@LoadBalanced RestTemplate should support direct IP address and localhost requests

[xzxiaoshan]

Describe the bug/feture When using RestTemplate with @LoadBalanced annotation, it cannot make requests to direct addresses like IP addresses (http://192.168.1.110:8080) or localhost (http://localhost:8080). The load balancer interceptor attempts to resolve these through service discovery, causing request failures.

Expected Behavior @LoadBalanced RestTemplate should intelligently distinguish between:

• Direct requests - IP addresses and localhost calls that should bypass service discovery
• Service discovery requests - Service names that should go through load balancing

Proposed Solution

Modify the load balancer detection logic to identify direct requests by these patterns:

• localhost calls with explicit ports: http://localhost:8080
• IP address calls with explicit ports: http://192.168.1.110:8080
• IPv6 addresses with ports: http://[::1]:8080

Enhancement to Service ID Resolution

For service discovery compatibility:

Change service ID extraction from just host to host:port format Schema (http/https) can be ignored in service ID resolution as it's not typically relevant for service discovery This maintains backward compatibility while providing more precise service identification

Sample Code

@Autowired
private RestTemplate loadBalancedRestTemplate;

// Direct requests - should bypass service discovery
loadBalancedRestTemplate.getForObject("http://192.168.1.110:8080/api/test", String.class);
loadBalancedRestTemplate.getForObject("http://localhost:8080/api/test", String.class);
loadBalancedRestTemplate.getForObject("http://10.0.0.1:9000/service", String.class);
loadBalancedRestTemplate.getForObject("http://[::1]:8080/ipv6", String.class);

// Service discovery requests - should use load balancing
loadBalancedRestTemplate.getForObject("http://user-service/api/users", String.class);

Benefits

Single RestTemplate instance can handle both direct and service calls Enhanced service ID resolution using host:port improves service discovery precision Maintains full backward compatibility Better developer experience without requiring multiple RestTemplate instances

Environment

Spring Cloud Commons version: [4.3.0]