Expo-start in dev-container with MacOS gives the wrong lan link ip

[O1H9]

Summary

Coding with Visual Studio Code and Dev Container, upon expo start, metro sets a link unreachable. my pc has a 192.168.X.X ip, metro sets 172.17.0.3 .

expo start happens into the dev-container.

This works on Ubuntu's Laptop, in the same network, and the same dev-container (almost: current pc needed 'bullseye' version), but doesn't work on MacBook.

node -e 'console.log(os.networkInterfaces())'
{
  lo: [
    {
      address: '127.0.0.1',
      netmask: '255.0.0.0',
      family: 'IPv4',
      internal: true,
      cidr: '127.0.0.1/8',
      ...
    }
  ],
  eth0: [
    {
      address: '172.17.0.3',
      netmask: '255.255.0.0',
      family: 'IPv4',
      internal: false,
      cidr: '172.17.0.3/16',
      ...
    }
  ]
}```


### Environment

expo-env-info 1.0.2 environment info:
System:
OS: Linux 5.10 Debian GNU/Linux 11 (bullseye) 11 (bullseye)
Shell: 5.1.4 - /bin/bash
Binaries:
Node: 14.19.0 - /usr/local/bin/node
Yarn: 1.22.17 - /usr/bin/yarn
npm: 8.6.0 - /usr/local/share/npm-global/bin/npm
npmPackages:
expo: ~44.0.2 => 44.0.6
react: 17.0.1 => 17.0.1
react-dom: 17.0.1 => 17.0.1
react-native: 0.64.3 => 0.64.3
react-native-web: 0.17.1 => 0.17.1
npmGlobalPackages:
eas-cli: 0.50.0
expo-cli: 5.3.1
Expo Workflow: managed

### Please specify your device/emulator/simulator platform, model and version

MacOS Monterey 12.3.1 ––> alpine Dev-Container nodejs 14 bullseye

### Error output

_No response_

### Reproducible demo or steps to reproduce from a blank project

1. In a MacBook, the same version as the one described, create an expo project.  
1. using microsoft dev-container extension in vscode create and open the dev-container   
1. expo-start in terminal  
1. try to connect.

[O1H9]

Note: working with DevContainers in Ubuntu gave me no problems whatsoever as vscode forwarded the right ip and port. With this Macbook i got only localhost working so i am able to open the metro page.

[O1H9]

Also note that i also am using dev-containers to develop a angular app, and it works just just fine with ng-serve, it uses localhost

[O1H9]

Made a stackoverflow's question, linking here for anyone who will have the same problem (but it's still unresolved, please keep this open)

[O1H9]

tried

• without macos firewall
• setting up REACT_NATIVE_PACKAGER_HOSTNAME
• tunnel connecion
  • doesn't work, but it's for another time

I don't know what to look for anymore but i'm looking for some docker nat explanation/solution and some way of docker port mapping

[kbrandwijk]

I use VS Code Remote Containers, and setting REACT_NATIVE_PACKAGER_HOSTNAME to the IP of my host works fine for me. I set it up as part of the docker container definition, but you should be able to run REACT_NATIVE_PACKAGER_HOSTNAME=192.xxx.yyy.zzz expo start or whatever your host IP is. Also make sure that if you use a dev-container, that you have port forwarding set up for 8081, 19000-19002.

[O1H9]

but you should be able to run REACT_NATIVE_PACKAGER_HOSTNAME=192.xxx.yyy.zzz expo start or whatever your host IP is.

thanks, I just tried but doesn't seem to work. I got the same behaviour like exporting REACT_NATIVE_PACKAGER_HOSTNAME before expo start

Also make sure that if you use a dev-container, that you have port forwarding set up for 8081, 19000-19002.

about that, i checked vscode forwarded port and found only 19000 and 19002. I promptly added 8081 as you pointed out but didn't change the result

[O1H9]

also just found out exactly how expo-go fails with java.net.ConnectException: Failed to connect to /192.x.x.x:19000

[byCedric]

Hi @O1H9! You would need additional configuration for WSL2 to allow connections from other devices, other than your computer, into the WSL2 environment.

There are different approaches to this:

• Using WSLHostPatcher
• Using USBIPD

Hope this helps!