Category Archives for "CloudFlare"

Managing DNS Records For The People With Cloudflare Apps

Managing DNS Records For The People With Cloudflare Apps

DNS records are hard.  Many people, even the technically competent, don’t understand more than the basics.

Managing DNS Records For The People With Cloudflare Apps

I'll speak for myself — as someone who always learned just enough about DNS to get it working, then immediately forgot everything until the next time it broke. It was a vicious cycle until I convinced myself to learn it in depth.  Meanwhile, non-technical folks wisely avoid meddling in such dangerous affairs all together.

Surely, there must be a better way (this is a blog post after all).

Every day, thousands of Cloudflare users add DNS records to their Internet properties to configure awesome tools like G Suite, Shopify, Wordpress, Ghost, and thousands of others.  A new Cloudflare Apps feature allows apps to automatically set up and manage configurable DNS records on more than 12 million registered domains on the Cloudflare network. In short, Cloudflare Apps are here to alleviate the Internet’s collective DNS woes.

Gone are the days of tribulating over whether it’s A or CNAME you should set.  Gone are the days of puzzling between A and AAAA records while wondering what the heck happened to AA and AAA records?  Unload your DNS dysphoria onto highly trained developers experienced at explicating these Continue reading

Traffic Acceleration with Cloudflare Mobile SDK

Traffic Acceleration with Cloudflare Mobile SDK

We’re excited to announce early access for Traffic Acceleration with Cloudflare Mobile SDK. Acceleration uses novel transport algorithms built into the SDK to accelerate apps beyond the performance they would see with TCP. Enabling Acceleration through the SDK reduces latency, increases throughput, and improves app user experiences.

A year ago, we launched Cloudflare Mobile SDK with a set of free features focused on measuring mobile app networking performance. Apps are dependent on network connectivity to deliver their app’s user experiences, but developers have limited visibility into how network connectivity is impacting app performance. Integrating the Mobile SDK allows developers to measure and improve the speed of their app’s network interactions.

How it works

Mobile applications interact with the Internet to do everything — to fetch the weather, your email, to step through a check out flow. Everything that makes a smartphone magical is powered by a service on the Internet. How quickly those network interactions happen is dictated by two things: how large the payloads are for the given request/response, and what the available link bandwidth is.

Payload size is mostly application specific: a shopping app is going to request product images and similar medium sized assets, while a stock Continue reading

How my team wrote 12 Cloudflare apps with fewer than 20 lines of code

How my team wrote 12 Cloudflare apps with fewer than 20 lines of code

This is a guest post by Ben Ross. Ben is a Berkeley PhD, serial entrepreneur, and Founder and CTO and, where he spends his days helping small businesses grow online.

I like my code the same way I like my team of POWr RangersDRY.

And no, I don’t mean dull and unexciting! (If you haven’t heard this acronym before, DRY stands for Don’t Repeat Yourself, the single most important principle in software engineering. Because, as a mentor once told me, “when someone needs to re-write your code, at least they only need to do it once.”)

At POWr, being DRY is not just a way to write code, it’s a way of life. This is true whether you’re an Engineer, a Customer Support agent, or an Office Manager; if you find you’re repeating yourself, we want to find a way to automate that repetition away. Our employees’ time is our company’s most valuable resource. Not to mention, who wants to spend all day repeating themselves?

We call this process becoming a Scaled Employee. A Scaled Employee leverages their time and resources to make a multifold impact compared to an average employee in their Continue reading

More consistent LuaJIT performance

More consistent LuaJIT performance

This is a guest post by Laurence Tratt, who is a programmer and Reader in Software Development in the Department of Informatics at King's College London where he leads the Software Development Team. He is also an EPSRC Fellow.

A year ago I wrote about a project that Cloudflare were funding at King's College London to help improve LuaJIT. Our twelve months is now up. How did we do?

The first thing that happened is that I was lucky to employ a LuaJIT expert, Thomas Fransham, to work on the project. His deep knowledge about LuaJIT was crucial to getting things up and running – 12 months might sound like a long time, but it soon whizzes by!

The second thing that happened was that we realised that the current state of Lua benchmarking was not good enough for anyone to reliably tell if they'd improved LuaJIT performance or not. Different Lua implementations had different benchmark suites, mostly on the small side, and not easily compared. Although it wasn't part of our original plan, we thus put a lot of effort into creating a larger benchmark suite. This sounds like a trivial job, but it isn't. Many programs make Continue reading

OAuth Auth Server through Workers

OAuth Auth Server through Workers

Let’s pretend I own a service and I want to grant other services access to my service on behalf of my users. The familiar OAuth 2.0 is the industry standard used by the likes of Google sign in, Facebook, etc. to communicate safely without inconveniencing users.

Implementing an OAuth Authentication server is conceptually simple but a pain in practice. We can leverage the power of Cloudflare Worker to simplify the implementation, reduce latency, and segregate our service logic from the authentication layer.

For those unfamiliar with OAuth, I highly recommend reading a more in depth article.

The steps of the OAuth 2.0 workflow are as follows:

  1. The consumer service redirects the user to a callback URL that was setup by the auth server. At this callback URL, the auth server asks the user to sign in and accept the consumer permissions requests.
  2. The auth server redirects the user to the consumer service with a code.
  3. The consumer service asks to exchange this code for an access token. The consumer service validates their identity by including their client secret in the callback URL.
  4. The auth server gives the consumer the access token.
  5. The consumer service can now use Continue reading

The truth about Black Friday and Cyber Monday

The truth about Black Friday and Cyber Monday

At Cloudflare we handle a lot of traffic on behalf of our customers. Something we all see and hear a lot about at this time of year are Black Friday (23 November this year) and Cyber Monday (26 November) - but just how important are these days on the Internet?

The truth about Black Friday and Cyber Monday
Black Friday by Per-Olof Forsberg, license: CC BY 2.0

To try and answer this question, we took a look at anonymised samples of HTTP requests crossing our network. First of all, let’s look at total page views from across our global network from the last few weeks and see if we can spot Black Friday and Cyber Monday:

The truth about Black Friday and Cyber Monday
All page views

So this is total page views by day (UTC) from November 19 (a week before Cyber Monday) until Monday December 3. Other than follow-the-sun fluctuations in a repeating daily pattern, each whole day is pretty similar in shape and size compared to the last. Black Friday and Cyber Monday aren’t visible in overall traffic patterns.

Get specific

We have a very diverse set of customers across 12 million domain names and not all of them are selling products or doing so directly online. To identify those websites Continue reading

A new look on your Cloudflare dashboard

A new look on your Cloudflare dashboard

Building a great customer experience is a top priority here at Cloudflare. Over the last week, we have been  slowly rolling out an improvement to our customer dashboard - specifically the zone overview page. We are now ready to share the new dashboard with everyone.

A new look on your Cloudflare dashboard
The new Cloudflare dashboard

Many of the changes you’ll notice first were driven directly by customer feedback. We’ve heard time and time again that site owners would like better visibility of their key analytics, and for it to be easier to apply certain common settings changes. This new dashboard provides both, with a snapshot of several of your key analytics, and a new toolkit area for easy access to key functions. This page has also been redesigned from top to bottom for responsiveness across various devices and screen widths.

Even more interesting is all the work under-the-hood that went into making this release and how it sets the stage for improvements to our customer experience as we look ahead to 2019. This is one of the first pieces of production Product work shipped using our new prototyping framework. We will soon be sharing details of the design systems work that underlies the new experience on Continue reading

EU Terrorist Content Online proposal – political haste and unintended consequences

EU Terrorist Content Online proposal – political haste and unintended consequences
Photo by Sara Kurfeß / Unsplash
EU Terrorist Content Online proposal – political haste and unintended consequences

In September, the European Commission presented a legislative proposal to address the removal of terrorist content online. There has been significant political pressure, particularly as the EU elections of 2019 approach, towards internet companies taking on increased responsibility in the area of terrorist propaganda online. This proposal would be a marked move from various voluntary initiatives taken up by some social media companies in recent times towards a legal responsibility framework for many.  

While appreciating the concerns around terrorism, Cloudflare is not only troubled by the late presentation of this proposal – which leaves inadequate time for a thorough review before this EU legislative term expires – but also much of the substance. Along with others such as CDT, GSMA/ETNO and Mozilla, we have significant concerns around the legal implications, practical application and possible unintended consequences of the proposal, some of which we outline below. Furthermore, we believe that little evidence has been presented as to the necessity of the proposed measures.

Concerns and shortcomings

The Commission’s proposal does not account for the complexity and range of information society services having a storage component - not all services have the same Continue reading

How well do you know website performance?

How well do you know website performance?
How well do you know website performance?

How quickly did this blog post load? Did you happen to notice?

Most website visitors do notice that sort of thing, even if they don't realize it consciously. In fact, virtually all visitors have strong opinions about how quickly a website should load, how responsive it should be, and how often it should go down (preferably, never). Most users strongly prefer webpages that take under 5 seconds to load, and they're much more likely to leave without buying products or reading content if a page takes too long to render.

Everyone should understand how to keep websites fast

Part of the Cloudflare mission is to make the Internet better by helping it perform better. One way we are delivering on our mission is by sharing easy-to-read educational content to assist anyone with a web property.

We recently launched a performance-themed Learning Center: a series of educational articles on why performance matters, the factors affecting performance, and some of the best practices for making websites faster. Check out the Performance Learning Center!

This Learning Center is for anyone who wants to really do a deep dive into the complex topic of website performance, no matter what their technical background Continue reading

Cloudflare Apps Fund 2.0

Today we are launching the second iteration of the Cloudflare App Developer Fund.

This is an investment fund started in partnership with Venrock, Pelion Venture Partners, and New Enterprise Associates. We created the fund to provide developers with resources so that they can build apps using the Cloudflare network and our serverless product, Workers, which enables developers to create applications without configuring or maintaining infrastructure. The goal is to fuel a new economy that grows into a thriving ecosystem so that developers’ serverless innovations can enjoy commercial success.  

Cloudflare Apps with Workers allows developers to package Workers, delivering new worker-powered experiences to Cloudflare customers, all within a few clicks via Cloudflare Apps.

Our CTO, John Graham-Cumming talks about it in a recently recorded video:

In short, Cloudflare is looking for apps that will advance our mission to help build a better Internet: one that is safe, fast and reliable.   We are seeking out apps that have a clear vision, delight customers by the ease of use and align with our vision. Having already seen multiple use cases around custom application security, data loss prevention, and bot mitigation, we can’t wait to see what else you come up Continue reading

Logs from the Edge

Logs from the Edge

With Cloudflare Workers, our JavaScript environment at the edge, it is possible to send traffic logs to arbitrary locations. In this post we are going to discuss an example Worker implementation on how to achieve this. So if you are building or maintaining your own traffic logging/analytics environment, read on.

To build the underlying script we are going to leverage sub requests. Sub requests, which can be spawned from the initial HTTP/S request, can be used to aggregate and compose a response from several back end services, or, like in the example discussed here, to post data to a specific endpoint. Sub requests can be made asynchronously and after the initial request has been fully served to avoid adding unnecessary latency to the main request.

Logs from the Edge

The Worker Code

In this example we assume an Elastic stack has been set up at and has been configured to receive via HTTP/S PUT requests a number of fields for each log line. The full script that we are going to look at can be found below:

addEventListener('fetch', event => {

async function fetchAndLog(event) {
  const response = await fetch(event.request);
  event.waitUntil(logToElk(event.request, response));
  return response;
 Continue reading

Know your SCM_RIGHTS

As TLS 1.3 was ratified earlier this year, I was recollecting how we got started with it here at Cloudflare. We made the decision to be early adopters of TLS 1.3 a little over two years ago. It was a very important decision, and we took it very seriously.

It is no secret that Cloudflare uses nginx to handle user traffic. A little less known fact, is that we have several instances of nginx running. I won’t go into detail, but there is one instance whose job is to accept connections on port 443, and proxy them to another instance of nginx that actually handles the requests. It has pretty limited functionality otherwise. We fondly call it nginx-ssl.

Back then we were using OpenSSL for TLS and Crypto in nginx, but OpenSSL (and BoringSSL) had yet to announce a timeline for TLS 1.3 support, therefore we had to implement our own TLS 1.3 stack. Obviously we wanted an implementation that would not affect any customer or client that would not enable TLS 1.3. We also needed something that we could iterate on quickly, because the spec was very fluid back then, and also something Continue reading

L4Drop: XDP DDoS Mitigations

L4Drop: XDP DDoS Mitigations

Efficient packet dropping is a key part of Cloudflare’s distributed denial of service (DDoS) attack mitigations. In this post, we introduce a new tool in our packet dropping arsenal: L4Drop.

L4Drop: XDP DDoS Mitigations
Public domain image by US Air Force

We've written about our DDoS mitigation pipeline extensively in the past, covering:

  • Gatebot: analyzes traffic hitting our edge and deploys DDoS mitigations matching suspect traffic.
  • bpftools: generates Berkeley Packet Filter (BPF) bytecode that matches packets based on DNS queries, p0F signatures, or tcpdump filters.
  • Iptables: matches traffic against the BPF generated by bpftools using the xt_bpf module, and drops it.
  • Floodgate: offloads work from iptables during big attacks that could otherwise overwhelm the kernel networking stack. Incoming traffic bypasses the kernel to go directly to a BPF interpreter in userspace, which efficiently drops packets matching the BPF rules produced by bpftools.

Both iptables and Floodgate send samples of received traffic to Gatebot for analysis, and filter incoming packets using rules generated by bpftools. This ends up looking something like this:

L4Drop: XDP DDoS Mitigations
Floodgate based DDoS mitigation pipeline

This pipeline has served us well, but a lot has changed since we implemented Floodgate. Our new Gen9 and ARM servers use different network Continue reading

Working out Backend Knots and Building Routers (Austin Real World Serverless Video Recap)

Working out Backend Knots and Building Routers (Austin Real World Serverless Video Recap)

I work in Developer Relations at Cloudflare and I'm fortunate to have top-notch developers around me who are willing to share their knowledge with the greater developer community. I produced a series of events this autumn called Real World Serverless at multiple locations around the world and I want to share the recorded videos from these events.

Our Austin Real World Serverless event (in partnership with the ATX Serverless User Group Meetup) included two talks about Serverless technology featuring Victoria Bernard and Preston Pham from Cloudflare. They spoke about working out backend knots with Workers and building a router for the great good.

About the talks

Working out Backend Knots with Workers - Victoria Bernard (0:00-15:19)

Cloudflare Workers is a platform the makes serverless development and deployment easier than ever. A worker is a script running between your clients' browsers and your site's origin that can intercept requests. Victoria went over some popular use cases of how proxy workers can dramatically improve a site's performance and add functionality that would normally require toying with complicated back-end services.

Build a Router for Great Good - Preston Pham (15:20-33:53)

Serverless computing is great, but requires routing or some kind of API Continue reading

My Second Cloudflare Company Retreat

My Second Cloudflare Company Retreat

Last week, 760 humans from Singapore, London, Beijing, Sydney, Nairobi, Austin, New York, Miami, Washington DC, Warsaw, Munich, Brussels, and Champaign reunited with their San Francisco counterparts for our 9th annual Cloudflare company retreat in the San Francisco Bay Area. The purpose of the company retreat is to bring all global employees together under one roof to bond, build bridges, have fun, and learn – all in support of Cloudflare’s mission to help build a better Internet.

It’s easy to write off corporate retreats as an obligatory series of meetings and tired speeches, but Cloudflare’s retreats are uniquely engaging, personalized, fun, and inspiring. Having grown with Cloudflare over the last year (I started just before our 2017 retreat), I wanted to share some of my experiences to highlight Cloudflare’s incredible culture.

The office was buzzing with different languages and laughter as people hugged and shook hands for the first time after working online together for a year or more. Everyone’s Google calendar looked like a rainbow as we each mined for white space to squeeze in those coveted 1:1s, all-hands presentations, and bowling offsites with our global colleagues.  The buses and Google chats felt like summer camp, with people claiming Continue reading

Every 7.8μs your computer’s memory has a hiccup

Every 7.8μs your computer’s memory has a hiccup

Every 7.8μs your computer’s memory has a hiccup
Modern DDR3 SDRAM. Source: BY-SA/4.0 by Kjerish

During my recent visit to the Computer History Museum in Mountain View, I found myself staring at some ancient magnetic core memory.

Every 7.8μs your computer’s memory has a hiccup
Source: BY-SA/3.0 by Konstantin Lanzet

I promptly concluded I had absolutely no idea on how these things could ever work. I wondered if the rings rotate (they don't), and why each ring has three wires woven through it (and I still don’t understand exactly how these work). More importantly, I realized I have very little understanding on how the modern computer memory - dynamic RAM - works!

Every 7.8μs your computer’s memory has a hiccup
Source: Ulrich Drepper's series about memory

I was particularly interested in one of the consequences of how dynamic RAM works. You see, each bit of data is stored by the charge (or lack of it) on a tiny capacitor within the RAM chip. But these capacitors gradually lose their charge over time. To avoid losing the stored data, they must regularly get refreshed to restore the charge (if present) to its original level. This refresh process involves reading the value of every bit and then writing it back. During this "refresh" time, the memory is busy and it can't perform normal operations Continue reading

Serverless Progressive Web Apps using React with Cloudflare Workers

Let me tell you the story of how I learned that you can build Progressive Web Apps on Cloudflare’s network around the globe with one JavaScript bundle that runs both in the browser and on Cloudflare Workers with no modification and no separate bundling for client and server. And when registered as a Service Worker, the same JavaScript bundle will turn your page into a Progressive Web App that doesn’t even make network requests. Here's how that works...

"Any resemblance to actual startups, living or IPO'd, is purely coincidental and unintended" - @sevki

A (possibly apocryphal) Story

I recently met up with some old friends in London who told me they were starting a new business. They did what every coder would do... they quickly hacked something together, bought a domain, and registered the GitHub org and thus Buzzwords was born.

The idea was simple: you could feed the name of your application into a machine learning model and it would generate the configuration files for your deployment for various container orchestrators. They achieved this by going through millions of deployment configurations and training a linear regression model by gamifying quantum computing because blockchain, or something (I told you this Continue reading

Fast Google Fonts with Cloudflare Workers

Fast Google Fonts with Cloudflare Workers

Google Fonts is one of the most common third-party resources on the web, but carries with it significant user-facing performance issues. Cloudflare Workers running at the edge is a great solution for fixing these performance issues, without having to modify the publishing system for every site using Google Fonts.

This post walks through the implementation details for how to fix the performance of Google Fonts with Cloudflare Workers. More importantly, it also provides code for doing high-performance content modification at the edge using Cloudflare Workers.

Google fonts are SLOW

First, some background. Google Fonts provides a rich selection of royalty-free fonts for sites to use. You select the fonts you want to use, and end up with a simple stylesheet URL to include on your pages, as well as styles to use for applying the fonts to parts of the page:

<link href="|Roboto+Slab"
body {
 font-family: 'Open Sans', sans-serif;
h1 {
 font-family: 'Roboto Slab', serif;

Your visitor’s browser fetches the CSS file as soon as the HTML for the page is available. The browser will request the underlying font files when the browser does layout for the page and discovers that it needs Continue reading

My time as an intern (thus far)

My time as an intern (thus far)

It has been over three months since I started as a marketing intern at Cloudflare. Even before joining the Cloudflare team, I enjoyed reading the technical blog posts about Cloudflare’s use cases and solutions, as well as the inclusive and creative culture. Educating the world about the threats we face on the Internet is something that I found truly valuable. I figured that I would give my own spin on what it’s like to join and work at Cloudflare by writing a blog post too.

Chapter 1: The Path towards the Orange Cloud

My time as an intern (thus far)
Photo by alexander milo / Unsplash

Before starting as a freshman in university, I created an online portfolio for my photography. It has been a passion of mine for about 9 years. I tried a multitude of platforms but none afforded me the aesthetic control that I wanted. The only solution was to build and host my own site. I started learning HTML/CSS, a bit of JavaScript and jQuery and so on.

This led to me using the Koken CMS, and hosting it on DigitalOcean in a Docker container. What was left was SSL/TLS encryption and a CDN (my friends in Europe find the loading times unbearable). Continue reading

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