Hello World service

#include <google/cloud/functions/framework.h>
#include <cstdlib>

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

auto hello_world_http() {
  return gcf::MakeFunction([](gcf::HttpRequest const& /*request*/) {
    std::string greeting = "Hello ";
    auto const* target = std::getenv("TARGET");
    greeting += target == nullptr ? "World" : target;
    greeting += "\n";

    return gcf::HttpResponse{}
        .set_header("Content-Type", "text/plain")
        .set_payload(greeting);
  });
}

int main(int argc, char* argv[]) {
  return gcf::Run(argc, argv, hello_world_http());
}

// Sample run-helloworld is a minimal Cloud Run service.
package main

import (
	"fmt"
	"log"
	"net/http"
	"os"
)

func main() {
	log.Print("starting server...")
	http.HandleFunc("/", handler)

	// Determine port for HTTP service.
	port := os.Getenv("PORT")
	if port == "" {
		port = "8080"
		log.Printf("defaulting to port %s", port)
	}

	// Start HTTP server.
	log.Printf("listening on port %s", port)
	if err := http.ListenAndServe(":"+port, nil); err != nil {
		log.Fatal(err)
	}
}

func handler(w http.ResponseWriter, r *http.Request) {
	name := os.Getenv("NAME")
	if name == "" {
		name = "World"
	}
	fmt.Fprintf(w, "Hello %s!\n", name)
}

package com.example.helloworld;

import org.springframework.beans.factory.annotation.Value;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

@SpringBootApplication
public class HelloworldApplication {

  @Value("${NAME:World}")
  String name;

  @RestController
  class HelloworldController {
    @GetMapping("/")
    String hello() {
      return "Hello " + name + "!";
    }
  }

  public static void main(String[] args) {
    SpringApplication.run(HelloworldApplication.class, args);
  }
}

import express from 'express';
const app = express();

app.get('/', (req, res) => {
  const name = process.env.NAME || 'World';
  res.send(`Hello ${name}!`);
});

const port = parseInt(process.env.PORT) || 8080;
app.listen(port, () => {
  console.log(`helloworld: listening on port ${port}`);
});

<?php

$name = getenv('NAME', true) ?: 'World';
echo sprintf('Hello %s!', $name);

import os

from flask import Flask

app = Flask(__name__)


@app.route("/")
def hello_world():
    """Example Hello World route."""
    name = os.environ.get("NAME", "World")
    return f"Hello {name}!"


if __name__ == "__main__":
    app.run(debug=True, host="0.0.0.0", port=int(os.environ.get("PORT", 8080)))

require "sinatra"

set :bind, "0.0.0.0"
port = ENV["PORT"] || "8080"
set :port, port

get "/" do
  name = ENV["NAME"] || "World"
  "Hello #{name}!"
end