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Building a Server

Now that we've built a very simple image from scratch, let's get a bit more real-world, but before we Dockerize anything, we'll first build and run a web server without a container.

This step is only about getting your Go server running locally.

If you want your commands to match ours in the following lessons, name your project "goserver".

Assignment

If you haven't already, install Go and check that running go version works in your terminal.
Add the code at the bottom of this page to a main.go file in your project root.
run go mod init github.com/USERNAME/REPO after replacing USERNAME and REPO with your own values (I'm assuming you have a repo for this project).
Build the server: go build. This will create a standalone binary file in your current directory (the server application).
Run the server: ./goserver (where goserver is the name of the built binary; by default it's the same as your project's directory).
Make sure you can hit your server's endpoint(s) either in a browser or with curl. It should be available on localhost:8010.

Run and submit the CLI tests and then kill the server with Ctrl+C.

The Server Code

package main

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

func main() {
	m := http.NewServeMux()

	m.HandleFunc("/", handlePage)

	const port = "8010"
	srv := http.Server{
		Handler:      m,
		Addr:         ":" + port,
		WriteTimeout: 30 * time.Second,
		ReadTimeout:  30 * time.Second,
	}

	// this blocks forever, until the server
	// has an unrecoverable error
	fmt.Println("server started on", port)
	err := srv.ListenAndServe()
	log.Fatal(err)
}

func handlePage(w http.ResponseWriter, r *http.Request) {
	w.Header().Set("Content-Type", "text/html")
	w.WriteHeader(200)
	const page = `<html>
<head></head>
<body>
	<p> Hello from Docker! I'm a Go server. </p>
</body>
</html>
`
	w.Write([]byte(page))
}