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What to say about deployment?

Wed 15 May 2013
By Harry

My book has got to the stage of a minimum viable site. I want the next chapter to be about actually deploying the site, even though it's ridiculously early -- to encourage the habit of "deploy early, deploy often".

But how to introduce deployment in a beginner-friendly way? It's a very simple site, so we don't need to cover all the complexities of deployment, but what's the minimum? Here's what I've got so far..


Deploying a site to a live web server can be a tricky topic. Oft heard in office corridors, IRC and tech forums is the forlorn cry -- "but it works on my machine"

Some of the danger areas of deployment include:

  • static files (CSS, javascript, images etc): web servers usually need special configuration for serving these
  • the database: there can be permissions and path issues, and we need to be careful about preserving data between deploys
  • dependencies: we need to make sure that the packages are software relies on are installed on the server, and have the correct versions

But there are solutions to all of these. In order:

  • Using a staging site, on the same infrastructure as the production site, can help us test out our deployments and get things right before we go to the "real" site
  • We can also run our functional tests against the staging site. They could include some smoke tests that, eg, CSS is loaded correctly.
  • We can write a special functional test that checks the deploy process, for example making sure database data is preserved (later, we can talk about South
  • data migrations...)
  • Virtualenvs are a useful tool for managing packages and dependencies on a server that's not entirely under your own control
  • And finally, automation, automation, automation. By using an automated script to deploy new versions, and by using the same script to deploy to staging and production, we can reassure ourselves that staging is as much like live as possible.

So far, so good (at least, I think. feel free to pick holes!)

But the question is: now what? What platform to choose to deploy to? What should be in my automated deploy script?

Platform:

  • Obviousy I think PythonAnywhere is the natural choice and the easiest and the best and stuff. But I would say that. So I can't say that
  • Heroku / Dotcloud et al are an option, but they involve quite a lot of specific config. The precise tools used to deploy are all different, and might change by the time the book comes out
  • How about "a generic VPS"? Assuming the user has SSH access, I could use fabric to deploy... That would let people use AWS, Digital Ocean, Linode or whoever. But then I get into the mess of apache / nginx / uwsgi config... and the trend these days seems to be to try and let users avoid that sort of hassle... Also, I really want to make sure people actually do this, and deploy their site, and I'd rather they were able to do it somewhere free...
  • Can I make some instructions generic enough that they apply to all platforms? I'm not sure...

So, your suggestions much appreciated! How do you do your deploys? Fabric? FTP? Git hooks? Something else? What do you think would work as a simple solution for beginners?

[update 2013-06-09] I've had a first bash at it, and the solution involves the reader starting up their own server, provisioning nginx + gunicorn + upstart, and deploying using fabric, git and virtualenvs. comments welcomed! You can find the current draft here]

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