used by the prelaunch step ... and not very effectively at that. What makes this more complicated is the introduction of the rabbitmq.conf file whose contents can really only be verified after processing.

[lukebakken]

@Gsantomaggio advanced.config is only read if rabbitmq.conf is also present. You can use /etc/rabbitmq/rabbitmq.conf to set those values (schema):

inet_dist_listen_min = 50000
inet_dist_listen_max = 50000

Or, you can create the /etc/rabbitmq/rabbitmq.config file with your original, Erlang-term configuration.

[Gsantomaggio]

@lukebakken thanks
but I forgot to mention that:

$ cat etc/rabbitmq/rabbitmq.conf
vm_memory_high_watermark.relative = 0.3
inet_dist_listen_min = 50000
inet_dist_listen_max = 50000

does not work :)
see:

➜  rabbitmq_server-3.7.11 sbin/rabbitmqctl report | grep inet_dist_listen_min
      {inet_dist_listen_min,25672},

this because of the RABBITMQ_DIST_PORT is assigned during the rabbit_prelaunch

In 3.6.x it worked because of the value was read directly from the conf file

in 3.7.x is suppose to read RABBITMQ_CONFIG_ARG_FILE

[lukebakken]

@Gsantomaggio - I can reproduce this, but the fix will have to take rabbitmq.conf into account somehow. Let me see what we can come up with.

[Gsantomaggio]

@lukebakken I think the same, I was focusing on the advanced.config because I get this message:

Unable to update config for app kernel from a .conf file. The app is already running. 
Use advanced.config instead.

[lukebakken]

OK, since we generate config from rabbitmq.conf after the VM starts, we can't set these kernel values at that time. I'll take that into account too.

[lukebakken]

@Gsantomaggio I think your change will suffice, but I'm doing some testing and will remove the settings from the rabbit.schema file. I'm also testing net_ticktime since I don't trust that it will work.

[lukebakken]

You can change net_ticktime after the VM starts, but not the dist ports. We would have to run cuttlefish as part of the startup scripts to support that.

Also see rabbitmq/rabbitmq-website#687

Thanks @Gsantomaggio

[michaelklishin]

@Gsantomaggio please submit all future PRs against master.

[Gsantomaggio]

@michaelklishin I will.
I was looking for the stable branch, but I think you changed the repositories organization :)!

@lukebakken
I am going to remove this configuration from the rabbitmq.conf.example file