GRPC_DNS_SRV_LOOKUP_FAILED grpc network_error ai_generated true

UNAVAILABLE: dns resolver: failed to query DNS SRV record for _grpc._tcp.example.com: lookup _grpc._tcp.example.com: no such host

ID: grpc/name-resolver-failure-dns

Also available as: JSON · Markdown · 中文
90%Fix Rate
87%Confidence
1Evidence
2024-01-10First Seen

Version Compatibility

VersionStatusIntroducedDeprecatedNotes
gRPC-go v1.62.0 active — — —
gRPC-java v1.61.0 active — — —
C-core v1.62.0 active — — —

Root Cause

gRPC's DNS resolver tried to resolve a SRV record for the service but the DNS server returned NXDOMAIN because the SRV record is missing or misconfigured.

generic

中文

gRPC 的 DNS 解析器尝试解析服务的 SRV 记录，但 DNS 服务器返回 NXDOMAIN，因为 SRV 记录缺失或配置错误。

Official Documentation

https://grpc.io/docs/guides/dns-naming/

Workarounds

  1. 95% success Add the missing SRV record in DNS: _grpc._tcp.example.com. 3600 IN SRV 0 0 50051 server1.example.com. Also ensure A/AAAA records exist for server1.example.com. 
    Add the missing SRV record in DNS: _grpc._tcp.example.com. 3600 IN SRV 0 0 50051 server1.example.com. Also ensure A/AAAA records exist for server1.example.com.
  2. 90% success Use the 'passthrough' resolver to bypass SRV lookup: set target URI to 'passthrough:///server1.example.com:50051' which resolves using standard A/AAAA records only. 
    Use the 'passthrough' resolver to bypass SRV lookup: set target URI to 'passthrough:///server1.example.com:50051' which resolves using standard A/AAAA records only.
  3. 85% success Configure a custom resolver in code: in Go, implement resolver.Builder and register it with resolver.Register(myBuilder) to provide a static list of addresses. 
    Configure a custom resolver in code: in Go, implement resolver.Builder and register it with resolver.Register(myBuilder) to provide a static list of addresses.

中文步骤

  1. Add the missing SRV record in DNS: _grpc._tcp.example.com. 3600 IN SRV 0 0 50051 server1.example.com. Also ensure A/AAAA records exist for server1.example.com.
  2. Use the 'passthrough' resolver to bypass SRV lookup: set target URI to 'passthrough:///server1.example.com:50051' which resolves using standard A/AAAA records only.
  3. Configure a custom resolver in code: in Go, implement resolver.Builder and register it with resolver.Register(myBuilder) to provide a static list of addresses.

Dead Ends

Common approaches that don't work:

  1. 90% fail

    Adding a fallback to IP address in the target URI (e.g., dns:///192.168.1.1:50051) bypasses service discovery entirely, breaking load balancing and failover.

  2. 85% fail

    Disabling DNS resolution with grpc.lb_policy=round_robin does not fix the missing SRV record; the resolver still fails before load balancing starts.