next/image should support running behind a proxy

[kungozan]

Describe the feature you'd like to request

With the recent introduction of HTTP agent config through the very beneficial keepAlive (https://nextjs.org/docs/api-reference/next.config.js/disabling-http-keep-alive) being enabled by default Next.js is starting to become opinionated about how fetch agents should work as a default.

With this in mind I think it would also be a good time to introduce proxy configuration options to allow next/image (and other future framework layer HTTP requests) to be ran from behind a proxy.

The primary use-case is for applications forced to run behind an egress proxy to validate outgoing requests.

Issues/discussions describing the same problem:

• Option to configure next/image to fetch with proxy https_proxy #20837
• Using next/image behind a proxy #18376
• Option to configure next/image to fetch with proxy https_proxy #21874

Describe the solution you'd like

Solution 1 (Preferred)

Use the widely accepted HTTP_PROXY and HTTPS_PROXY variables when configuring the fetch agent.

Solution 2

An extension of the existing httpAgentOptions to include a proxy configuration, e.g in next.config.js

module.exports = {
  httpAgentOptions: {
    keepAlive: false,
    proxy: {
        protocol: 'https',
        host: 'https://my-proxy-address.com',
        port: 443
  },
}

Describe alternatives you've considered

An alternative solution is to override the HTTP agent globally like described here but with this solution it will also overwrite the keep alive that the Next.js framework introduces with great benefit.
Without access to the framework I don't see how we can merge agent configs on a per-option basis in a good way, hence the global overwriting, resulting in overriding beneficial behaviours.

[jernkuan]

Would this work?

#47039 (comment)