Screaming in the Cloud
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Bringing FreeBSD to EC2 with Colin Percival
About Colin Percival
Colin is the founder of Tarsnap, a secure online backup service which combines the flexibility and scriptability of the standard UNIX "tar" utility with strong encryption, deduplication, and the reliability of Amazon S3 storage. Having started work on Tarsnap in 2006, Colin is among the first generation of users of Amazon Web Services, and has written dozens of articles about his experiences with AWS on his blog.
Colin has been a member of the FreeBSD project for 15 years and has served in that time as the project Security Officer and a member of the Core team; starting in 2008 he led the efforts to bring FreeBSD to the Amazon EC2 platform, and for the past 7 years he has been maintaining this support, keeping FreeBSD up to date with all of the latest changes and functionality in Amazon EC2.In his spare time, Colin serves as an alumni representative on the Senate of his alma mater, Simon Fraser University, where he frequently brings a perspective from the world of startups to the ivory tower.


Links Referenced
Transcript
Announcer: Hello, and welcome to Screaming in the Cloud with your host, Cloud Economist Corey Quinn. This weekly show features conversations with people doing interesting work in the world of cloud, thoughtful commentary on the state of the technical world, and ridiculous titles for which Corey refuses to apologize. This is Screaming in the Cloud.


Corey: This episode is brought to you by DigitalOcean, the cloud provider that makes it easy for startups to deploy and scale modern web applications with, and this is important to me, no billing surprises. With simple, predictable pricing that’s flat across 12 global data center regions and UX developers around the world love, you can control your cloud infrastructure costs and have more time for your team to focus on growing your business. See what businesses are building on DigitalOcean and get started for free at do.co/screaming. That’s D-O-Dot-C-O-slash-screaming and my thanks to DigitalOcean for their continuing support of this ridiculous podcast.


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Corey: Welcome to Screaming in the Cloud. I'm Corey Quinn. I'm joined this week by Colin Percival. Colin is the founder of Tarsnap, which is a secure online backup service, as well as having been a staple in the EC2 history for the one true operating system, FreeBSD. Colin, welcome to the show.


Colin: It’s good to be here.


Corey: So, let's start at the very beginning. What is a FreeBSD, for someone who might never have encountered such a thing in the wild?


Colin: FreeBSD, for people who have very little computing background I often say it's like Linux, but it's not Linux.


Corey: Oh, I bet that irritates some people.


Colin: I'm sure that does irritate some people, and I don't like it when people refer to FreeBSD as being other Linux, which EC2 still does in some places. But for people with somewhat more of a technical background, I say FreeBSD is Unix, and it's about as close as you can get to the natural successor to the original Unix.


Corey: So, once upon a time, back when I was first starting out in my career, I found myself at a university and FreeBSD was what I wound up single-handedly deploying, because of a few different failure modes. One, it turns out that when you have someone who pretty much bluffed their way through the technical interview, and then you give them carte blanche to deploy whatever they want, you get some strange things happening. Not that this was necessarily a bad decision. But, years later when the statute of limitations has run its course, I can now say the reason that I went in that direction was because I had a mentor who was very anti-Linux and very pro-FreeBSD and quite simply, he would help me if I had a FreeBSD question, but he would look down his nose at Linux. Therefore, I was pretty much in a position of, well, beggars can't be choosers. So, I made a full-throated endorsement of FreeBSD, rolled it out, and ran it for a year. Then I moved on to other jobs and haven't touched it in anger or in production ever since. But I still miss it 15 years later, or so.


Colin: That makes sense to me. To be honest, the reason that I started using FreeBSD was it was easier to install than OpenBSD.


Corey: The problem I ran into was that, I guess—how to frame this for someone who hasn't done a whole lot of work with either one? Because I tend to assume that you don't need to have a background as a Linux or Unix administrator to listen to this show and get something out of it. But from my perspective, it felt like FreeBSD was an environment where everything was very clearly ordered. Everything belonged in a certain place. There was a right way to do things. It didn't have a manual. It had a handbook that told you how to go through any aspect of the system. There was a start to it, a middle, an end, and it was great. Going from that to Linux felt like suddenly I'm living in the middle of barely organized chaos. And I kept waiting for that feeling to fade. It hasn’t. I’ll let you know if it ever does.


Colin: I don't know if I would say that in FreeBSD there is always one right way to do things. We have binary packages you can install, or you can build things in the ports tree if you prefer. You can even try to build your own binary packages if you want to build them, and then it's all done, just to make your life more complicated, for instance. I would say that FreeBSD is developed by people who try very hard to make sure that the options that they offer are good ones. And, sometimes that means there is one good option and we tell people this is what you do. Sometimes it means there are several good options and we tell people pick one of these options. But I will agree that in some other platforms, there are no clear good options, or there are many options which are not good ones, and people flounder and end up with things that are not good.


Corey: That's probably a fair way of assessing it. Now, back in the day when I was playing with these things, it was all on-premises hardware, I would say servers, but that's putting it generously. It turns out that when you have—and in this era, this was not an unreasonable operating system choice, but a bunch of desktops that were running Windows XP. And then, after three years, they were deprecated off the books and users wouldn't tolerate how badly they performed, you could then repurpose them, install a different operating system on that, and put it in your giant shelf of badly maintained servers. 


So, we had 15 mail servers running like that. One of the earlier projects that I had during my year, there was to rip a lot of that out, but I got to experience an awful lot of janky hardware, interestingly supported on a variety of operating systems. And a few years later, I wound up encountering you, but not knowing it at the time ‘till many years after the fact, because you were effectively one of the driving forces behind getting FreeBSD working on EC2 in the early days.


Colin: I would say in the early days, I was the person that decided this is something that should happen.


Corey: And happened it did. But I guess my question is, is what does it take to look at an existing offering like EC2, where you could ask what operating systems they supported, and back then the answer was, oh, both kinds, Windows, and Linux. And from there, okay, how do you go from having something like a, I guess, a Linux or Linux-y operating system, and then effectively doing a wholesale replacement of the OS, I guess, first, in a way that works, and secondly, ideally in a way that doesn't offend the purest sensibilities of a number of Unix aficionados?


Colin: Well, I want to just correct one thing you said there you said both kinds, Linux and Windows. In fact, when I first decided I wanted to get FreeBSD working, there was one version of Linux that was supported on EC2. And then, later they were both kinds, being CentOS and Ubuntu. It was actually a few years before Windows came along. And by that point, I was already trying and failing, in a wide variety of different ways, to get FreeBSD working.


Corey: Amazing. I guess that's one of those history lessons that I wound up avoiding by virtue of not being at all involved in the cloud back in those early days. But wow, it's not often that I wind up getting exposure to a trivia fact on AWS I didn't already know. Good work.


Colin: Well, I mean, there's a lot of interesting trivia from back then, like the fact that in the early paravirtualized days of EC2, you didn't just have a machine image you also had a kernel image and a RAM disk image. Because you couldn't just say whatever is on this disk, you had to give the paravirtualized Xen the kernel it was going to run, and Linuxes, at the time, needed a RAM disk with… something, I don't know exactly what, on it before it could load everything else off of the filesystem on disk.


Corey: Back in those days, there was the RAM disk, you had to pick what kernel you had to run through. I don't want to say that it was complicated or Byzantine, but there was a company, RightScale, back before they were acquired and no one heard from them ever again, where their entire business value was wrapping the EC2 API's into a front end dashboard that a human being could understand, and then charging a percentage of whatever you ran through it, which sounds ridiculous today, but pretty much everyone I knew, to a large part, back in 2008, 2009 was running through this just because it was so complicated to get up and running. The documentation wasn't there, and the folks who were super involved with it largely were themselves AWS employees, or effectively the next closest thing. How did you dive in and get started with something like that back in those days, where, effectively, it was the digital equivalent of rubbing two sticks together to make fire?


Colin: So, in some ways, it was easier to get started back then, because AWS was really small, and pretty much everybody inside Amazon, or inside AWS at least, knew what everybody else was doing in there. And they didn't have huge numbers of customers asking them for help. So, I sent an email to Jeff Barr. I said, “Hey, I want to get FreeBSD working on EC2.” And he wrote back to me and said, “Here's some people at Amazon you should talk to you.” And for the first few years of trying to get things working, pretty much all of my contacts at Amazon were going through Jeff Barr. 


I talked to him on Twitter and so on, but if I needed somebody, Jeff knows everybody. I just sent Jeff an email; he connects me with the right people. And the Amazon engineers were always incredibly enthusiastic. I got the feeling that Amazon as a corporate entity didn't really appreciate FreeBSD. The managers didn't know what FreeBSD was, except that they could tell they didn't have any customers using it. But all the engineers, they loved the idea of getting a different operating system running on their platform.


Corey: It seemed like it was almost a great hobbyist direction back then, in that people were excited to see what the potential use cases of the platform were because this was back in the day before you really had giant companies going all-in on this. Now, for that same level of excitement, people instead have to settle for watching me misuse Route 53 as a database or similar. But back in those days it was, is this even possible was the burning question in everyone’s mind. You proved that it was. And what astonishes me is now, years later, there is still a thriving FreeBSD offering on top of AWS. Is that entirely you? Is there a larger community behind it now? Is it officially supported by folks at Amazon?


Colin: So, the FreeBSD offering on AWS now is officially supported by the FreeBSD project. So, in the early days, it was me building disk images. And, at one point, about a two hour round trip time to test any things I needed to upload a 10-gigabyte disk image before I could boot it, and see where it failed to boot. 


These days, the FreeBSD release engineering team is doing all the builds, just as part of our standard release building process. Now, that's the actual building of the images. Making things work, that's a completely different matter. And there's been a lot of work, a little bit by me, but largely by other FreeBSD developers, in the early days working on Xen, dealing with new sorts of Xen devices we needed to handle. More recently, a lot of bug fixes on our NVMe driver because all the Nitro instances expose NVMe disks. Amazon—I was very happy to hear when they launched the Elastic Network Adapter a few years back, they had a Linux driver, and I got worried that they were going to pay people to port their Linux driver to FreeBSD. And, I mean, in FreeBSD, we’re used to, there's a Linux driver over there, go ahead and try to port it. Sometimes there's a Linux driver and here's some documentation for it. It's absolutely wonderful when we have a company actually present us with a FreeBSD driver, and Amazon paid for that to be done, and in fact, has been having people maintain it for us ever since.


Corey: So, other than hobbyists and you, who's using FreeBSD on top of AWS these days? Are there public reference customers? Is this mostly a bunch of hobbyists building interesting things? I mean, you're running an entire business on top of this, which is not nothing. But who's playing around in the space these days?


Colin: To be honest, I don't know exactly who is running FreeBSD on EC2. I can tell you that from the EC2 marketplace, we have around 3 or 4000 instances running that were launched through the Marketplace. I'm sure more far more than that, that were just launched by somebody copying and pasting the AMI ID into the console or onto the command line. There are companies that we know use FreeBSD, like NetApp. I would assume that some of their cloud offerings also run on FreeBSD because why would they not use the same platform for their cloud offerings? But large companies have been very reticent to talk to me about what it is that they're doing with FreeBSD on EC2. It's one of the things I really regret, not hearing from these large customers.


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Corey: That's always been one of the challenges I've seen in the FreeBSD universe, to be fair, is that because of the license is such—the BSD license is you can use the source code, you can do whatever you want to and you don't have to re-contribute any changes back, it becomes very uncertain to be able to attribute who is using this in any meaningful way. In fact, the only way that I was able to find FreeBSD jobs when I went looking was by looking specifically for the term FreeBSD in job descriptions. That's how I learned companies like for example, Juniper were big proponents of FreeBSD. But there was remarkably little representation in the common community-style circle.


Colin: That that definitely is an issue. The license being more generous and also, to be honest, the fact that the license is so brief. It does make it harder to identify who's using BSD code. If you buy a TV, and it comes with a copy of the GPL, it gives you some idea of what software is running it. BSD license, you might not even notice because it's half a page rather than 10 pages.


Corey: Yeah, when the entire license fits in a tweet, one starts to wonder.


Colin: Exactly. I don't think BSD license is quite that small, but same idea, yes. So, yeah, it is harder to tell who's running FreeBSD. As far as large companies using FreeBSD now, if you look at FreeBSD developers and where they work, I mean, it's clear—there are companies like Juniper—I don't know if they have FreeBSD developers right now, but they certainly had many in the past. Netflix, of course, has many FreeBSD developers and goes to conferences and talks about the work they're doing on FreeBSD, getting 200 gigabits per second of TLS throughput from their movie streaming devices. So, there certainly are large companies out there using FreeBSD, being open about the fact using FreeBSD, and contributing changes back. But I'm sure there are others out there that are quieter about it.


Corey: Which is very fair. So, let's talk instead, for a minute, about the company you actually run, because it turns out that volunteering your spare time to get FreeBSD working on EC2 is not, in fact, your primary vocation these days, you run a service called Tarsnap. What is Tarsnap?


Colin: Tarsnap—well, the slogan is, “Online backups for the truly paranoid.” It is an online backup service with a tar command-line frontend. And so, you type in a command that—actually it could just be a tar command except with the word Tarsnap in front instead of tar. And say you want to create an archive containing certain files or directories, it bundles those all up, it deduplicates them, it compresses them, and then it encrypts everything before it uploads it to the storage service, which is ultimately backed by Amazon S3.


Corey: Gotcha. So, you say that their backups are for the truly paranoid. Everyone likes to think of themselves as being paranoid with backups, but in my experience, everyone cares an awful lot about backups right after they really needed to care about backups. And even then, they are diligent about making sure that things back up but they never test a restore. So, it leads you to a fun place where backups for the truly paranoid mean different things for different folks. What does it mean for you?


Colin: So, I started this when I was a FreeBSD security officer, and as a FreeBSD security officer, I would get advance notice of security vulnerabilities that affected FreeBSD. So, problems in Sendmail, problems in bind, problems in OpenSSL. And at a certain point, I was looking at all the vulnerabilities I had sitting on my laptop waiting to be fixed because, of course, we always coordinate these disclosures. We pick some date so that everybody can log a patch at the same time. And I was thinking to myself, if somebody got their hands on my laptop, bad things could happen because they could exploit that one, and they could exploit that one, or they could [00:23:28 unintelligible] the vulnerability. 


And I thought to myself, “Wait a minute, if somebody's got their hands on my backups, we would be in trouble as well.” Now, like most people, I didn't really do very good backups at the time. But I then was thinking, “Well, if I start doing backups more often, than that means there's more copies of all this scary information sitting around somewhere. How do I do this securely?” So, I looked around at what I could find online in 2006, and they're really wasn't anything out there that I could trust to do backups securely. I was a FreeBSD security officer, I had quite a background in security and cryptography at that point. And just based on my expertise in the fields, I didn't trust what was out there. 


So, I asked around, some of my friends and posted on my blog, and I asked, “If I build this myself, would anybody else want to use it?” Lots of people said, “Yes, this is something we would pay for.” So, it happened I was looking for work at the time. I had a job offer from Google to go down to San Francisco and do research. But I wasn't [00:24:36 unintelligible] offer for a few reasons. So, I decided well, okay, I'll build it myself and see how it goes. So, it turns out it is very much a startup in the open-source tradition of scratching your own itch. I had a problem. Some of the people said that they have the same problem, so I decided to fix it.


Corey: And fix it you did. It's been around for a while. You have some very impressive name-brand customers who are publicly referenced on your site. Stripe is a, I guess the canonical example. If you take a look at how much they care about the sanctity of their backups, I don't feel like there's really enough words to express the answer to that question. If you get effectively the internet's payment systems data, there is disaster, and hellfire, and brimstone, and nothing looks the same tomorrow if that happens. So, it's obviously validated and tested by folks who take their workload seriously. I guess the question is, is why did you go down the path of A) using FreeBSD for this, and B) building it on top of EC2 instead of a bunch of different options that you could have potentially gone with?


Colin: So, in 2006, when I decided I wanted to do this, I knew—I mean, I'm a software guy. I knew that I did not want to be dealing with physical hard drives and I definitely didn't want to be driving down to the datacenter to swap out failed hard drives. So, I wanted something out there that could store the data for me and not lose it. S3 launched earlier that year, so I said to myself, “Okay, S3 sounds like the backend I want to use for this. And then, well, I need to have some code running in front of that. Oh, look, here's this Elastic Compute Cloud service that lets you have servers that are really close to S3 and can push bits in and out of S3, without paying any bandwidth costs.” So, it was just a natural connection there, EC2 was what I needed to be able to use S3 efficiently.


Corey: And one thing sort of leads to another. And, I think, as anyone tends to learn sooner or later, they, kind of, wind up staying wherever they wind up initially building something out barring a tremendous strategic reason to change providers. So, one thing that I found interesting that I saw a while back and [00:27:05 I'll link to it in the show notes] was Patrick McKenzie wound up doing an entire analysis of Tarsnap and writing—an essay doesn't really encapsulate the entirety of what he wound up writing—it was more or less a day-long tear down of your entire market positioning and effectively giving a laundry list of things he would change if he were doing the marketing piece for Tarsnap. What led to, first, him doing that? And secondly, what was your response when you wound up going through all of the copious detail that he wound up putting in there?


Colin: I can't remember the exact history leading up to that, although, I mean, we had exchanged comments about Tarsnap on Hacker News for a couple years leading up to that. He did ask me, by the way, was I okay with him doing this, and I was very enthusiastic and I still am very enthusiastic. That blog post actually brought Tarsnap more customers than anything anybody has ever written by, probably, a factor of 10.


Corey: Just wait until this podcast goes out and we'll see if we can beat it.


Colin: Well, that would be fantastic. [laughs] But as far as my opinions on what he wrote about Tarsnap, I think his view of Tarsnap is somewhat different from mine. He, and also Thomas Ptacek, who shows very similar opinions to Patrick about Tarsnap, have said that the worst thing for a small business to be is a utility. This idea of pricing Tarsnap the same way that you pay your power bill is just terrible. As far as they’re concerned. My view is exactly the opposite. I think backups should be a utility. And if people can pay their Tarsnap bill the same way that they pay their AWS bill, that is not bad in my opinion.


Corey: I would say that there's definitely an argument that could be made in either direction. The joy of looking at things from a utility perspective is that, okay, great, you wind up paying for things that turn on, turn off. And we've seen companies move away from this. I mean, remember back when Dropbox instead of being a bloated monstrosity that failed to work in most respects and beat your CPU to death whenever something touched a disk when it used to just be a folder that would sync between various computers and have the same contents in it at all times, like magic, that felt like a utility. Now, of course, it's a platform and it certainly worked for them. They've gone public and done super well. But they clearly have departed from their routes of being, do one thing, do it well in a utility fashion, so maybe that means that Tarsnap is not fated to become a publicly-traded company worth billions of dollars.


Colin: That is quite possible and honestly, I don't really mind if Tarsnap fails to become a publicly-traded company. Being a publicly-traded company is an awful lot of work, and I don't think I really want to do that.


Corey: No, no, there's certainly a list of things I want to deal with versus don't want to deal with, and paperwork is very clearly in the second category. That's why the company is never just me. It's always good to have people who are better at things that I suck at. So, something else you've written recently that I wanted to talk about was imds-filterd. That's Indigo, Mike, Delta, Sierra, dash filterd. And one thing that I love about imds is that it the first sentence in the readme tells you how to pronounce it which is a rarity around anything that touches AWS. Usually, it leads to warfare, character assassination, actual assassination, and I still stand by my AMI pronunciation, but what is imds-filterd?


Colin: So, imds-filterd is a filtering daemon for the instance metadata service. Amazon refers to the instance metadata service as IMDS. I'm not quite sure why metadata gets two letters instead of one, but maybe they think meta and data are different words, I'm not sure. In any case, they call it IMDS, so I call it IMDS. And imds-filterd is a daemon which restricts access to whichever parts of the instance metadata service you would like to restrict access to. And it does this based on rules that you provide with user IDs, and also group IDs if you want. So, this means that you could say, this web proxy should not be accessing IAM credentials. We do not want people to use this web proxy to get the credentials to access S3 and steal all of the information on 100 million credit cardholders. Or you could tell it, user nobody should not be accessing things. So, that privilege separated SSHD that you've got running, the preauth process, if there's a vulnerability in there, somebody should not be able to exploit a preauth vulnerability in order to steal those same IAM credentials. 


In general, I would say you probably want to let root access everything, because well, we’ll just root it and turn off the filtering daemon if it wants to anyway, but it's essentially a way of fixing the fact that, in the early days of the of IAM, they decided the right way to expose credentials was via the instance metadata service, which is accessible via HTTP from any process on the system. Honestly, I think that was the worst security mistake Amazon has ever made in AWS, but they haven't fixed it so I figured, well, I need to step in and I need to fix it.


Corey: And step in and fix it you did. They wound up releasing the v2 endpoint, but that's going to take, as I believe you've mentioned, ages for that is globally supported to the point where the v1 endpoint can be turned off. That's going to be a painful thing for a lot of shops.


Colin: Getting to the point that people can turn off Version one access is going to be painful because you need to have code that supports v2 before you can block Version one. Also, v2 doesn't solve the problem completely. It solves the problem of, I have misconfigured proxy. But it doesn't solve the problem of somebody managed to break into my server but within a sandbox. They're running as user nobody, or they found a bug in Apache, so they're able to [00:33:47 uncode] as the www user. Those users should not have access to IAM credentials unless there's some credential you need to have, but in general, they shouldn't have access to those credentials. And even with Version two of the instance metadata service, right now they do have access because they can make the necessary requests.


Corey: Excellent. And I will throw a [00:34:11 link to that in the show notes] as well. Last question before I let you go. You wind up doing an awful lot of work for the larger community, in order to make FreeBSD on EC2 run. If people want to support you, how can they do that?


Colin: So, a couple years ago, I set up a Patreon. The original idea, the way I set it up was just, this will be a way that people can cover things like my travel expenses because there have been times I've considered going to conferences and said, “You know, it might be useful for me to go somewhere like Amazon re:Invent, but I don't really want to pay for that out of my own pocket.” 


As it turns out, now I'm a Amazon Community Hero. So, Amazon pays for me to go to re:Invent. But there have been other events I've considered going to and decided not to because I didn't want to pay for it myself. And at this point also it would be nice if the community could pay for some of the time I spent working on this because I do have a day job and the more time I spend working on getting FreeBSD working on EC2 and fixing issues as they arise, the less time I get to spend on Tarsnap.


Corey: That's absolutely something that is worth supporting. I think that we take people doing what amounts to volunteer work in the open-source space far too much for granted. So, absolutely thrilled to [00:35:30 want to throw in a link into that].


Colin: Great.


Corey: Colin, thank you so much for taking the time to speak with me. If people want to hear more about what you have to say, where can they find you?


Colin: They can follow me on Twitter, @cperciva, or follow my blog daemonology.net/blog.


Corey: Excellent, and we will absolutely [00:35:50 toss links to that in the notes] as well. Thanks once again for taking the time to speak with me, I appreciate it.


Colin: Great to talk to you.


Corey: Colin Percival, founder of Tarsnap and, effectively, one-man force of nature in the FreeBSD ecosystem on AWS. I'm Cloud Economist Corey Quinn, and this is Screaming in the Cloud. If you've enjoyed this podcast, please leave a five-star review and Apple Podcasts. If you've hated this podcast, please leave a five-star review in Apple Podcasts, and a comment explaining why FreeBSD is your favorite distribution of Linux.


Announcer: This has been this week’s episode of Screaming in the Cloud. You can also find more Corey at ScreamingintheCloud.com, or wherever fine snark is sold.


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