import ballerina/grpc;

listener grpc:Listener securedEP = new(9090,
    secureSocket = {
        key: {
            certFile: "../resource/path/to/public.crt",
            keyFile: "../resource/path/to/private.key"
        }
    }
);

// The service can be secured with OAuth2 authentication and can be authorized
// optionally. OAuth2 authentication can be enabled by setting the
// [`grpc:OAuth2IntrospectionConfig`](https://docs.central.ballerina.io/ballerina/grpc/latest/records/OAuth2IntrospectionConfig) configurations.
// Authorization is based on scopes. A scope maps to one or more groups.
// Authorization can be enabled by setting the `string|string[]` type
// configurations for `scopes` field.
@grpc:ServiceConfig {
    auth: [
        {
            oauth2IntrospectionConfig: {
                url: "https://localhost:9445/oauth2/introspect",
                tokenTypeHint: "access_token",
                scopeKey: "scp",
                clientConfig: {
                    customHeaders: {"Authorization": "Basic YWRtaW46YWRtaW4="},
                    secureSocket: {
                        cert: "../resource/path/to/public.crt"
                    }
                }
            },
            scopes: ["admin"]
        }
    ]
}
@grpc:ServiceDescriptor {
    descriptor: ROOT_DESCRIPTOR_GRPC_SERVICE,
    descMap: getDescriptorMapGrpcService()
}
service "HelloWorld" on securedEP {
    remote function hello() returns string {
        return "Hello, World!";
    }
}

Service - OAuth2

A gRPC service/resource can be secured using OAuth2 and by enforcing authorization optionally. Then, it validates the OAuth2 token sent in the Authorization metadata against the provided configurations. This calls the configured introspection endpoint to validate.
Ballerina uses the concept of scopes for authorization. A resource declared in a service can be bound to one/more scope(s). The scope can be included in the introspection response using a custom claim attribute. That custom claim attribute also can be configured as the scopeKey.
In the authorization phase, the scopes of the service/resource are compared against the scope included in the introspection response for at least one match between the two sets.

For more information on the underlying module, see the OAuth2 module.

syntax = "proto3";
import "google/protobuf/empty.proto";
import "google/protobuf/wrappers.proto";

This is the service definition for the scenario.

service HelloWorld {
	rpc hello(google.protobuf.Empty) returns (google.protobuf.StringValue);
}
# Create a new Protocol Buffers definition file named `grpc_service.proto` and add the service definition to it.
# Run the command below in the Ballerina tools distribution for stub generation.
bal grpc --input grpc_service.proto --output stubs
# Once you run the command, `grpc_service_pb.bal` file is generated inside stubs directory.
# For more information on how to use the Ballerina Protocol Buffers tool, see the [Proto To Ballerina](https://ballerina.io/learn/by-example/proto-to-ballerina.html) example.
import ballerina/grpc;
listener grpc:Listener securedEP = new(9090,
    secureSocket = {
        key: {
            certFile: "../resource/path/to/public.crt",
            keyFile: "../resource/path/to/private.key"
        }
    }
);
@grpc:ServiceConfig {
    auth: [
        {
            oauth2IntrospectionConfig: {
                url: "https://localhost:9445/oauth2/introspect",
                tokenTypeHint: "access_token",
                scopeKey: "scp",
                clientConfig: {
                    customHeaders: {"Authorization": "Basic YWRtaW46YWRtaW4="},
                    secureSocket: {
                        cert: "../resource/path/to/public.crt"
                    }
                }
            },
            scopes: ["admin"]
        }
    ]
}
@grpc:ServiceDescriptor {
    descriptor: ROOT_DESCRIPTOR_GRPC_SERVICE,
    descMap: getDescriptorMapGrpcService()
}
service "HelloWorld" on securedEP {
    remote function hello() returns string {
        return "Hello, World!";
    }
}

The service can be secured with OAuth2 authentication and can be authorized optionally. OAuth2 authentication can be enabled by setting the grpc:OAuth2IntrospectionConfig configurations. Authorization is based on scopes. A scope maps to one or more groups. Authorization can be enabled by setting the string|string[] type configurations for scopes field.

# Create a Ballerina package.
# Copy the generated `grpc_secured_pb.bal` stub file to the package.
# For example, if you create a package named `service`, copy the stub file to the `service` package.
# Create a new `grpc_service_oauth2.bal` Ballerina file inside the `service` package and add the service implementation.
# Execute the command below to build the 'service' package.
# You may need to change the certificate file path and private key file path.
`bal build service`
# Run the service using the command below.
bal run service/target/bin/service.jar