Unable to start dev server with domain configured by PAC (proxy auto-config)

[levrik]

I'm using a PAC (proxy auto-config) file to redirect all domains ending with .local to a local development proxy without messing around with my hosts file.
This seems to don't play well when using the HOST environment variable in cra.

Settings DANGEROUSLY_DISABLE_HOST_CHECK to true has no effect.

Environment

1. node -v: v8.9.0
2. npm -v: 4.0.5
3. yarn --version (if you use Yarn): 1.3.2
4. npm ls react-scripts (if you haven’t ejected): 1.0.17

Then, specify:

1. Operating system: Windows 10

Steps to Reproduce

1. Configure a URL to an PAC file with the following content:

function FindProxyForURL (url, host) {
  if (dnsDomainIs(host, '.local')) {
    return 'PROXY 127.0.0.1:2000';
  }

  return 'DIRECT';
}

2. Setup an reverse proxy (nginx, whatever) to listen on port 2000 with a .local domain configured with the cra dev server as target.
3. Configure HOST to your .local domain.
4. Try to start cra. It gets stuck for some time before showing the above error.

[Timer]

To work around this, add HOST=localhost to your .env file.

[gaearon]

Is there anything we can do to improve this?

[levrik]

@Timer Ah, awesome. HOST=localhost together with DANGEROUSLY_DISABLE_HOST_CHECK=true is a good workaround.

@gaearon I think cra would need to be able to resolve domain names via PAC.
Maybe this could help? https://github.com/TooTallNate/node-pac-resolver
Would still need to get the PAC file out of the system settings.

If this is something that you would like to have supported by cra I could look into it. I think the resolving part is easy with module mentioned above. Just need to find out how to access the system setting on other platforms. On Windows it's possible via registry and Windows API. Not sure if cra should ship native Node addons tho.

Mentioning the workaround in the docs would be a first good step I think.

[Timer]

Our docs mention HOST is respected.

This message would've prevented this issue: #3730, so we should probably merge it. 😄

[levrik]

@Timer no. HOST was set on purpose because I set the proxy option in the package.json and cra complained about the invalid host header.

[stale]

This issue has been automatically marked as stale because it has not had any recent activity. It will be closed in 7 days if no further activity occurs.