feat: switch resolver to lua-resty-dns-client

[spacewander]

Fix #2532
Signed-off-by: spacewander spacewanderlzx@gmail.com

What this PR does / why we need it:

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• Did you explain what problem does this PR solve? Or what new features have been added?
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[jenskeiner]

Hey, thanks for taking care of this DNS issue.

I've been bitten by this as well in a K8s environment where I want to refer to services just by their name w/o the full domain part which is environment-specific. Let me know in case I can help with anything. Otherwise, looking forward to seeing this merged to master. +1

[spacewander]

We are planning to release 2.3, so this PR will be merged later. There will be more DNS relative new features in the coming 2.4 version.
CC @gy09535

[gy09535]

We are planning to release 2.3, so this PR will be merged later. There will be more DNS relative new features in the coming 2.4 version.
CC @gy09535

good, got it.

[ShaoZeMing]

I found a problem. At present, after using this dns client, upstream services can implement dns search, but in plugins, when resty.http is used to generate requests, dns search cannot be implemented. Is there a way to deal with this?

[membphis]

@ShaoZeMing Welcome to create a new journal to discuss your questions. This PR has been merged, which means it is complete.