Hello Go Webserver!

Let’s spin up a simple webserver using Golang to handle HTTP requests and serve HTML content rendered from template files.

Prerequisites:

Working go installation¹

Part 1: Basic webserver

Create a directory for the project (mine is named websrv-proj) and place the following in a file named main.go.

~/websrv-proj/main.go

package main

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

// baseHandler is run when the server receives a request to the 
// "<server-address>:<server-port>/" url route.
func baseHandler(w http.ResponseWriter, r *http.Request) {
  fmt.Fprint(w, "Hello World!")
}

// main() registers http handlers, and starts listening for inbound TCP 
// requests on port `:8888`.
func main() {
  http.HandleFunc("/", baseHandler)
  log.Fatal(http.ListenAndServe(":8888", nil))
}

We can run this script and make requests to the server via command line or web browser.

~/websrv-proj

$ go run main.go &
$ curl http://localhost:8888/
Hello World!

string-resp

Part 2: Render HTML from Template

Okay, so we have a server listening on a port and it’s ready to handle requests to the “/” route. Let’s make this a webpage and return some HTML instead of a string. Let’s create a simple template file² in the project directory.

~/websrv-proj/index.html.tmpl

<!doctype html>
<html>
  <head>
  </head>
  <body>
    <div>
      <p>{{ . }}</p>
    </div>
  </body>
</html>

Now we have a template file that’s expecting a single template variable as input. We can update the handler to execure the template with a string argument and return the rendered HTML.

func handler(w http.ResponseWriter, r *http.Request) {
  t, _ := template.ParseFiles("index.html.tmpl")
  t.Execute(w, "Hello World!"); err != nil {
}

html-resp

Part 3: Extend the HTML template

We can update our template to make it easier to add new functionality.

<!doctype html>
<html lang="en">
  <head>
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no">
    <meta name="description" content="site">
    <title>site</title>

    <link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/[email protected]/dist/css/bootstrap.min.css" integrity="sha384-xOolHFLEh07PJGoPkLv1IbcEPTNtaed2xpHsD9ESMhqIYd0nLMwNLD69Npy4HI+N" crossorigin="anonymous">
  </head>
  <body>
    <main class="container" style="padding: 25px;">
      <div>
      <figure class="text-center">
        <blockquote class="blockquote">
          <p>{{ . }}</p>
        </blockquote>
      </figure>
      </div>
    </main>
  </body>
</html>

style-resp

Wrapping up

At this point we should have an HTTP server listening for requests to the / route on port :8888.

What next?

refactor into a module
add more pages and content
change the bootstrap theme / general styling
use a web framework / middleware package with more features
deploy on a cloud provider (Digital Ocean, Heroku, etc)
add a form and do something with the input
…