Add and use Metadata in ConsulDiscoveryOptions

[cieciurm]

Description

Hello!

Thank you for delivering Steeltoe 😄 .

I was browsing through the good first issue label and wanted to contribue a change for #438.

I'd like to open discussions on the goals and some details regarding implementation before executing it without the alignment.

Here are my thoughts:

1. Currently ConsulDiscoveryOptions has a property called Tags (list of strings)
2. Tags are expected to be in format key=value
3. Internally some tags are added (such as group, instance zone)
4. Currently the fallback from Tags to Metadata happens in ConsulRegistration:

  Metadata = ConsulServerUtils.GetMetadata(agentServiceRegistration.Tags);

Here are my questions:

1. Would you like to keep the current behavior of usings tags as metadata? Should it be controlled by an option in ConsulDiscoveryOptions, f.e. for backwards compatibility?
2. I guess, you like to keep adding the internal metadata (such as group, instance zone)
3. What's the naming preference in ConsulDiscoveryOptions - should it be Metadata (well-known term) or Meta (Consul's AgentServiceRegistration propety is called Meta)

I hope, it's not too much - but I wanted to clarify before jumping to code immediately.

Once confirmed and agreed, I will finish the implementation (obviously including tests etc.).

Thanks in advance 😄 !

Fixes #438

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[hananiel]

Thank you for this PR. Since this PR is targeting main which will be release 4.x , we can deprecate the previous functionality with parsing tags as metadata. For functionality such as default groups, as well as property names, we should match as closely as possible the functionality described here: so Metadata for us. The prefix stays same as what is currently i.e. consul:discovery
If we back port to 3.x, we can consider a flag such as 'tagsAsMetadata'

[cieciurm]

Thanks for your response, @hananiel!

I've completed my first attempt at the implementation. Scope:

• Added the Metadata to ConsulDiscoveryOptions
• Switched the metadata generation (including the internal generated ones) from the original metadata instead of Tags
• Also exposed regular Tags to ConsulServiceInstance
• I've adjusted unit tests

Please let me know if something needs to be adjusted or changed.

Thanks a lot in advance!

[hananiel]

@cieciurm This looks good. Would you like to take a crack at updating the docs as well? The v4 docs are on this branch: https://github.com/SteeltoeOSS/Documentation/tree/v4

[cieciurm]

Thanks, @hananiel! You got it!

SteeltoeOSS/Documentation#302