HTTP headers for the responsible developer
I have been trying to explain the importance of HTTP headers to some younger/junior devs I am working with. I have noticed that headers are often considered to be 'too technical' or even 'old tech'.I'm going to recommend them to read this, but I do think I need to explain a couple of things that the article is not clear about:- Be sure that you understand the concept of HSTS! Simply copy/pasting the example from this article will completely break subdomains that are not HTTPS enabled and preloading will break it permanently. I wish the authors made that more clear. Don't use includesubdomains and preload unless you know what you are doing. Scott Helme also did a great article about this [0].- CSP can be really hard to set up. For instance: if you include google analytics, you need to set a script-src and a img-src. The article does a good job of explaining you should use CSP monitoring (I recommend sentry), but it doesn't explain how deceptive it can be. You'll get tons of reports of CSP exceptions caused by browsers plugins that attempt to inject CSS or JS. You must learn to distinguish which errors you can fix, and which are out of your control.- Modern popular frontend frameworks will be broken by CSP as they rely heavily on injecting CSS (a concept known as JSS or 'styled components'). As these techniques are often adopted by less experienced devs, you'll see many 'solutions' on StackOverflow and Github that you should set unsafe-inline in your CSP. This is bad advise as it will bascially disable CSP! I have attempted to raise awareness in the past but I always got the 'you're holding it wrong' reply (even on HN). The real solution is that your build system should separate the CSS from JS during build time. Not many popular build systems (such as create-react-app) support this.- Cache control can be really hard too. If you don't have time to fiddle with these settings, I recommend using a host like Netlify, they seem to do a proper job at caching in my experience.[0] https://scotthelme.co.uk/tag/hsts-preload/edit: typos