Modify `rustup-init.sh` to support retrying the download of `rustup-init`

[yilmazdurmaz]

Describe the problem you are trying to solve

I am a newbie trying to install rustup. it is having difficulties on downloading required packages from static.rust-lang.org because the connection constantly drops randomly, it tries to reconnect 3 times all starting from zero (does the host not have resume capability!?, I dont know) then just fails the install progress. each reconnection fails at different percentages, one was at 15% while another at 95%.

Describe the solution you'd like

Instead of halting the progress, inform them and prompt users if they want to try for more.

Also, check beforehand that if the host has resume capability and again inform users about that. currently I am not sure who to blame for starting over the download progress.

Notes

as of now, I could not complete the installation and unfortunately lost appetite towards rust for now. I hope problems would be solved till next time.

[kinnison]

I think the situation you described could be improved by making rustup-init.sh pass retry flags when downloading rustup-init. That can, in turn, attempt to retry downloads. In general static.rust-lang.org's CDN is very reliable, but this is something we could do to improve matters.

I'm very sorry that you have lost your appetite to try Rust for now, I hope that you will consider trying again in a few days when hopefully whatever plagued the CDN is fixed.

[abhyuditjain]

If it's up for grabs, I'd like to take it up.

[abhyuditjain]

@rustbot claim

[abhyuditjain]

Can some one give me a general idea on what needs to be done here?

[kinnison]

The work is to alter rustup-init.sh to pass the correct retry flags to curl when using that to download the Rustup binary. I believe wget automatically retries, so it's just curl which will need relevant arguments.

It'll be worth checking when the retry arguments were introduced to curl so that we can do version detection if necessary.

[yilmazdurmaz]

hi @kinnison and @abhyuditjain

besides the retrying part, it may also be best to check if the files I was failing (and I was failing on different files at different percentages) are really resumable sources from static.rust-lang.org. (I hope this is not the case in the year 2021 and beyond)

if it is resumable, then you should also add this info to the downloader to have a cached file to resume. otherwise, retries consume lots of data if someone tries the installation over mobile data. (I was not but I could be)

PS: thanks for your interest in the issue. today I tried again to a successful installation without the hiccups. hope you find a fix for future installs.

[kinnison]

I believe that (a) static.rust-lang.org supports continuation (we use that in rustup itself) and (b) curl's retrying will use continuations.

[garasubo]

@abhyuditjain Is there any progress on it?
If not, I can work on this in this weekend.