Service for local troubleshooting

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Sample demonstrating an easily broken service that is difficult to troubleshoot without careful investigation, and an improved version of the code.

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Code sample


// Sample hello demonstrates a difficult to troubleshoot service.
package main

import (

func main() {
	log.Print("hello: service started")

	http.HandleFunc("/", helloHandler)

	port := os.Getenv("PORT")
	if port == "" {
		port = "8080"
		log.Printf("Defaulting to port %s", port)

	log.Printf("Listening on port %s", port)
	log.Fatal(http.ListenAndServe(fmt.Sprintf(":%s", port), nil))

func helloHandler(w http.ResponseWriter, r *http.Request) {
	log.Print("hello: received request")

	name := os.Getenv("NAME")
	if name == "" {
		log.Printf("Missing required server parameter")
		// The panic stack trace appears in Cloud Error Reporting.
		panic("Missing required server parameter")

	fmt.Fprintf(w, "Hello %s!\n", name)


import static spark.Spark.get;
import static spark.Spark.port;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class App {

  private static final Logger logger = LoggerFactory.getLogger(App.class);

  public static void main(String[] args) {
    int port = Integer.parseInt(System.getenv().getOrDefault("PORT", "8080"));

        (req, res) -> {
"Hello: received request.");
          String name = System.getenv("NAME");
          if (name == null) {
            // Standard error logs do not appear in Stackdriver Error Reporting.
            System.err.println("Environment validation failed.");
            String msg = "Missing required server parameter";
            logger.error(msg, new Exception(msg));
            return "Internal Server Error";
          return String.format("Hello %s!", name);


const express = require('express');
const app = express();

app.get('/', (req, res) => {
  console.log('hello: received request.');

  const {NAME} = process.env;
  if (!NAME) {
    // Plain error logs do not appear in Stackdriver Error Reporting.
    console.error('Environment validation failed.');
    console.error(new Error('Missing required server parameter'));
    return res.status(500).send('Internal Server Error');
  res.send(`Hello ${NAME}!`);
const port = parseInt(process.env.PORT) || 8080;
app.listen(port, () => {
  console.log(`hello: listening on port ${port}`);


import json
import os

from flask import Flask

app = Flask(__name__)

@app.route("/", methods=["GET"])
def index():
    print("hello: received request.")

    NAME = os.getenv("NAME")

    if not NAME:
        print("Environment validation failed.")
        raise Exception("Missing required service parameter.")

    return f"Hello {NAME}"

if __name__ == "__main__":
    PORT = int(os.getenv("PORT")) if os.getenv("PORT") else 8080

    # This is used when running locally. Gunicorn is used to run the
    # application on Cloud Run. See entrypoint in Dockerfile."", port=PORT, debug=True)

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