const interceptors = require('grpc-interceptors');

const server = interceptors.serverProxy(new grpc.Server());
server.addService(proto.MyPackage.MyService.service, { Method1, Method2 });

const myMiddlewareFunc = function (ctx, next) {

    // do stuff before call
    console.log('Making gRPC call...');

    await next()

    // do stuff after call
    console.log(ctx.status.code);
}

server.use(myMiddlewareFunc);