JsonToGrpc GatewayFilter Factory

The JSONToGRPC GatewayFilter Factory converts a JSON payload to a gRPC request.

The filter takes the following arguments:

  • protoDescriptor: Proto descriptor file.

This file can be generated using protoc and specifying the --descriptor_set_out flag:

protoc --proto_path=src/main/resources/proto/ \
--descriptor_set_out=src/main/resources/proto/hello.pb  \
src/main/resources/proto/hello.proto

  • protoFile: Proto definition file.

  • service: Short name of the service that handles the request.

  • method: Method name in the service that handles the request.

streaming is not supported.

application.yml.

@Bean
public RouteLocator routes(RouteLocatorBuilder builder) {
    return builder.routes()
            .route("json-grpc", r -> r.path("/json/hello").filters(f -> {
                String protoDescriptor = "file:src/main/proto/hello.pb";
                String protoFile = "file:src/main/proto/hello.proto";
                String service = "HelloService";
                String method = "hello";
                return f.jsonToGRPC(protoDescriptor, protoFile, service, method);
            }).uri(uri))
spring:
  cloud:
    gateway:
      routes:
        - id: json-grpc
          uri: https://localhost:6565/testhello
          predicates:
            - Path=/json/**
          filters:
            - name: JsonToGrpc
              args:
                protoDescriptor: file:proto/hello.pb
                protoFile: file:proto/hello.proto
                service: HelloService
                method: hello

When a request is made through the gateway to /json/hello, the request is transformed by using the definition provided in hello.proto, sent to HelloService/hello, and the response back is transformed to JSON.

By default, it creates a NettyChannel by using the default TrustManagerFactory. However, you can customize this TrustManager by creating a bean of type GrpcSslConfigurer:

@Configuration
public class GRPCLocalConfiguration {
    @Bean
    public GRPCSSLContext sslContext() {
		TrustManager trustManager = trustAllCerts();
        return new GRPCSSLContext(trustManager);
    }
}