4. Deployment

# Deployment Heroku makes deploying applications easy. It is a perfect platform for small tomedium size web applications that are willing to sacrifice a little bit offlexibility in infrastructure to gain a fairly pain-free environment fordeploying and maintaining web applications. I am choosing to deploy our web application to Heroku for the sake of thistutorial because in my experience it has been the fastest way to get a webapplication up and running in no time. Remember that the focus of this tutorialis how to build web applications in Go and not getting caught up in allof the distraction of provisioning, configuring, deploying, and maintaining themachines 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](https://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 tocreate our application on Heroku. You can get it from[toolbelt.heroku.com](https://toolbelt.heroku.com/). ## Changing the Code To make sure the application from our last chapter will work on Heroku, we willneed to make a few changes. Heroku gives us a `PORT` environment variableand 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, andif 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 ourapplication. The first one is the `Procfile`, which allows us to define whichprocesses should be run for our application. By default, Go will name theexecutable 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 totell 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 ~~~