Developing Web Applications with Haskell and Yesod

Chapter 11. Deploying Your Webapp

I can’t speak for others, but I personally prefer programming to system administration. But the fact is that, eventually, you need to serve your app somehow, and odds are that you’ll need to be the one to set it up.

There are some promising initiatives in the Haskell web community towards making deployment easier. In the future, we may even have a service that allows you to deploy your app with a single command.

But we’re not there yet. And even if we were, such a solution will never work for everyone. This chapter covers the different options you have for deployment, and gives some general recommendations on what you should choose in different situations.

Compiling

First things first: how do you build your production application? If you’re using the scaffolded site, it’s as simple as cabal build. I also recommend cleaning beforehand to make sure there is no cached information, so a simple combination to build your executable is:

cabal clean && cabal configure && cabal build

Warp

As we have mentioned before, Yesod is built on the Web Application Interface (WAI), allowing it to run on any WAI backend. At the time of writing, the following backends are available:

• Warp

• FastCGI

• SCGI

• CGI

• Webkit

• Development server

The last two are not intended for production deployments. Of the remaining four, all can be used for production deployment in theory. In practice, a CGI backend will likely be horribly inefficient, since a new process must be spawned for each connection. ...