In-class Go Exercise 3

Exercise · Explain This Go API Handler (HTTP Response)

Go · Beginner+

Explain this Go HTTP handler out loud like you're in a backend developer interview. Focus on the request, response writer, status code, and returned message.

package main

import (
	"fmt"
	"net/http"
)

func healthCheck(w http.ResponseWriter, r *http.Request) {

	w.WriteHeader(http.StatusOK)

	fmt.Fprintln(w, "API is running")

}

func main() {

	http.HandleFunc("/health", healthCheck)

	http.ListenAndServe(":8080", nil)

}

🎯 Instructions oral task

Explain what this program does.
Describe the purpose of the healthCheck function.
Explain what http.ResponseWriter is used for.
Explain what the request parameter represents.
Describe what StatusOK means.
Explain what message gets returned to the client.
Explain what happens when someone visits /health.

📖 Vocabulary core

HTTP handler — function that processes web requests.
endpoint — URL path used to access an API feature.
response — data sent back to the client.
status code — numeric HTTP result like 200 or 404.
request — incoming communication from a client.
server — application that listens for network requests.
client — user or application making the request.

🧩 Collocations natural English

handle an HTTP request
return a response
send back a status code
listen on a port
expose an API endpoint
write data to the response

🗣️ Phrasal Verbs interview speech

send back — “The server sends back a response.”
listen on — “The application listens on port 8080.”
set up — “The developer sets up a health check endpoint.”
write out — “The handler writes out a message.”

💬 Useful Interview Phrases communication

“This program creates a simple HTTP server...”
“The endpoint is responsible for...”
“The handler accepts a request and response writer...”
“The server returns a 200 OK response...”
“This endpoint can be used for monitoring or health checks.”
“The response body contains a simple status message.”

🎤 Model Answer spoken

This Go program creates a very simple HTTP server with a health check endpoint. The endpoint is available at /health.

The healthCheck function is an HTTP handler. It accepts two parameters: a response writer and a request object. The request contains information from the client request, while the response writer is used to send data back to the client.

Inside the handler, the server sends the HTTP status code 200 OK using w.WriteHeader(http.StatusOK). This indicates that the request was successful.

After that, the program writes the message API is running to the response body using fmt.Fprintln().

In the main function, the program registers the handler for the /health endpoint and starts the web server on port 8080. So when a user visits the endpoint, the server responds with a success message and a 200 status code.