Periodic DNS resolution

[onlynone]

This should allow both the oss and plus versions to do periodic DNS resolution by using a variable in the proxy_pass and eliminating the jump through an upstream.

[dekobon]

Thank you for taking the time to put together this PR.

Unfortunately, there are some invisible side-effects of this change:

• Loss of keep-alive connections
• Loss of statistics for upstream

Also, DNS resolution for OSS is currently in review, so first-class support for it should be coming in the near term.

Out of the above issue, the loss of keep-alive connections is a significant drawback for the S3 use case. Please let me know what your thoughts are.

[dekobon]

By the way, I cherry-picked in the commit for fixing the $s3uri case.

[onlynone]

Also, DNS resolution for OSS is currently in review, so first-class support for it should be coming in the near term.

That would be great. I hope that feature gets merged soon.

Out of the above issue, the loss of keep-alive connections is a significant drawback for the S3 use case. Please let me know what your thoughts are.

Can you explain how significant the keep-alive connections are with S3? Is there no way to get keep-alive connections without going through an upstream?

[dekobon]

DNS resolution has been open sourced: https://blog.nginx.org/blog/dynamic-dns-resolution-open-sourced-in-nginx

Closing in favor of changes that use the OSS approach