Initial addition of airplane mode #4686

[Ophirr33]

#4686
Hi all, sorry for the delay in getting this implemented. @alexcrichton thanks again for the amazing write up. I have a lot more time now to go back on forth on this, so I wanted to get the first version of airplane mode up for review. I've implemented everything except for the subcommand for populating the offline cache, which I've wanted to discuss some. There's already been some work in this space:

• https://github.com/est31/cargo-local-serve/blob/master/src/bin/download-all-crates.rs
• https://github.com/C4K3/crates-ectype
• https://github.com/Xion/cargo-download

Additionally, one can already download the crates they want by setting up a cargo project with their desired dependencies, and running something like cargo update && cargo build.

We could take the approach of trying to make all of crates accessible offline via some clever caching (@est31 mentioned it's possible to reduce the size of crates to only 3GB), or try to make a better user interface for choosing crates to download. Maybe something like cargo download --popular 100 to download the 100 most popular crates, or cargo download $crate to download the dependencies needed to build a certain crate?

Also, Happy Holidays 🎅🎉!

[rust-highfive]

Thanks for the pull request, and welcome! The Rust team is excited to review your changes, and you should hear from @matklad (or someone else) soon.

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[matklad]

r? @alexcrichton

Not that we already have a PR in flight: #4770

[Ophirr33]

Ah, totally missed that. We can close this one then if more review work has already gone into #4770

[alexcrichton]

Thanks so much for the PR @Ophirr33! Sorry for the switcharoo though :(

At this point I think all of the ideas here are incorporated into #4770 as well except the suggestion of using -Z offline on an otherwise spurious network failure. For now though I'd prefer to hold off on recommending unstable flags until we get some testing of it but I think doing that is a great idea when stabilizing!

I'm gonna close this for now as I think #4770 is pretty close, but of course thanks again for this!