Add support to read path prefix from cluster specs

[blackjid]

This closes #421

Note to reviewers: remember to look at the commits in this PR and consider if they can be squashed
Note to contributors: remember to re-generate client set if there are any API changes

Summary Of Changes

This pr add support for the operator to look at the cluster specs for the path_prefix attribute if it is set. This way the operator can communicate with the cluster api while it can be exposed on a different path.

Additional Context

The additional_config property on the cluster spec adds configuration to for the cluster.
I understand the cluster support ini and sysctl like configurations.

• read configuration from the clusterspec
• make unit-tests PASS

ref:
https://www.rabbitmq.com/kubernetes/operator/using-operator.html#additional-config
https://www.rabbitmq.com/configure.html#config-file

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[coro]

Hi @blackjid, is this PR still WIP? Would you like the team's feedback on it yet?

[blackjid]

Hi @coro, well, I think it should be working.
There are still a few things to work on. But I think it might be a good idea to just expose it for feedback :)

[blackjid]

I'd love to have some feedback on the way to support both ini and sysctl config from the cluster.

For the ini syntax

Using go-ini/ini package works very nice to read the ini syntax. I think this is ok.

For the sysctl like syntax

I have been trying this, I have to approaches.

1. I haven't found an open library to parse this files, but the specification is pretty simple so I've implemented simple parser that is working fine in the tested scenarios.

2. I just find out that I could us the go-ini/library to parse the sysctl config, as it supports empty sections.

   Instead of doing this to read the value from a ini config

   cfg.Section("management").Key("path_prefix).String()
   

   I could do this from a sysctl config

   cfg.Section("").Key("management.path_prefix").String()
   

   The specification from the ini config is very similar to the sysctl, minus the sections.

What do you thing would be better? 1 or 2?

[coro]

Ah, there may be confusion from our documentation. RabbitMQ doesn't support the true .ini config format, only the sysctl format from a library called cuttlefish. The only rules of the syntax are:

• Everything you need to know about a single setting is on one line
• Lines are structured Key = Value
• Any line starting with # is a comment, and will be ignored.

(From https://github.com/basho/cuttlefish/wiki/Cuttlefish-for-Application-Users)

So in summary, you don't need to worry about .ini, only sysctl. The go-ini library you've chosen is great, and is what we use in the cluster-operator to set and parse the additional config files originally. Of your options for sysctl parsing above, I prefer the last one because it matches how the keys are set originally:

cfg.Section("").Key("management.path_prefix").String()

[blackjid]

Thanks for the feedback... that was exactly what I needed :)
I updated the PR with the latest changes, let me know if there is something else to add or change.

[coro]

LGTM! Let me pass this to another member of our team for a second opinion.

[ChunyiLyu]

Thank you for contributing!

[blackjid]

Thank you for contributing!

No problem!, I'm really happy to do it :)

Is there any plan of release this?

[ChunyiLyu]

@blackjid New release just cut 😊 See: https://github.com/rabbitmq/messaging-topology-operator/releases/tag/v1.8.0

[blackjid]

Awesome! Thanks