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Add lazy DNS balancing for hostname upstreams in BalancedPool. When an upstream hostname resolves to multiple DNS records, new connections now rotate across the resolved addresses instead of always using a single result. This keeps the public BalancedPool API synchronous while deferring DNS resolution until connection time. Preserve the logical upstream origin so request Host headers and TLS servername handling continue to use the original hostname rather than the resolved IP address. Also add a regression test covering hostname upstream balancing across multiple resolved DNS records and verifying Host header preservation.
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can you update the docs? |
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Add regression coverage for hostname DNS balancing in BalancedPool, including lookup errors, duplicate records, empty results, and the all-clients-busy path. Document that hostname upstreams are resolved lazily at connect time and that requests preserve the original Host header and TLS servername.
metcoder95
approved these changes
Apr 7, 2026
ronag
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Apr 7, 2026
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I think this would work better as an interceptor. IMHO balanced pool should be deprecated in favor of that.
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This relates to...
Rationale
BalancedPooltreated hostname upstreams as a single origin and did not spread new connections across all DNS records returned for that hostname. This change resolves hostname upstreams lazily at connect time and rotates connections across the resolved addresses without changing the synchronousBalancedPoolAPI.Changes
BalancedPoolHostheaders and TLSservernameFeatures
Bug Fixes
BalancedPoolnow balances hostname upstreams across resolved DNS records instead of reusing a single resolved addressHostand TLSservernamewhile connecting through the resolved IPsBreaking Changes and Deprecations
Status