What is service discovery, and how does it work in microservices?

Service discovery is a mechanism in distributed systems for dynamically finding the locations and metadata of other services. It is crucial in microservice architectures, enhancing system resilience, scalability, and high availability. It is applied in cloud-native environments such as Kubernetes, supporting dynamic scaling and fault recovery through automatic service interconnection.

Core components include service registries (e.g., etcd or Consul) and service clients. When a service starts, it registers its IP and port with the registry; clients query via APIs to obtain a list of available instances. This enables load balancing, health checks, and dynamic routing, significantly simplifying microservice network management, reducing manual configuration errors, and improving cross-environment deployment efficiency.

In microservices, the workflow is as follows: 1. A service automatically registers with the registry upon startup. 2. A client (e.g., an API gateway) queries the registry to get a list of instances. 3. A load balancer selects an instance for invocation. Typical applications include A/B testing and rolling updates. Business value is reflected in simplified operations, enhanced service discovery speed, support for auto-scaling, and reduced costs.