Add Rust platform

[scorphus]

• Add basic platform support
• Support code deployment
• Support customized code deployment
• Allow choosing Rust distribution: nightly, beta or stable
• Support binary deployment
• Add tests

[ayr-ton]

@bltavares

[jonnyguio]

Hello @scorphus. How's the current status of this? I think it's looking really nice, and I'd love to see Tsuru offering a default Rust platform.

I believe if we remove the rust-docs, it could greatly reduce the base rust platform image size. Also, I believe it should be more strict with which toolchains are allowed, using the .rust-toolchain file.

I'd like to know if you're still interested in finishing it, or do you want to pass ahead this issue.

[scorphus]

Hey, @jonnyguio! I'm glad this issue caught your attention! I tried to give it some traction by adding the hacktoberfest label two years ago, but nothing much happened.

That's great, I'll be very happy seeing it solved! A lot has changed in Rust since then and I like your suggestions. I've updated the initial commit, mostly to remove the “WIP” part. So please feel free to work on top of it ‒ just please remember to keep it as is.

What do you think if I open a pull request with the existing code and we both work on it ‒ code/review?

[jonnyguio]

Hey, @scorphus. Thanks for the quick reply!

I'm really glad to hear that! I believe that opening the pull request is a great idea, so we can both work on it. You're right, a lot has change since two years ago, and the debut of the 2018 version is very close now. So, I think it's about time to address this issue.

After seeing your code (and also do some myself), I started wondering about the following questions:

• How to offer the Rust Platform. By choosing the toolchain? Choosing the version (Rust 2015, Rust 2018)?
• Which components of Rust it should be installed?
• How the Rust code should be compiled and installed in each deploy?

The last one is more about how to follow the default organization of Tsuru, to be consistent with the other languages (for example, the executable should be in /home/application/current).

What are your opinions? Feel free to answer it here or in the future PR.