fix(polaris): prevent nil pointer panic when route rules don't match#3313
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cvictory wants to merge 1 commit into
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fix(polaris): prevent nil pointer panic when route rules don't match#3313cvictory wants to merge 1 commit into
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…3303) When Polaris route rules don't match (e.g., uid-only rules without discovery fallback), Route() could return an empty invoker slice, causing nil pointer panic in downstream cluster invokers. Add empty-result guard after ProcessRouters: if no invokers match the routed instances, fall back to original invokers with a warning log instead of returning an empty slice. Closes #3303
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AlexStocks
reviewed
Apr 29, 2026
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[P0] len(ret)==0 时直接回退到 invokers 会绕过真正生效的 Polaris 路由规则。ret 为空并不只代表“实例 ID 映射不上”，也可能是路由规则故意把当前请求全部过滤掉；这时正确行为应该是返回空结果并让上层按“无可用 provider”处理，而不是把原始 invokers 全部放回来继续发流量。现在的实现会把本应被路由规则拦掉的请求重新打到 provider 上，属于治理语义错误。
AlexStocks
reviewed
Apr 29, 2026
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| if len(ret) == 0 { |
Contributor
There was a problem hiding this comment.
[P0] len(ret)==0 时直接回退到 invokers 会绕过真正生效的 Polaris 路由规则。ret 为空并不只代表“实例 ID 映射不上”，也可能是路由规则故意把当前请求全部过滤掉；这时正确行为应该是返回空结果并让上层按“无可用 provider”处理，而不是把原始 invokers 全部放回来继续发流量。现在的实现会把本应被路由规则拦掉的请求重新打到 provider 上，属于治理语义错误。
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Bug
RouteRuleNotMatchfollowed by nil pointer panic.Route()incluster/router/polaris/router.goreturns an empty invoker slice whenProcessRoutersreturns instances that don't map to any known invoker. The empty slice propagates to cluster invokers (failfast, failover, etc.) which accessinvokers[0], causing nil pointer panic.Fix
After building the result from
ProcessRoutersresponse, if the result is empty (no matching invokers), log a warning and return the original invokers as a safe fallback. This follows the same defensive pattern used in 5 other error paths in the same method.Changed files:
cluster/router/polaris/router.go— 4-line empty-result guardcluster/router/polaris/router_test.go— 7 new regression tests with mock infrastructureVerification
go vet: cleango build: cleanTestRouteRuleNotMatchFallbackToOriginalInvokers— non-matching instances → fallbackTestRouteEmptyProcessRoutersResultFallbackToOriginalInvokers— empty result → fallbackTestRouteHappyPathReturnsMatchedInvokers— matching instances → filtered (behavior preserved)Closes #3303