Homebrew on Apple Silicon
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Today, my new 13-inch MacBook Pro arrived! I was super excited to get it out of the box and set it up. This thing is fast! I am already very impressed. When I started setting up my development environment, things started to get a little frustrating. Have no fear, it’s solvable!
The biggest issue for me was Homebrew. According to this issue “There won’t be any support for native ARM Homebrew installations for months to come.” No big deal though. Homebrew can work just fine with Rosetta 2 and some things work natively.
Using Rosetta 2
Rosetta 2 is Apple’s translation layer. This lets you run Intel things with a little overhead. In Terminal, you can run any process with Rosetta by prefixing it with arch -x86_64.
To get Homebrew working, let’s install it using Rosetta:
$ arch -x86_64 /bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install.sh)"
This command is the standard installer from brew.sh with the Rosetta prefix. This will setup Homebrew in /usr/local. Now whenever you want to interact with it, you can run arch -x86_64 brew …. Easy enough!
If you want to wait for official support for Apple Silicon, feel free to stop reading here.
Multiple Homebrews
Homebrew does sorta work on Apple Silicon. See this issue for the current status. OpenJDK and Go don’t work as of this writing and that blocks a lot of things. I was able to get Postgres, Redis, ImageMagick, rbenv, etc. all working natively though! To do this, you’ll need a second Homebrew.
Homebrew for Apple Silicon is expected to be installed in /opt/homebrew instead of the /usr/local you’re expecting. Let’s get that set up:
$ sudo mkdir -p /opt/homebrew
$ sudo chown -R $(whoami):staff /opt/homebrew
$ cd /opt
$ curl -L https://github.com/Homebrew/brew/tarball/master | tar xz --strip 1 -C homebrew
This creates a new directory, setups the right permissions, and downloads Homebrew.
Be sure to add /opt/homebrew/bin to your $PATH!
Whichever brew is in your path first will run when you use brew. If it’s the /usr/local one, you’ll need to add the arch -x86_64 prefix every time. Your best bet for using both is to alias one of them.
I made sure /opt/homebrew/bin was in my path before /usr/local/bin. Then I aliased the Intel brew to ibrew so it’s easier to select. Here’s what I added to my ZSH configuration:
export PATH="/opt/homebrew/bin:/usr/local/bin:$PATH"
alias ibrew='arch -x86_64 /usr/local/bin/brew'
Now you can easily run brew to get the native one or ibrew to get the Rosetta one. You could of course do this in the other order in your $PATH if you prefer and something like abrew (for Apple Silicon Homebrew) or whatever else.
If you install things in both Homebrews, the one that is first in your path will be used.
Disclaimer: This is as of 2020-11-17. Things are surely going to change. Follow along in this issue for the latest from the Homebrew team.
Update 2020-11-18: I realized both at the same time wasn’t working as I described. Updated the multi section.
Update 2020-12-31: If you are having trouble installing Ruby, check out this post.