HTTP : The headers we want

The headers we want” is a very simple, straight to the point blog post on the Fastly blog.  Unlike many other more generic articles on the subject, it doesn’t try to explain the meaning of every HTTP header out there, and it doesn’t go into deep theory or the meaning of life, the universe and everything.

Instead it tells you plain and clear which headers should be emitted by your website or web application.  And these cover everything from the usual Content-Type and Content-Length, all the way down to the CORS and Server-Timing.

Once the basic functionality of your website or web application is done and out of the way, this blog post comes in handy with the specific best practices to make your site more secure and much faster.

For more on the same subject, have a look at “The headers we don’t want” in the same blog.

Let’s Encrypt now supports wildcard certificates

Here are some very exciting news from Let’s Encrypt:

We’re pleased to announce that ACMEv2 and wildcard certificate support is live! With today’s new features we’re continuing to break down barriers for HTTPS adoption across the Web by making it even easier for every website to get and manage certificates.

ACMEv24.0k is an updated version of our ACME protocol which has gone through the IETF standards process, taking into account feedback from industry experts and other organizations that might want to use the ACME protocol for certificate issuance and management some day.

Wildcard certificates5.1k allow you to secure all subdomains of a domain with a single certificate. Wildcard certificates can make certificate management easier in some cases, and we want to address those cases in order to help get the Web to 100% HTTPS. We still recommend non-wildcard certificates for most use cases.

Wildcard certificates are only available via ACMEv2. In order to use ACMEv2 for wildcard or non-wildcard certificates you’ll need a client that has been updated to support ACMEv28.5k. It is our intent to transition all clients and subscribers to ACMEv2, though we have not set an end-of-life date for our ACMEv1 API yet.

Additionally, wildcard domains must be validated using the DNS-01 challenge type. This means that you’ll need to modify DNS TXT records in order to demonstrate control over a domain for the purpose of obtaining a wildcard certificate.

Nginx 1.13.9 and HTTP/2 Server Push

Here are some very exciting news from the Nginx front lines: HTTP/2 Server Push is now available in the latest and greatest Nginx 1.13.9, which was released yesterday!

Server Push was one of the most exciting features for me in all of the HTTP/2 specification.  But I wasn’t quite sure how it will be implemented, and, most importantly, how it can be made easily available to the web developers, who are often few levels removed from the web server configuration.  I think Nginx solves the problem quite elegantly.

On the configuration level, “location” directives are often available to the web developers withing the virtual host / server.  But for those who can’t use those or don’t want to mess around with the configuration files, an even easier option is available – Link HTTP header.

I’m sure this will soon be widely supported in all the major libraries and frameworks, much like HTTP cookies are.   Great times ahead!

HTTPlug – The HTTP client abstraction for PHP

HTTPlug is an HTTP client abstraction for PHP.  Using this library you can decouple your code from the specifics of the HTTP implementation in your client of choice, and can also easily switch between different clients, like cURL, Guzzle, and so on.

HTTPlug also supports pluggable functionality, so you can expand or shrink as needed by your application.  Some examples of plugins include request / response logging and authentication.

Secure Headers – a PHP library for easier management of browser security features

Modern browsers offer a variety of security mechanisms for web developers.  Unfortunately, some of these aren’t so easy to manage.  One needs a deep understanding of the functionality as well as theory behind.  Secure Headers is a library that makes all that work a lot easier for PHP developers.  Here are some of the features:

  • Add/remove and manage headers easily
  • Build a Content Security Policy, or combine multiple together
  • Content Security Policy analysis
  • Easy integeration with arbitrary frameworks (take a look at the HttpAdapter)
  • Protect incorrectly set cookies
  • Strict mode
  • Safe mode prevents accidental long-term self-DOS when using HSTS, or HPKP
  • Receive warnings about missing, or misconfigured security headers

Spellbook of Modern Web Dev

Spellbook of Modern Web Dev is a collection of 2,000+ carefully selected links to resources on anything web development related.  It covers subjects from Internet history and basics of HTML, CSS, and Javascript, all the way to tools, libraries and advanced usage of web technologies, and more; from network protocols and browser compatibility to development environments, containers, and ChatOps.

  • This document originated from a bunch of most commonly used links and learning resources I sent to every new web developer on our full-stack web development team.
  • For each problem domain and each technology, I try my best to pick only one or a few links that are most important, typical, common or popular and not outdated, base on the clear trendspublic data and empirical observation.
  • Prefer fine-grained classifications and deep hierarchies over featureless descriptions and distractive comments.
  • Ideally, each line is a unique category. The ” / “ symbol between the links means they are replaceable. The “, “symbol between the links means they are complementary.
  • I wish this document could be closer to a kind of knowledge graph or skill tree than a list or a collection.
  • It currently contains 2000+ links (projects, tools, plugins, services, articles, books, sites, etc.)

On one hand, this is one of the best single resources on the topic of web development that I’ve seen in a very long time.  On the other hand, it re-confirms my belief in “there is no such thing as a full-stack web developer”.  There’s just too many levels, and there’s too much depth to each level for a single individual to be an expert at.  But you get bonus points for trying.

HTTPS on Stack Overflow: The End of a Long Road

Way too often I hear rants from random people (unfortunately, many of them are also from the IT industry, with the deep understanding of the underlying issues) complaining about why company X or product Y doesn’t implement this or that feature.  As someone who has been involved a dozens, if not hundreds, of projects, I pretty much always can think of a number of reasons why even seemingly the simplest of features aren’t implemented for years.  These can vary from business side of things – insufficient budgets, strategic goals, and the like – to technical, such as architectural limitations, insufficient expertise, insufficient resources, etc.

One of the recent frequent rant that keeps coming up is “Why don’t they just enable HTTPS?”.  Again, as someone being involved in HTTPS setup for several different environments I can think of a number of reasons why.  SSL certificates used to cost money and were quite cumbersome to install until very recently.  Thanks to Let’s Encrypt effort, SSL certificates are now free and quite easy to issue and renew.  But that’s only part of the problem.  Enabling HTTPS requires infrastructural changes, and the more complex your infrastructure, the more changes are needed.  Just think of a few points here – web server configuration (especially when you have multiple web servers, with varied software (Apache, Nginx, IIS) and varied versions of that software), load balancers, web application firewalls, reverse proxies, caching servers, and so on.

Apart from the infrastructural changes, HTTPS often needs changes on the application level.  Caching, cookies, headers, making sure that all your resources are HTTPS-only, redirects, and the like.

All of the above issues are multiplied by a gadzillion, when your project is publicly available, used by tonnes of people, and provides embeddable content or APIs to third-party (hello, backward compatibility).

This is not to mention that HTTPS itself is a complex subject, not well understood by even the most experienced system administrators and developers.  There are different protocols and versions (SSL vs. TLS), cipher suites, handshakes, and protocol details.  Just have a look at the variety of checks and the report length done by Qualys’ SSL Labs Server Test.  Even giants like Google, who employ thousands of smart people, can’t get it all right.

But for some reason, people either don’t know or prefer to ignore all this complexities, and whine and cry anyway.

Recently, Stack Overflow – a well known collection of sites on a variety of technical subjects, has completed the migration to HTTPS everywhere.  These are also people with a lot of knowledge and expertise and with access to all the information.  Just have a look at their long way, which took not months, but years: HTTPS on Stack Overflow: The End of a Long Road.

Today, we deployed HTTPS by default on Stack Overflow. All traffic is now redirected to https:// and Google links will change over the next few weeks. The activation of this is quite literally flipping a switch (feature flag), but getting to that point has taken years of work. As of now, HTTPS is the default on all Q&A websites.

We’ve been rolling it out across the Stack Exchange network for the past 2 months. Stack Overflow is the last site, and by far the largest. This is a huge milestone for us, but by no means the end. There’s still more work to do, which we’ll get to. But the end is finally in sight, hooray!

So next time you are about to start crying about somebody not having feature X or Y, just give it a minute first.  Try to imagine what goes on on the other side.  You aren’t the only one with low budgets, pressing deadlines, insufficient knowledge, bad colleagues and horrible bosses…

Using the Strict-Transport-Security header

Julia Evans has an excellent write-up on “Using the Strict-Transport-Security header” – what it is, why you’d want to use it, and what are some of the consequences of using one.

As always with her blog posts, this one is very focused on one particular subject, easy to read, and explains things simply, so that the reader’s technical level is always irrelevant (OK, OK, you do need a basic understanding of how HTTP works, but not more than that).

HAProxy SNI

HAProxy SNI” is pure gold! If you want to have a load balancer for HTTPS traffic, without managing SSL certificates on the said load balancer, there is a way to do so.

The approach is utilizing the Server Name Indication (SNI) extension to the TLS protocol.  I knew about it and I was already using it on the web server side, but it didn’t occur to me that it’ll be utilized on the load balancer.  Here’s the configuration bit:

frontend https *:443
  description Incoming traffic to port 443
  mode tcp
  tcp-request inspect-delay 5s
  tcp-request content accept if { req_ssl_hello_type 1 }
  use_backend backend-ssl-foobar if { req_ssl_sni -i foobar.com }
  use_backend backend-ssl-example if { req_ssl_sni -i example.com }
  default_backend backend-ssl-default

The above will make HAProxy listen on port 443, and then send all traffic for foobar.com to one backend, all traffic for example.com to another backend, and the rest to the third, default backend.