Hello World, C++ Functions Framework

hello_world_http.cc

#include <google/cloud/functions/http_request.h>
#include <google/cloud/functions/http_response.h>
#include <nlohmann/json.hpp>

namespace gcf = ::google::cloud::functions;

gcf::HttpResponse hello_world_http(gcf::HttpRequest request) {
  auto greeting = [r = std::move(request)] {
    auto request_json = nlohmann::json::parse(r.payload(), /*cb=*/nullptr,
                                              /*allow_exceptions=*/false);
    if (request_json.count("name") && request_json["name"].is_string()) {
      return "Hello " + request_json.value("name", "World") + "!";
    }
    return std::string("Hello World!");
  };

  gcf::HttpResponse response;
  response.set_payload(greeting());
  response.set_header("content-type", "text/plain");
  return response;
}