Registry proxy support

[abtzz]

Problem

The config.json configuration in the cargo index needs to be moved out, because in some scenarios where a proxy is required to access crates.io, the config.json file in the index obtained from the proxy needs to manually modify the dl api configuration in config.json.

Proposed Solution

It is recommended to move config.json out of the index and place it in the ~/.cargo/config.toml file, or use environment variables to configure the config.json's dl api

Notes

No response

[epage]

I've tried to edit the title to summarize the problem, rather than the solution. If I missed some nuance, feel free to refine it.

There are a couple of ways to do proxying today, depending on your need.

• http proxy
• source replacement

Is there something about your situation that makes one of these not work for you? Better understanding of that seems key to finding a path forward.

[abtzz]

Crates mirrors usually only proxy the index, like the tsinghua mirror: https://mirrors.tuna.tsinghua.edu.cn/help/crates.io-index/ , in this file https://mirrors.tuna.tsinghua.edu.cn/crates.io-index/config.json

{
  "dl": "https://static.crates.io/crates",
  "api": "https://crates.io"
}

The download address is still https://static.crates.io/crates,
When I am in an intranet environment, I cannot directly access the external network, and there is no http proxy, only nexus proxy.
The configured nexus proxy format is http://xxx.yyy.zzz/raw-crates-index-proxy Not in [protocol://]host[:port] format.
Configure ~/.cargo/config.toml as follows:

[source.crates-io]
replace-with = 'tsinghua-nexus'
[source.tsinghua-nexus]
registry = "sparse+http://xxx.yyy.zzz/raw-crates-index-proxy"

Executing cargo add xxx; cargo update; is OK
However, when executing cargo build, an error message appears when downloading dependent crates, indicating that the network is down and the download failed.

I had to add another nexus proxy http://xxx.yyy.zzz/raw-crates-download-proxy to proxy https://static.crates.io/crates, and Manually modify the dl in the ~/.cargo/index/xxx.yyy.zzz-hash/config.json file to http://xxx.yyy.zzz/raw-crates-download-proxy as follows:

{
  "dl": "http://xxx.yyy.zzz/raw-crates-download-proxy",
  "api": "https://crates.io"
}

When I run cargo update, the file will be overwritten and restored. I have to modify dl again and again.

ps: I actually use

[source.crates-io]
replace-with = 'aliyun'
[source.aliyun]
registry = "sparse+https://mirrors.aliyun.com/crates.io-index/"

Because when using the tsinghua mirror, I encountered a permission problem when downloading crates, but I did not encounter a permission problem when downloading crates using the aliyun mirror. No matter which mirror I use, I need to manually modify the dl configuration in the ~/.cargo/index/xxx.yyy.zzz-hash/config.json file after executing the cargo update command.

So I hope to move the configuration in config.json to the ~/.cargo/config.toml file, or configure it through environment variables.
Or like the pypi mirror, only need to proxy one address https://mirrors.tuna.tsinghua.edu.cn/pypi/web/simple/, not two index and download addresses