The Fly Blog

News, tips, and tricks from the team at Fly

11 min

Livebook is a secret weapon for documentation

Every application has that core, most important thing that it does. It is the reason the application exists. It's that central idea that everything else is there to support. A major hurdle for new developers joining a project can be understanding ...

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17 min

Hooking Up Fly Metrics

We’ve written a bit, for a general audience, about how Fly collects and manages metrics. If you’re just sort of generally interested in metrics and observability, go read that first. Meanwhile, if you’re a Fly user, or considering becoming such a...

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16 min

Fly's Prometheus Metrics

We should talk a bit about metrics and measurement and stuff, because they’re how we all know what’s going on. There’s two reasons we’ve written this post. The first is just that we think this stuff is interesting, and that the world can always us...

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10 min

Building a Distributed Turn-Based Game System in Elixir

One of the best things about building web applications in Elixir is LiveView, the Phoenix Framework feature that makes it easy to create live and responsive web pages without all the layers people normally build. Many great Phoenix LiveView exampl...

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20 min

Docker without Docker

Even though most of our users deliver software to us as Docker containers, we don’t use Docker to run them. Docker is great, but we’re high-density multitenant, and despite strides, Docker’s isolation isn’t strong enough for that. So, instead, we...

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16 min

The 5-hour CDN

The term "CDN" ("content delivery network") conjures Google-scale companies managing huge racks of hardware, wrangling hundreds of gigabits per second. But CDNs are just web applications. That's not how we tend to think of them, but that's all the...

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14 min

SSH and User-mode IP WireGuard

But Fly is kind of an odd duck. We run hardware in data centers around the world, connected to the Internet via Anycast and to each other with a WireGuard mesh. We take Docker-type containers from users and transmogrify them into Firecracker micro...

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7 min

Elixir is amazing – coincidentally, we're hiring Elixir dev advocates

Fly is a hosting platform for applications. Our users give us containers; we transmute them into fleets of Firecracker micro-VMs and run them on a WireGuard-backed Anycast network that runs application code close to users, anywhere in the world. D...

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13 min

Persistent Storage and Fast Remote Builds

If you’ve been keeping up with us at Fly, you may be picking up on a bit of a narrative with us. Fly launched, in the long-long-ago, with a somewhat narrow use case. We took containers from our customers and transmogrified them into fleets of Fire...

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12 min

The Tokio Upgrade from 0.2 to 1.x

At Fly.io, we run a Rust-based load-balancer which handles almost all of our traffic. It stands on the shoulders of Tokio and Hyper. When the Tokio team announced 0.3 and then 1.0, we figured we'd have to upgrade sooner than later to access relate...

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19 min

You should know about Server-Side Request Forgery

This is a post about the most dangerous vulnerability most web applications face, one step that we took at Fly to mitigate it, and how you can do the same. Server-side request forgery (SSRF) is application security jargon for “attackers can get ...

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17 min

The January 2021 Fly ChangeLog

If you missed 2020, lucky you, to get you all caught up, here's our Previously On Fly segment. Caught up? Good. And now here is the Fly ChangeLog, covering the end of December 2020 to January 2021. 6PN Networking and IPv6 WireGuard VPNsLet your a...

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