Add active health checks to TransportServer

[LorcanMcVeigh]

Proposed changes

This PR adds active health checks support to Transport Servers for NGINX Plus. It adds a health check field to yaml and fields for better configuring the health checks.

Checklist

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• I have read the CONTRIBUTING doc
• I have added tests that prove my fix is effective or that my feature works
• I have checked that all unit tests pass after adding my changes
• I have updated necessary documentation
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[pleshakov]

Hi @LorcanMcVeigh

Thanks for addressing feedback. I got a few more comments/suggestion related to the new code.

[soneillf5]

Can we remove the health check generation from this method?

At the moment, it appears to create a healthcheck for each upstream, but there is only one pointer. I think the value is overridden so it only returns the healthcheck for the last upstream, is this correct?

How about a new function, which takes the upstreams (transportServerEx.TransportServer.Spec.Upstreams ?) and returns the health checks for each one?

[LorcanMcVeigh]

At the moment, it appears to create a healthcheck for each upstream, but there is only one pointer. I think the value is overridden so it only returns the healthcheck for the last upstream, is this correct?

Yeah that's right, at the moment we don't support multiple health checks, so I'll refactor so that the only health check that's generated is the one that referenced the right upstream

[soneillf5]

I mentioned previously about the pointer override, assuming this is not intended behaviour, can we add a test to confirm that two upstreams generates two health checks ? I think there's multiple health checks in the tests below, but some of them are invalid ?

[soneillf5]

Looks great!