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Hello API Security + API Docs on Production?

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Friends! Welcome to part 2 of our API Platform series - the one where we're talking all about ice cream, um, security. We're talking about security, not uh, ice cream. Hmm. Um, it's going to be almost as awesome as ice cream though, because the topic of security - especially API security - is fascinating! We've got API tokens, session-based authentication, CSRF attacks, dragon attacks and the challenge of securing our API Platform application down to the smallest details, like letting different users see different records or even returning or accepting different fields based on the user. Yep, we're going to take this wonderful base that API platform has given us and shape it to act exactly like we need from a security perspective.

The great thing about API platform is that it's basically just... Symfony security. They didn't reinvent the wheel at all. If you haven't gone through our Symfony Security tutorial yet, now would be a good time: you'll feel much more dangerous after.

Anyways, let's dive into this! To put the lock down on your API Platform security skills, download the course code from this page and code along with me. After you unzip the file, you'll find a start/ directory that has the same code you see here. Open up the README.md file for all the details on getting the app set up. If you coded through part 1 of this tutorial, um, you rock, but also, I recommend downloading the new course code because I upgraded a few dependencies and added a frontend to the site.

Anyways, one of the last steps in the README will be to open a terminal, move into the project and run:

yarn encore dev --watch

to run Encore and build some JavaScript that'll power a small frontend. To make things more realistic, we'll do a little bit of work in JavaScript to see how it interacts with our API from an authentication standpoint. Next, open another terminal and start the Symfony local web server:

symfony serve

Once that starts, you should be able to fly back over to your browser and open up https://localhost:8000 to see... Cheese Whiz! The peer-to-peer cheese-selling app we build in part 1. Actually, this is our brand new Vue.js-powered frontend. OOOOooOOO. Go to /api. Ah yes, this is the API we built: we have a CheeseListing resource, a User resource, they're related to each other and we've customized a ton of stuff. In a bit, we'll start making this frontend talk to the API.

Hiding the Docs on Production?

But before we get there, head back to /api to see our beautiful, interactive, Swagger documentation. I know some of you are probably thinking: I know, this is great for development, but how can I disable this for production?

The answer is... you shouldn't!

Well first, let me show you how you can disable this on production and then I'll try to convince you to keep it.

Open up config/packages/api_platform.yaml. API Platform is highly configurable. So, reminder time: if you go to an open terminal, you can see all your current configuration - including any default values - by running:

php bin/console debug:config api_platform

You can also run:

php bin/console config:dump api_platform

to see an example tree of all the possible keys with some explanations. One of the options is called enable_docs. Copy this. The goal is to disable the docs only in production, but let's start by disabling them everywhere to see how it works.

Set enable_docs to false.

19 lines | config/packages/api_platform.yaml
// ... lines 2 - 17
enable_docs: false

Ok, go back and refresh /api. Um... there is absolutely no change! That's due to a small dev-only bug with a few of these options: when we change those options, they're not causing the routing cache to rebuild automatically. No big problem, clear that cache manually with:

php bin/console cache:clear

Fly back over, refresh and... yep! The documentation is gone. Oh... but instead of a 404, it's a 500 error!

It turns out that going to /api to see the docs was just a convenience. The documentation was really stored at /api/docs and this is now a 404. You could also go to /api/docs.json or /api/docs.jsonld before, but now it's all gone.

One of the unfortunate things about removing the documentation is that it wasn't just rendered as HTML. In part 1 of this series, we talked about JSON-LD and Hydra, and how API Platform generates machine-readable documentation to explain your API. If I go to /api/cheeses.jsonld, this advertises that we can go to /api/contexts/cheeses to get more "context", more machine-readable "meaning". Whelp, that doesn't work anymore. The point is: if you disable documentation, realize that you're also disabling the machine-friendly documentation.

And if you want to fix the 500 on /api, you also need to disable the "entrypoint". Right now, if we go to /api/index.jsonld, we get a, sort of, "homepage" for our API, which tells us what URLs we could go to next to discover more. When we go to /api, that's the HTML entrypoint and that's... totally broken. To disable that page set enable_entrypoint to false. Rebuild the cache:

20 lines | config/packages/api_platform.yaml
// ... lines 2 - 18
enable_entrypoint: false
php bin/console cache:clear

then go refresh. Now we get a 404 on this and /api.

So to fully disable your docs without a 500 error, you need both of these keys. To make this only happen in production, copy them, delete them, and, in the config/packages/prod directory, create a new api_platform.yaml file. Inside, start with api_platform: then paste.

enable_docs: false
enable_entrypoint: false

If we changed to the prod environment and rebuilt the cache, we'd be done!

But instead... I'm going to comment this out... for two reasons. First, I like the documentation, I like the machine-readable documentation and I like the "entrypoint": the documentation homepage. And second, more importantly, if you want to hide your documentation so that nobody will use your API, that's a bad plan. That's security through obscurity. If your API lives out on the web, you need to assume people will find it and you need to properly secure it. Hey! That's the topic of this tutorial!

Rebuild the cache one more time.

At the end of the day, if you're ok keeping the machine-readable docs and the entrypoint stuff, but you really don't want to expose the pretty HTML docs, you could always create an event subscriber on the kernel.request event - now called the RequestEvent in Symfony 4.3 - and, if the URL is /api and the request format is HTML, return a 404.


You can see an example here: https://bit.ly/2YmR6Uh

Ok, let's get into the real action: let's start figuring out how we're going to let users of our API log in.