Setting Up a gRPC Server in Spring Boot

Setting up a gRPC server in Spring Boot with grpc-spring-boot-starter is clean once you understand the dual-server model. Your application runs two servers simultaneously, and both need to be configured correctly.

The basic setup:

• Add net.devh:grpc-spring-boot-starter dependency, set grpc.server.port in application.yml — typically 9090 — and annotate your service implementation with @GrpcService
• The starter handles Netty server startup, service registration, and lifecycle management alongside the Spring context; your service class is a regular Spring bean with full support for constructor injection, @Transactional, and configuration properties
• On the client side, @GrpcClient injects a managed stub with a logical service name configured in YAML — addresses can switch from static:// for dev to dns:// for production service discovery without recompiling

The dual-server model — the critical detail:

• Your application runs HTTP on port 8080 and gRPC on port 9090; that means two health checks, potentially two TLS certificate sets for mTLS, and two port entries in your Kubernetes Service definition
• A common deployment mistake: the K8s manifest exposes only port 8080, so gRPC is unreachable in the cluster with no obvious error — the service starts fine but all gRPC clients get connection refused

Test configuration:

• Always set grpc.server.port: 0 in test properties to use a random port; parallel test suites binding the same port is a frequent CI failure source that's hard to debug

I recommend verifying both ports appear in your Kubernetes Service manifest before the first cluster deployment — and confirming the starter version matches your Spring Boot major version, since Boot 2.x and 3.x have different APIs that cause NoSuchMethodError on startup if mismatched.