Document securing Eureka replication requests with custom filters

Contribution Overview

The Engineering Context

This contribution was made to the spring-cloud/spring-cloud-netflixopen-source repository. The work involved understanding the existing codebase, identifying the underlying engineering problem, implementing a focused solution, and validating the change against the project's existing behaviour and testing standards.

Original Issue

Document how to secure replication requests between Eureka servers.

Authentication mechanisms applied to normal Eureka client requests are not automatically applied to internal replication requests between Eureka nodes.

Engineering Problem

Understanding the Problem

Eureka replication requests between server nodes do not pass through the standard Spring Security filter chain. Developers therefore needed clearer guidance on how to customize outgoing replication requests and add authentication headers when securing Eureka clusters.

Solution

Implementation Approach

Added documentation explaining the Eureka replication request flow and demonstrated the use of ReplicationClientAdditionalFilters to customize outgoing replication requests, including scenarios such as injecting authentication headers or OAuth2 tokens.

Technologies

Engineering Stack