Fix Load Balancer Error in Java

Java Apps Behind Load Balancers

Java web applications — particularly Spring Boot — need explicit proxy configuration when deployed behind a load balancer. Without it, redirect URLs are wrong and session management breaks.

Spring Boot Proxy Headers

Tell Spring Boot to trust forwarded headers:

# application.yml
server:
  forward-headers-strategy: framework
  tomcat:
    remoteip:
      remote-ip-header: X-Forwarded-For
      protocol-header: X-Forwarded-Proto

Or in newer Spring Boot versions, simply:

server:
  forward-headers-strategy: native

Session Stickiness

If you use HTTP sessions, either enable sticky sessions on the load balancer or externalize sessions:

<!-- pom.xml -->
<dependency>
  <groupId>org.springframework.session</groupId>
  <artifactId>spring-session-data-redis</artifactId>
</dependency>

spring:
  session:
    store-type: redis
  redis:
    host: redis-service

Health Check Actuator

Spring Boot Actuator provides health endpoints out of the box:

management:
  endpoints:
    web:
      exposure:
        include: health
  endpoint:
    health:
      show-details: never

Point the load balancer at /actuator/health.

Timeout Alignment

The load balancer timeout must be shorter than the server's:

server:
  connection-timeout: 120000  # 120 seconds

Set ALB idle timeout to 90 seconds so it closes the connection before Tomcat does, preventing 502 errors.

Bugsly's Java SDK auto-captures exceptions with request context including the original client IP from X-Forwarded-For, so errors are attributed to real users, not the load balancer.