Question

Heroku makes deploying applications easy. It is a perfect platform for small to medium size web applications that are willing to sacrifice a little bit of flexibility in infrastructure to gain a fairly pain-free environment for deploying and maintaining web applications.

I am choosing to deploy our web application to Heroku for the sake of this tutorial because in my experience it has been the fastest way to get a web application up and running in no time. Remember that the focus of this tutorial is how to build web applications in Go and not getting caught up in all of the distraction of provisioning, configuring, deploying, and maintaining the machines that our Go code will be run on.

Getting setup

If you don't already have a Heroku account, sign up at id.heroku.com/signup . It's quick, easy and free.

Application management and configuration is done through the Heroku toolbelt, which is a free command line tool maintained by Heroku. We will be using it to create our application on Heroku. You can get it from toolbelt.heroku.com .

Changing the Code

To make sure the application from our last chapter will work on Heroku, we will need to make a few changes. Heroku gives us a PORT environment variable and expects our web application to bind to it. Let's start by importing the "os" package so we can grab that PORT environment variable:

import (
  "net/http"
  "os"

  "github.com/russross/blackfriday"
)

Next, we need to grab the PORT environment variable, check if it is set, and if it is we should bind to that instead of our hardcoded port (8080).

port := os.Getenv("PORT")
if port == "" {
  port = "8080"
}

Lastly, we want to bind to that port in our http.ListenAndServe call:

http.ListenAndServe(":"+port, nil)

The final code should look like this:

package main

import (
  "net/http"
  "os"

  "github.com/russross/blackfriday"
)

func main() {
  port := os.Getenv("PORT")
  if port == "" {
    port = "8080"
  }

  http.HandleFunc("/markdown", GenerateMarkdown)
  http.Handle("/", http.FileServer(http.Dir("public")))
  http.ListenAndServe(":"+port, nil)
}

func GenerateMarkdown(rw http.ResponseWriter, r *http.Request) {
  markdown := blackfriday.MarkdownCommon([]byte(r.FormValue("body")))
  rw.Write(markdown)
}

Configuration

We need a couple small configuration files to tell Heroku how it should run our application. The first one is the Procfile , which allows us to define which processes should be run for our application. By default, Go will name the executable after the containing directory of your main package. For instance, if my web application lived in GOPATH/github.com/codegangsta/bwag/deployment , my Procfile will look like this:

web: deployment

Specifically to run Go applications, we need to also specify a .godir file to tell Heroku which dir is in fact our package directory.

deployment

Deployment

Once all these things in place, Heroku makes it easy to deploy.

Initialize the project as a Git repository:

git init
git add -A
git commit -m "Initial Commit"

Create your Heroku application (specifying the Go buildpack):

heroku create -b https://github.com/kr/heroku-buildpack-go.git

Push it to Heroku and watch your application be deployed!

git push heroku master

View your application in your browser:

heroku open