Add support for no_proxy / NO_PROXY

[jongolden]

I am currently blocked from using this package due to the lack of support for NO_PROXY.

Here is my scenario:

• I am working behind a corporate proxy and have HTTP_PROXY set as proxy.company-subdomain.com:8080
• I am required to download mongodb from an internal mirror at https://mirror.company-subdomain.com/mongodb-linux[...]
• Internal URLs should not be called through the proxy, so I have NO_PROXY set to .company-subdomain,localhost
• Calling internal URLs through the proxy will always result in a BAD_GATEWAY error

I'd like to see support for NO_PROXY in this package. It looks like it would involve updating MongoBinaryDownload#download such that it resolves the proxy similar to request's getProxyFromUri, which returns null if the URL is included in the NO_PROXY variable.

Let me know if you are willing to support this and I would be happy to open a pull request.

[hasezoey]

for proxy we are currently using https-proxy-agent, which from what i can tell does not support setting any no-proxy settings, so that means we would either need to handle that our-self or switch to a different agent package - or completely switch to how we download things (like for example switching to request directly).
so this effectively means it is put off until at least a minor version.

workaround for now should be to unset the proxy variable you use for MMS, because the only access MMS does is in MongoBinaryDownload.download

Note: i have no experience in messing with proxies, so the workaround may not be fully correct and self-implementation would be too much for this single package

---

Edit:
i am open for suggestions for replacements for https-proxy-agent and something like request (which is deprecated), the requirements are:

• no big dependencies
• API that supports settings proxy and no-proxy
• should work with https and http

[jongolden]

I don't think https-proxy-agent needs to be replaced. It would be simple enough to replace

const proxy =
      process.env['yarn_https-proxy'] ||
      process.env.yarn_proxy ||
      process.env['npm_config_https-proxy'] ||
      process.env.npm_config_proxy ||
      process.env.https_proxy ||
      process.env.http_proxy ||
      process.env.HTTPS_PROXY ||
      process.env.HTTP_PROXY;

with something like

const proxy = getProxyFromUrl(downloadUrl);

Where getProxyFromUrl returns null if NO_PROXY is applicable to downloadUrl, otherwise returns the evaluation of the existing statement.

request's getProxyFromUri is just an example for how this might be implemented. Sorry for any confusion.

[hasezoey]

I don't think https-proxy-agent needs to be replaced. It would be simple enough to replace

i know that this could be done, but like i said it is kinda out-of-scope for this project to handle and should be handle-able by the library actually consuming the proxy