Overview of the Project

This project consists of two main components:

• GRPC-Server: A gRPC server that listens on port 9090 and supports TLS for secure communication.

• Spring Cloud Gateway: A Spring Cloud Gateway application that acts as a reverse proxy, forwarding HTTP requests to the gRPC server over HTTP/2 with TLS.

Both applications are configured to use TLS for secure communication.

GRPC-Server

Purpose:

The grpc-server is a gRPC-based server that listens on port 9090 and supports secure communication via TLS. It is configured to use a certificate (certificate.pem) and private key (private.key) for TLS.

Configuration:

The configuration is defined in application.yaml:

grpc:
  enabled: true
  server:
    port: 9090
    security:
      enabled: true
      certificate-chain: classpath:certificate.pem
      private-key: classpath:private.key
    http2:
      enabled: true

How to Run:

Navigate to the grpc-server directory:

1. server Start the server using Maven:

cd grpc-server
mvn spring-boot:run

2. gateway Purpose:

The gateway is a Spring Cloud Gateway application that acts as a reverse proxy. It forwards HTTP requests to the grpc-server over HTTP/2 with TLS. It includes a route (/hello/**) that maps to the gRPC server's sayHello method in the HelloWorldService. Configuration:

The configuration is defined in application.yaml:

server:
  port: 8080
  http2:
    enabled: true
  ssl:
    enabled: true
    key-store: classpath:keystore.p12
    key-store-password: password
    key-store-type: PKCS12

spring:
  cloud:
    gateway:
      httpclient:
        ssl:
          trustedX509Certificates:
            - classpath:certificate.pem
      routes:
        - id: json-hello
          uri: https://localhost:9090
          predicates:
            - Path=/hello/**
          filters:
            - name: JsonToGrpc
              args:
                protoDescriptor: classpath:hello.pb
                protoFile: classpath:hello.proto
                service: HelloWorldService
                method: sayHello

How to Run:

Navigate to the gateway directory: gateway Start the gateway using Maven:

cd gateway
mvn spring-boot:run

Testing the Spring Cloud Gateway with TLS

Prerequisites

1. Ensure the following files are present in the classpath:

certificate.pem: The public certificate for TLS. private.key: The private key for the gRPC server. keystore.p12: The keystore for the gateway. hello.pb and hello.proto: The gRPC protocol buffer descriptor and definition files. Install Java and Maven on your system.

Verify that ports 8080 (gateway) and 9090 (gRPC server) are available.

Steps to Test

Start the gRPC Server:

Navigate to the grpc-server directory and run:

cd grpc-server
mvn spring-boot:run

The server will start on https://localhost:9090. Start the Gateway:

Navigate to the gateway directory and run:

cd gateway
mvn spring-boot:run

The gateway will start on https://localhost:8080. Send a Request to the Gateway:

Use a tool like curl or Postman to send a request to the gateway. Example curl command:

curl -k -X POST https://localhost:8080/hello/sayHello \
  -H "Content-Type: application/json" \
  -d '{"name": "John"}'

The gateway will forward the request to the gRPC server, and you should receive a response.

Verify the Response:

Check the response from the gateway to ensure it matches the expected output from the gRPC server.

How TLS Works in This Setup

grpc-server:

The server uses its private key (private.key) and public certificate (certificate.pem) to establish a secure connection with clients. The certificate is used to prove the server's identity to clients. gateway:

The gateway uses its keystore (keystore.p12) to secure communication with clients. It also uses the trusted certificate (certificate.pem) to verify the identity of the grpc-server when forwarding requests. Client Communication:

Clients (e.g., curl or Postman) communicate with the gateway over HTTPS (https://localhost:8080). The gateway forwards the request to the grpc-server over HTTPS (https://localhost:9090).

Summary

The grpc-server is a secure gRPC server that listens on port 9090 and supports HTTP/2 with TLS. The gateway is a Spring Cloud Gateway application that forwards HTTP requests to the gRPC server over HTTP/2 with TLS. To test the setup, start both applications and send a request to the gateway, which will forward it to the gRPC server.

Run grpc-server

  cd grpc-server
  mvn spring-boot:run

Run gateway

  cd grpc-server
  mvn spring-boot:run

Test

To test the setup, start both applications and send a request to the gateway, which will forward it to the gRPC server.