Why Go?

[pepicrft]

While checking out the repositories in the organization, it got my attention that the logic for pulling and pushing images was is implemented in Go. I couldn't find anything documented about it, so I thought I'd open an issue and ask.

Feel free to close it if this information is private and don't feel comfortable sharing. I'd completely understand it.

[tomekjarosik]

@pepicrft Primary reasons for this repo being in Go is that this is also a library for Fugaci (integration with Kubernetes). Another one is that it's using go-containerregistry library for Google, which provides higher levels of abstraction. This way this repo only deals with disk usage/bandwith optimization specific to big opaque binary files (like VM images)

[pepicrft]

Thanks a lot @tomekjarosik for the context, that makes sense. I'm not familiar with go-containerregistry, but I'm surprised the optimizations you mention are not built into that package. Is it because the optimizations are very specific to the Virtualization framework?

[tomekjarosik]

@pepicrft Yes, the optimization I'm taking about it's because I don't have any insights into how filesystem for macOS virtualization is serialized. Docker uses its own filesystem layers, has intimate knowledge how to combine them together. Plus docker layers are tiny, ~100x smaller compared to typical macOS VMs. It's not unusual to see few hundred MB for docker image, but it's normal to see 50GB for macOS VM with single Xcode. AFAIK we can't use the same approach, but also we don't have to just upload/download everything every time. Optimization I'm talking about are far from ideal, but better than zip+upload+download+unzip.