Hey @samandmoore, thanks for the PR! I'm investigating how this fits into our CI as well. I think it's going to take some work on our part here.

Currently we're building the final binaries natively, on a Linux amd64 agent and a macOS amd64 agent. So I think we'll have to spin up a macOS arm64 build agent.

Ah gotcha. That's interesting. Ideally you'd be able to use golang cross compilation. Do you know what is preventing that? Is it the linking to the webp library?

Yup, exactly. Since it's a native dependency we can't use cross-compilation (without setting up an entire cross toolchain, anyway).

Update, I'm able to cross-compile Linux amd64 -> Linux arm64, though I've only validated that the produced binary does not execute on an Intel CPU 😄 :

# Install cross compilation tools
sudo apt install -y crossbuild-essential-arm64

# Add arm64 based libewebp-dev package
sudo dpkg --add-architecture arm64
sudo apt update
sudo apt install libwebp-dev:arm64

Then we can run something like this to cross compile with CGO:

CC=aarch64-linux-gnu-gcc CGO_ENABLED=1 GOOS=linux GOARCH=arm64 go build -o pixlet tidbyt.dev/pixlet

./pixlet 
zsh: exec format error: ./pixlet

• CC=aarch64-linux-gnu-gcc tells system what gcc compiler to use
• CGO_ENABLED=1 says even though we're cross-compiling, don't disable CGO since go does that normally
• The ARCH and OS are what you would expect

I think we can follow a similar pattern for MacOS and I'm validating that now

Update, I found an arm64 based linux machine to test on and confirmed it can render the hello_world.star!

Good news! I had a chance to look at this again after the holidays and was able to get this to cross compile for M1 as well. I downloaded libwebp-1.2.2-rc1-mac-arm64.tar.gz from here since it was the only version with MacOS ARM support: https://storage.googleapis.com/downloads.webmproject.org/releases/webp/index.html

Then I was able to reference it to build against:

mspicer@americano:~/code/src/tidbyt.dev/pixlet|main ⇒  CGO_CFLAGS="-I/Users/mspicer/Downloads/libwebp-1.2.2-rc1-mac-arm64/include" CGO_LDFLAGS="-L/Users/mspicer/Downloads/libwebp-1.2.2-rc1-mac-arm64/lib" CGO_ENABLED=1 GOOS=darwin GOARCH=arm64 go build -o pixlet tidbyt.dev/pixlet

Again, was only able to confirm it is not able to run on my machine since I don't currently have an M1 to test against:

mspicer@americano:~/code/src/tidbyt.dev/pixlet|main ⇒  ./pixlet
zsh: bad CPU type in executable: ./pixlet

mspicer@americano:~/code/src/tidbyt.dev/pixlet|main ⇒  file pixlet
pixlet: Mach-O 64-bit executable arm64

Alright! I'm ready to land this. I might still need to make some tweaks here. I'm working on getting everything into GitHub actions so that it's all open source in #104

Awesome! Excited to see this coming together!