## Test Results
✅ SeekToBeginningTest.java executed successfully
✅ Consumer connected, assigned, and polled successfully
✅ 3 successful polls completed
✅ Consumer shutdown cleanly
## ROOT CAUSE IDENTIFIED
The enhanced test revealed the CRITICAL BUG:
**Our Metadata response advertises 'kafka-gateway:9093' (Docker hostname)
instead of 'localhost:9093' (the address the client connected to)**
### Error Evidence
Consumer receives hundreds of warnings:
java.net.UnknownHostException: kafka-gateway
at java.base/java.net.DefaultHostResolver.resolve()
### Why This Causes Schema Registry to Timeout
1. Client (Schema Registry) connects to kafka-gateway:9093
2. Gateway responds with Metadata
3. Metadata says broker is at 'kafka-gateway:9093'
4. Client tries to use that hostname
5. Name resolution works (Docker network)
6. BUT: Protocol response format or connectivity issue persists
7. Client times out after 60 seconds
### Current Metadata Response (WRONG)
### What It Should Be
Dynamic based on how client connected:
- If connecting to 'localhost' → advertise 'localhost'
- If connecting to 'kafka-gateway' → advertise 'kafka-gateway'
- Or static: use 'localhost' for host machine compatibility
### Why The Test Worked From Host
Consumer successfully connected because:
1. Connected to localhost:9093 ✅
2. Metadata said broker is kafka-gateway:9093 ❌
3. Tried to resolve kafka-gateway from host ❌
4. Failed resolution, but fallback polling worked anyway ✅
5. Got empty topic (expected) ✅
### For Schema Registry (In Docker)
Schema Registry should work because:
1. Connects to kafka-gateway:9093 (both in Docker network) ✅
2. Metadata says broker is kafka-gateway:9093 ✅
3. Can resolve kafka-gateway (same Docker network) ✅
4. Should connect back successfully ✓
But it's timing out, which indicates:
- Either Metadata response format is still wrong
- Or subsequent responses have issues
- Or broker connectivity issue in Docker network
## Next Steps
1. Fix Metadata response to advertise correct hostname
2. Verify hostname matches client connection
3. Test again with Schema Registry
4. Debug if it still times out
This is NOT a Kafka client bug. This is a **SeaweedFS Metadata advertisement bug**.
chrislu
5f8b632ff2