Add support to specify cluster_partition_handling through ENV vars

[boeboe]

Used in a Kubernetes context, it is very convenient to be able to specify the cluster partition handling as documented at https://www.rabbitmq.com/partitions.html

Using the RABBITMQ_CLUSTER_PARTITION_HANDLING environment value is a flexible solution.

[tianon]

See docker-library/docs#1011.

[vovandodev]

I've added this lines to my docker-entrypoint.sh
Also added export RABBITMQ_CLUSTER_PARTITION_HANDLING="pause_minority" into container. But it's not working. It's very important for me to test pause minority now. But due to automatic recreating of the config file, I can't do that. What should I adjust to be able to run it? :) Thanks.

[yosifkit]

@noteits, I would assume that these changes would work, but I have never used them. We try to keep what the entrypoint uses to a minimal set, which is why this PR is not merged.

One suggestion is using RABBITMQ_SERVER_ADDITIONAL_ERL_ARGS. Or if you are using rabbitmq:3.7, you can use the newer config format: https://www.rabbitmq.com/configure.html#config-file and the file will not be completely overwritten when you provide any of the env vars. So you can provide a base config built into your image with values that are not supported by the entrypoint and then customize it on deployment with the environment variables.

[vovandodev]

Thanks for your explanations, but unfortunately I am using 3.6.14.
I've added this changes to the docker-entrypoint.sh in container and restarted it.
sed -i "68i cluster_partition_handling" docker-entrypoint.sh
sed -i /'verify|fail_if_no_peer_cert|depth)'/d docker-entrypoint.sh
sed -i "217i verify|fail_if_no_peer_cert|depth|cluster_partition_handling)" docker-entrypoint.sh
Also
echo $RABBITMQ_CLUSTER_PARTITION_HANDLING
pause_minority

But it's not working. Is any other solution how to add pause_minority to config file? :(

[yosifkit]

with 3.7's simpler config format, we'd rather move to doing less config via the entrypoint

- #202 (comment)