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So first, put your hand in the air if you use Homebrew. Good! Put your hand in the air if you have ever contributed to Homebrew, made an issue, or a pull request or commit. Can we get a clap? Thank you! Put your hand in the air if you love Homebrew. Now put your hand in the air if you hate Homebrew.
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So today I'm going to talk about using modern Ruby in Homebrew to build a better, faster Homebrew. First, some background.
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This is not the right background. Put your hand in the air if you hate Windows XP. Good, it is too old. This is almost right, but this Mac version is also too old, and Homebrew does not support it. This also makes me sad.
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Ah, this is better! We have the right background and we can continue the talk now. Homebrew supports this.
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I am Mike McQuaid. I have worked on Homebrew for 15 years and I am the project lead. I'm the CTO of a startup called Work Brew, which I will talk a little more about later. We're doing stuff to make Homebrew better at work.
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I was at GitHub for 10 years and left as a principal engineer last year. After the talk, I have Homebrew and Work Brew stickers, and I found my sticker coverbed again. I have a bunch of GitHub stickers that you can have as well.
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So today I'm going to talk about three things: first, Homebrew and Ruby and our relationship together; next, Homebrew's Ruby tooling that we use and how that's possibly changed in the last four or five years; and finally, what we're doing to build a better Homebrew.
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First, Homebrew and Ruby. Put your hand in the air if you knew that Homebrew was already using Ruby. Okay, some people, not everyone.
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So this text is very small, so you probably can't read it right now. But this is the original first commit of Homebrew, which was 15 years ago next week exactly, which is kind of funny. It was by a guy called Max Howell, up here on May 2009, and the first commit was to this readme file where he talked about how Homebrew was going to work.
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The important bit for us is that Homebrew uses Ruby. From the beginning, Homebrew has relied on Ruby, and it always utilized the Ruby that was provided by macOS. So, Homebrew and Ruby have been very closely aligned from the start. In fact, Homebrew in the very early days looked a lot more obvious that it was using Ruby than it does today.
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To install Homebrew back then, there wasn't a brew command yet, nor a nice website with an installer. You just ran a Ruby command after checking out Homebrew on your disk. Now, it's a curl to bash. I think Homebrew might have been one of the first projects to adopt this. Put your hand in the air if you hate curl to bash. Yes, some people. Put your hand in the air if you love curl to bash.
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Most people don't care, it seems. Installing Wget is a nice example of a simple Homebrew package. It used to look a bit like this: you would just run Ruby and pass the actual formula file directly to run that formula script with Ruby.
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Who knows what a formula is already? A few people, not everyone. Nowadays, you just type 'brew install Ruby', making it easier to forget that you're using Ruby with Homebrew at all.
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Now, I'm going to talk a little bit more about the formula. This is the DSL (domain-specific language) that we use for writing packages in Homebrew. In my opinion, this is one of the biggest reasons that Homebrew has become so popular compared to maybe APT or MacPorts or Debian.
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It's very easy to write a Homebrew package, and one of the big reasons for this ease is Ruby. This is a slightly simplified version, so we can fit it all on one slide. This is a minimal example of what a formula can look like; it's valid as is.
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However, if you go and look at the actual formula, you'll see there are a few more details for boring reasons I won't get into right now. In my opinion, this is extremely readable without being overly verbose.
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I still think that Ruby is the best language for writing beautiful code like this. For this formula, we have 'Wget' which is the name of the class, the package, and the file on disk. This is a type of formula. We've got a description here, 'Internet file retriever'. We have the homepage where we say, 'This is where to go if you want to learn more about Wget'.
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We have the URL from which it's going to be downloaded, and in this case, we're simplifying it; you would actually download it directly from Homebrew. We provide binary packages for you; I'll talk more about that later. Homebrew will download this on our CI systems; we've got a checksum to ensure that this is what we think it is, the license, and then some commands we run.
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Again, if you've written a bit of Ruby, the system command will already be familiar for you. We're just passing this through; the prefix is the special place where we install the software, and then we run 'make install'. So even from this 'def install', it's very easy to see what commands are needed to install Wget under Homebrew.
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As a result, I've seen other people who don't use Homebrew trying to figure out how to build a tool go look at the Homebrew formula because it's often the easiest thing to read if you don't know anything about the package manager itself.
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Here we've got an example of a little test where we're saying we want Wget to dev now because we don't care what the output is. We just want to see if Google.com is up, and hopefully, if it's not, then it's just Homebrew's Wget that's broken and not Google.
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Although maybe this should be ChatGPT nowadays instead. Raise your hands if you know what a Cask is. This is even less widely known than a formula. Yeah, fewer people.
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A Cask in Homebrew used to be part of a separate project called Homebrew Cask, but that was merged back into Homebrew, and now we have them all in the same place. A Cask is generally related to an upstream project where the developers create the packages, binaries, or installer files and we download from them.
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So it works a little differently; we're not having to create build instructions, but we're more concerned with the packages we get and where to put them and how to uninstall them.
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I'm not going to go through this in as much detail because I don't think it's quite as interesting, but we have different things for the different architectures. This is for one password; we've got different checksums for the different architectures.
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We're using a different download depending on the system, whether on Apple Silicon or on Intel x86. We've got the URL for downloading, the name and description similar to a formula, and we're stating that it auto-updates.
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This means that this version might not always be correct because one password can update itself after you've installed it. We also indicate the Mac OS version it depends on and the app file it installs.
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This is a bit minimal; the actual thing is slightly larger, but not by much. Another thing worth noting is that Homebrew now fully runs on Linux. Most packages can be installed and work nicely on Linux as well, but Casks are, for now, only available on Mac OS.
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We also write Casks in Ruby. This is a nice modern example of what we're doing nowadays using Sorbet, a Ruby type checker that has come out of Stripe. We have this command; if you run 'brew docs', you can specify the arguments.
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This command doesn't actually have any arguments but does have a description for help output and all this type of stuff. We also want to run a browser to go to Homebrew's website; even if you don't know much Ruby, it's quite nice and readable.
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I mentioned Homebrew was initially released in 2009, back when it was macOS 10 Leopard, and it came with Ruby on the system, which was pretty cool at the time. In 2009, that was Ruby 1.8.7, which was released in 2008, so it wasn't too old and was just right.
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It meant that Homebrew didn't have to figure out how to install Ruby to run on a Mac system before you could start using it; Apple did that all for us. Unfortunately, as we were relying on the Apple version, by 2016, we were still running Ruby 1.8.7.
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In 2016, my face would look like this every time I had to write with Ruby 1.8. I'd find some lovely new feature released ages ago in Ruby 1.9 or something and every single time... Raise your hand if you still have to run Ruby 1.8 anywhere in 2024? Oh, just a few people. Sorry for you.
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By 2017, things improved a bit. I still have my eyebrow raised because I'm not quite as happy as I would like to be. Ruby 2.4 had already been released, but Apple released Ruby 2.3 with macOS. So we could rely on this version, and it was not too old.
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By 2019, however, we were falling into the same pattern again and having to rely on older versions. At the last RubyKaigi, I talked about running Ruby 2.3; does anyone still run 2.3 in production? Fewer than 1.8, interesting! By 2019, macOS finally came with a newer version.
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But still, by 2023, we were stuck on Ruby 2.6.1 on my lovely Apple Silicon laptop running the latest version of macOS today. This situation makes me very sad, but we have some people at Apple we talk to, and they reminded us that the Ruby on the system is deprecated and we shouldn't be using this anymore.
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We said, 'Yes, but that's not us, right?', and the rules don't apply; we are Homebrew people. But they advised us to fix the problem ourselves. So, with tears in my eyes, I had to say goodbye to macOS Ruby entirely for now.
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We asked Apple for a newer version, but we didn't get what we wanted. However, we managed to get a slightly newer Ruby ourselves and moved onto Ruby 3.1.
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During this conference, I heard discussions from people like Jay Hathorne and Aaron Patterson, who showcased a new profiler for Ruby. It looked really shiny, and I wanted to set it up with Homebrew, but I was disappointed to find it needed Ruby 3.2.
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I thought, 'Can I get Homebrew upgraded to Ruby 3.3 during RubyKaigi?'. I was happy to get the pull request merged 48 minutes ago.
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Now, this didn't get updated in the last 48 minutes. We have this thing called Portable Ruby in Homebrew. This originated back when we were on Ruby 2.3 or 2.6 because we had to support older versions of macOS.
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We wanted to use the newer Ruby, so originally Portable Ruby was created to install a Ruby version compatible with all supported macOS versions. Now, with Ruby 3.1, we are moving entirely to our own Portable Ruby.
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So now, if you're on Linux, you can supply a Ruby version from the system, but if you're on macOS, you're always running Portable Ruby. This is great because it gives us more control over the Ruby versions in Homebrew.
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So, I've talked a bit about Homebrew's relationship with Ruby and how we moved around the versions. Now, I'm going to discuss Ruby tools used in Homebrew. RuboCop deserves the first mention because we use it widely for many things in quite cool ways.
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Initially, we used RuboCop for Homebrew's internals to enforce some rules and ensure code consistency, which helped us review pull requests. Homebrew has had about a thousand contributors over 15 years.
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With around 30 people now, we have a lot of work to keep up with. We try to automate as much as possible, so RuboCop has become an essential tool for that.
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Over time, we built it into Homebrew. If you type 'brew style wget', it checks the contents of the file on disk against our style guidelines. We also have custom RuboCop checks that enforce ordering in formula files and a lot of them have autocorrection support.
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If you're using an editor like VS Code with auto-correct enabled, it will modify things according to Homebrew's style guidelines. I encourage other open-source projects to consider using RuboCop and auto-correct to improve the quality of contributions.
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'brew style' checks Homebrew's code and we run it in our CI to ensure we meet our standards. It reduces the need for internal discussions about styling rules in pull requests, shifting the focus to what rules should be defined.
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Since 2019, we've started using Sorbet, the type checker for Ruby from Stripe. We initially brought it in for specific files, but we're moving to use it more extensively.
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We are increasingly removing runtime checks in favor of Sorbet checks and have enabled it by default for developers. Now, we have the 'brew type check' command, which checks things via Sorbet.
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We expect to make much of Homebrew type strict because we found it helps catch many errors, providing better documentation for our Ruby DSLs.
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Regarding our test suite, who here has a test suite with 100% coverage? No one? One person? Okay! I'm coming to check to ensure it's legit!
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Ours has around 70-75% coverage, which is decent, catching many edge cases since Homebrew has been around for a long time. It doesn't catch everything, but we're finding Sorbet really helps catch issues RuboCop may have missed.
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Speaking of tests, we use RSpec for that. There was a survey outside showing many people use RSpec compared to MiniTest.
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If you run 'brew tests', that's what we do there, and thanks to the parallel tests gem, we run in 10 processes, which speeds things up. It takes about six minutes on my two to three-year-old Mac.
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We've achieved a good balance with the Homebrew testing system, enabling us to verify that things work without having a test suite that takes hours.
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In this final part of the talk, I'm going to discuss what we're doing in Homebrew to improve things better.
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In particular, I will address what we aim to enhance in the coming year, so if I'm at RubyKaigi next year, feel free to tap me on the shoulder and ask why those things didn't improve as I suggested.
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The first area in Homebrew is improving performance. Who finds Homebrew too slow? Not many, but Google disagrees.
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So, we talked about why it's written in Ruby. I can't help with why it might not be installing correctly. Let's discuss the slowness issues a little bit.
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I decided to make a last-minute addition to my slides, as I tend to procrastinate. Initially, I included a line suggesting people love Homebrew; however, with the latest updates, we need to improve the speed.
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Recently, I made Brew list much faster, and compare that to PIP list; Brew list is now 1.28 times faster!
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A lot of discussions about performance optimization occurred during the conference. How do we make Homebrew much faster?
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Is it porting Ruby to Rust? People are using Rust for improving the performance of their Ruby applications, or porting to C? I don't know. I've heard the idea of using Bash was raised.
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Let me show you this new development. When you run Brew commands, the initial execution runs a bit of Bash to clean up the environment before executing Ruby code, which includes a lot of requires. It runs slowly for simple commands.
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We aim to lessen the dependencies of each command and shift calls to Bash for commands that can be handled the same way.
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You may have seen Hyperfine discussed in other talks; it's quite useful for benchmarking. It allows comparisons and benchmarks on Ruby versus Bash, and it shows how long it takes to execute each command and variations.
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We've noted that for 'brew prefix', running in Ruby takes around 400 milliseconds, compared to 26 milliseconds in Bash.
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Therefore, while Ruby is slow, Bash can outperform it in many command situations due to the overhead Ruby entails.
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Finally, we are incorporating better security into Homebrew. We've had several security audits over the last few years.
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We've published one of those audits on Homebrew's blog and are working on another that we hope to publish once we fix a few more outstanding issues.
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Additionally, GitHub Actions introduced attestation, which if verified will allow you to know whether the binary package provided came from GitHub Actions and CI systems. It is not enabled yet but we hope to see it available soon.
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In my work on Homebrew, I found the security aspect quite challenging, as we cannot always open-source all of it as big companies might desire.
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Last year, I started a company called Work Brew focused on making Homebrew work better with tools like MDMs (Mobile Device Management) including Jamf or SimpleMDM. We're also looking to develop engineering specifically innovation features.
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We have our installer, which works offline, provides portable Ruby, and sets up both Work Brew and Homebrew simultaneously.
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We have a nice interface allowing you to see every device in your fleet of MacBooks, checking what is outdated and what is ready for upgrades.
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You can easily upgrade a formula or deploy it across many devices. If you're interested in Work Brew, feel free to talk to me, email me, or visit our website to fill out the contact form.
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There's a demo video available on our website explaining everything we are doing. Throughout this talk, I shared some insights about Homebrew and Ruby, their long-standing relationship, and how we're keeping up with newer versions.
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We also discussed the Ruby tools like Sorbet, RuboCop, and RSpec that we rely on heavily at Homebrew. And finally, how we aim to build a better Homebrew in terms of performance and security.
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Because this is RubyKaigi, with all of you brilliant Rubyists, I invite you to help us on our journey to improve Homebrew. If you need assistance or if our contribution documentation confuses you, please reach out, and I'll be happy to help you get started.
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Thank you very much for your attention! Feel free to contact me or ask any questions via Mastodon, Twitter, or email.
