500 Server Error returned from SCG (Spring Cloud Gateway)

Products

• VMware Tanzu Application Platform

Issue/Introduction

500 Server Error is streaming in the SCG (Spring Cloud Gateway) pod. 

$ kubectl logs scg-pod -n app-ns 
...
{"level":"error","ts":"2024-12-29T22:13:52.811Z","logger":"org.springframework.web.server.adapter.HttpWebHandlerAdapter","thread":"reactor-http-epoll-1","context":"default","msg":"[fb84cd8d-687612] 500 Server Error for HTTP GET "/constraints/constraint-sets?dealerId=123456&product=ABCD"
...

Resolution

A possible reason is that the server is timing out idle connections. Because reactor-netty does not have a default idle time, the next time the gateway attempts to reuse an idle connection from the pool after that server timeout has elapsed, a failure is observed.

One solution is to turn off connection pooling by adding the SPRING_CLOUD_GATEWAY_HTTPCLIENT_POOL_TYPE environment variable to your SpringCloudGateway definition and setting the value to DISABLED. For example:

apiVersion: "tanzu.vmware.com/v1"
kind: SpringCloudGateway
metadata:
  name: test-gateway
spec:
  env:
    - name: SPRING_CLOUD_GATEWAY_HTTPCLIENT_POOL_TYPE
      value: DISABLED

The default value for SPRING_CLOUD_GATEWAY_HTTPCLIENT_POOL_TYPE is ELASTIC. Please see the difference between the two values:

• Elastic - connection pool enabled - reuse connections between requests
• Disabled - connection pool disabled - create a new connection for each request

Please raise a Tanzu support ticket if the above solution is not able to get issue solved.