Building a react native app in WSL2

rearct-native-app-in-wsl2.md

Building a react native app in WSL2

Install, build and debug a react native app in WSL2 (Windows Subsystem for Linux) and Ubuntu.

• Install tools in Windows
• Install tools in WSL2
• Connect to android hardware device from WSL2
• Connect to android virtual device in Windows
  • Start android virtual device in Windows
  • Start adb server in Windows
  • Enable access to adb server from WSL2
  • Enable access to metro bundler from Windows
• Connect to Windows Subsystem for Android
• Create react native app in WSL2
• Build app in WSL2
• Debug app in Visual Studio Code from WSL2

Install tools in Windows

• Install WSL2 and Ubuntu, see here
• Install Android Studion, see here
• Install Viusal Studio Code, see here

Install tools in WSL2

• Install java-8-openjdk in WSL2 (sudo apt-get install openjdk-8-jre)
• Install Android SDK cmdline tools in WSL2, see here and adjust directory structure, see here
• Install nodejs in WSL2, see here

Set environment variables in .profile or .bash_profile

export ANDROID_HOME=/home/xxx/Android/cmdline-tools/latest
export ANDROID_SDK_ROOT=/home/xxx/Android

PATH=$PATH:$ANDROID_SDK_ROOT/platform-tools
PATH=$PATH:$ANDROID_HOME/bin

export JAVA_HOME=/usr/lib/jvm/java-8-openjdk-amd64

Connect to android hardware device from WSL2

To debug on a hardware device connect to android device via usbip from WSL2 (thanks to @cjshearer):

• Connect USB device to WSL
• Enable USB debugging on the device

Connect to android virtual device in Windows

To debug on a virtual device create a virtual device (e.g. Nexus_5X_API_29) in windows with Android Virtual Device Manager from Android Studio.

Start android virtual device in Windows

Start Android virtual device (e.g. Nexus_5X_API_29) in windows

"C:\Program Files (x86)\Android\android-sdk\emulator\emulator.exe" -avd Nexus_5X_API_29

Start adb server in Windows

adb kill-server
adb -a nodaemon server start

Change firewall rule for adb.exe on first usage in Defender Popup or with Windows Defender Firewall allowing access for the public profile, because the vEthernet (Wsl) adapter belongs to the public profile

Enable access to adb server from WSL2

Set environment variable to access adb server, WSL_HOST is ip of vEthernet (WSL) interface in windows

export WSL_HOST=$(tail -1 /etc/resolv.conf | cut -d' ' -f2)
export ADB_SERVER_SOCKET=tcp:$WSL_HOST:5037

Somtimes adb crashes using the environment variable config. One solution is to use socat (thanks to @tuanna1601).

Unset the environment variable if necessary.

unset ADB_SERVER_SOCKET

Install socat (eg. sudo apt-get install socat). Socat relays the requests from wsl2 to windows using the following command:

socat -d -d TCP-LISTEN:5037,reuseaddr,fork TCP:$(cat /etc/resolv.conf | tail -n1 | cut -d " " -f 2):5037

Enable access to metro bundler from Windows

The metro bundler is running in WSL2, listening on port 8081. Windows 10 version 2004 brings network forwarding from WSL2 to Windows. So the app can connect to the metro bundler from the emulator via Windows localhost.

Sometimes there are problems with the network forwarding. A work around is to use the following script.

WSL_CLIENT is ip of WSL2.

iex "netsh interface portproxy delete v4tov4 listenport=8081 listenaddress=127.0.0.1" | out-null;
$WSL_CLIENT = bash.exe -c "ifconfig eth0 | grep 'inet '";
$WSL_CLIENT -match '\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}';
$WSL_CLIENT = $matches[0];
iex "netsh interface portproxy add v4tov4 listenport=8081 listenaddress=127.0.0.1 connectport=8081 connectaddress=$WSL_CLIENT"

Connect to Windows Subsystem for Android

To debug the app running on Windows Subsystem for Android (WSA).

Install Windows Subsystem for Android.

Start adb server in Windows.

Enable access to adb server from WSL2.

Enable access to metro bundler from Windows Subsystem for Android

The metro bundler is running in WSL2, listening on port 8081.

To enable access from WSA to WSL2, configure adb reverse port forwarding on WSA.

Connect to the WSA via 127.0.0.1:58526 and execute adb reverse.

adb connect 127.0.0.1:58526
adb reverse tcp:8081 tcp:8081 

Create react native app in WSL2

npx react-native init AwesomeProject

Build app in WSL2

Add paraameter in file proguard-rules.pro to ignore okhttp3 warnings

-dontwarn okhttp3.internal.platform.*

Start metro JavaScript bundler and bind to an ipv4 address to enable port forwarding to windows

npx react-native start --host 127.0.0.1

Build app, set device as parameter deviceId from result of adb devices

• deviceId emulator: emulator-5554
• deviceId WSA: 127.0.0.1:58526

npx react-native run-android --variant=debug --deviceId <deviceId>

Debug app in Visual Studio Code from WSL2

Start vs code in WSL2

code .

and install extensions for VS Code

• Remote - WSL
• React Native Tools

VS Code UI runs in windows and the VS Code Server runs in WSL2, see here

Add a launch configuration in file launch.json with specified type and request

"name": "Attach to packager",
"cwd": "${workspaceFolder}",
"type": "reactnative",
"request": "attach"

Build app, attach to packager and start debugging, see here.

I always have to execute the Metro Bundler Forwarding to connect to react-native... anyone knows why? Is there a definitive way to do this?

I also have to execute the Metro Bundler Forwarding on startup before npm start.
I created a simple script executable from WSL to start the forwarding, along with starting the adb server.
I thought I'd share it here:

• some/wsl/folder/start_adb.sh

#!/usr/bin/env sh

winpwd=$(printf "%s" "$PWD" | sed 's/\//\\/g')
powershell.exe Start-Process -Verb runas powershell.exe -ArgumentList "\"-NoExit -ExecutionPolicy Bypass \\\\wsl\$\\Ubuntu$winpwd\\proxy_adb.ps1\""

• some/wsl/folder/proxy_adb.ps1

# Forward metro
iex "netsh interface portproxy delete v4tov4 listenport=8081 listenaddress=127.0.0.1" | out-null;
$WSL_CLIENT = bash.exe -c "ip addr show eth0 | grep -oP '(?<=inet\s)\d+(\.\d+){3}'";
$WSL_CLIENT -match '\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}';
$WSL_CLIENT = $matches[0];
iex "netsh interface portproxy add v4tov4 listenport=8081 listenaddress=127.0.0.1 connectport=8081 connectaddress=$WSL_CLIENT"
# Start adb server
adb kill-server
adb -a nodaemon server start

Simply launch the start_adb script, it will prompt you for admin rights. Remember to add adb to windows path.

New Method for Android

1. Install the sdk manager (without needing android studio).

2. For physical devices: usbipd-win can now be used to expose your android device (or any usb device) directly in WSL2. I've tested and used this to deploy react-native apps to my android device. In addition, this method will work with debugging tools like Flipper, as it doesn't rely on a Windows ADB server.

See the discussion here if you have any issues getting it working for ADB: dorssel/usbipd-win#60

@cjshearer thank you very much, got it work on my box

@cjshearer @bergmannjg i'm trying to connect my Android device from WSL2. Everything is fine with usbipd-win, even my device shows up in "adb devices" command (WSL2). But i get an error when i try "npx react-native run-android"

error Failed to install the app. Make sure you have the Android development environment set up: https://facebook.github.io/react-native/docs/getting-started.html#android-development-environment. Run CLI with --verbose flag for more details.Error: Command failed: ./gradlew app:installDebug -PreactNativeDevServerPort=8081

Also, i've tried with "npx react-native run-android --deviceId=", still i get an error, but it says

error Failed to build the app. Run CLI with --verbose flag for more details. Error: Command failed: ./gradlew build -x lint

How do you guys make it work?
My last last last step is use Ubuntu directly (dual boot alongside Windows).

@bergmannjg By the way, i've also tried connecting android virtual device in Windows from WSL2, and i also get the second error.

@RakaDoank what is the error msg of

./gradlew app:installDebug -PreactNativeDevServerPort=8081

@bergmannjg i get

bash: ./gradlew: No such file or directory

i only found out the error after you asked. So, i tried gradle wrapper first and run the ./gradlew command again, then i get this new error

Project 'app' not found in root project 'myProject'

I'm sorry, this is probably not a WSL issue.

Has anyone have an updated version of the guide? Been stuck on different places.

ERROR ON:

adb kill-server
adb -a nodaemon server start

emulator-5554: already offline
what does this mean?

For those struggling with Expo with the error Couldn't start project on Android: could not connect to TCP port 5554: Connection refused

I'm no expert, but debugging things a little with variables EXPO_DEBUG=1 and ADB_TRACE=adb, I found out that expo start was executing the command adb -s emulator-5554 emu avd name , and somehow this command from the Ubuntu side didn't work (maybe someone here can help fix this), but the adb running on Windows could run that command from Ubuntu with adb.exe.

So, I successfully overrode that with sudo ln -s /mnt/c/Android/Sdk/platform-tools/adb.exe ~/Android/sdk/platform-tools/adb after backing up the original ubuntu adb executable (just fix that path with your windows adb path and your possible custom ubuntu adb path)

I did that only when running the expo start command and all worked smoothly (until now at least)

If anyone can help us to find out why adb on ubuntu side cannot access the emulator, I would appreciate it (even when adb devices runs normally and lists the device)

---

PS: all worked without

• any netsh interface portproxy or
• any adb reverse or
• firewall rule to allow WSL ports (only rule to allow adb program)
• admin rights command execution
• socat alternative

But I used the variables below:

export WSL_HOST=$(tail -1 /etc/resolv.conf | cut -d' ' -f2)
export ADB_SERVER_SOCKET=tcp:$WSL_HOST:5037
export ADB_TRACE=adb
export EXPO_DEBUG=1
export ANDROID_SERIAL=emulator-5554
export REACT_NATIVE_PACKAGER_HOSTNAME=$(ip addr show eth0 | grep -oP '(?<=inet\s)\d+(\.\d+){3}')

and...

• used same version of platform-tools on both windows and ubuntu
• used adb kill-server && adb -a -P 5037 nodaemon server start on Windows side after emulator loaded

versions...

• Windows 11 and Ubuntu 20.04
• expo-cli 5.4.3
• last version of node and npm (v16.15.0 - v8.8.0)
• emulator running avd Pixel_4_API_30 with Google APIs
• usb debug mode enabled on emulator
• adb version 1.0.41 and platform-tools 33.0.1

For those struggling with Expo with the error Couldn't start project on Android: could not connect to TCP port 5554: Connection refused

I'm no expert, but debugging things a little with variables EXPO_DEBUG=1 and ADB_TRACE=adb, I found out that expo start was executing the command adb -s emulator-5554 emu avd name , and somehow this command from the Ubuntu side didn't work (maybe someone here can help fix this), but the adb running on Windows could run that command from Ubuntu with adb.exe.

So, I successfully overrode that with sudo ln -s /mnt/c/Android/Sdk/platform-tools/adb.exe ~/Android/sdk/platform-tools/adb after backing up the original ubuntu adb executable (just fix that path with your windows adb path and your possible custom ubuntu adb path)

I did that only when running the expo start command and all worked smoothly (until now at least)

If anyone can help us to find out why adb on ubuntu side cannot access the emulator, I would appreciate it (even when adb devices runs normally and lists the device)

PS: all worked without

• any netsh interface portproxy or
• any adb reverse or
• firewall rule to allow WSL ports (only rule to allow adb program)
• admin rights command execution
• socat alternative

But I used the variables below:

export WSL_HOST=$(tail -1 /etc/resolv.conf | cut -d' ' -f2)
export ADB_SERVER_SOCKET=tcp:$WSL_HOST:5037
export ADB_TRACE=adb
export EXPO_DEBUG=1
export ANDROID_SERIAL=emulator-5554
export REACT_NATIVE_PACKAGER_HOSTNAME=$(ip addr show eth0 | grep -oP '(?<=inet\s)\d+(\.\d+){3}')

and...

• used same version of platform-tools on both windows and ubuntu
• used adb kill-server && adb -a -P 5037 nodaemon server start on Windows side after emulator loaded

versions...

• Windows 11 and Ubuntu 20.04
• expo-cli 5.4.3
• last version of node and npm (v16.15.0 - v8.8.0)
• emulator running avd Pixel_4_API_30 with Google APIs
• usb debug mode enabled on emulator
• adb version 1.0.41 and platform-tools 33.0.1

Thanks, @luizwhite , it really helped. It was the easiest one I found on the internet so far 😊 . Let's wait for someone who got some ideas about it.

@luizwhite thanks a lot! Your solution works like a charm. That's what I was searching for. 🍺

For the proxy to work properly with socat. still need to run npx react-native start --host 0.0.0.0 without 127.0.0.1

Wonderful!

I had the experience of successfully setting up and running react native applications on WSL + Windows AVD emulator with using socat command. But recently I moved to a new computer and did everything as it was on the last machine, only with a newer SDK and tools versions and after running the adb devices command on the WSL, I get this error
adb: failed to check server version: protocol fault (couldn't read status): Success
while windows adb server and socat command run successfully.
And when I kill the socat process, adb devices command works well, but without seeing the windows emulator for sure.
All SDK and tool versions are the same on Windows and WSL.
Can someone help me figure out what it is?

socat log for the adb devices query

2022/07/26 17:28:34 socat[2129] N opening connection to AF=2 172.17.96.1:5037
2022/07/26 17:29:07 socat[2129] E connect(5, AF=2 172.17.96.1:5037, 16): Connection timed out
2022/07/26 17:29:07 socat[2129] N exit(1)

upd: solved by adding the firewall rule for adb.exe

and adjust directory structure, see here

Wish this section was more clear.

I had problems using expo and the solution @luizwhite gave worked for me.

So, I successfully overrode that with sudo ln -s /mnt/c/Android/Sdk/platform-tools/adb.exe ~/Android/sdk/platform-tools/adb after backing up the original ubuntu adb executable (just fix that path with your windows adb path and your possible custom ubuntu adb path)

However, I'm concerned there could be any kind of performance issues due to WSL2 accessing Windows memory. It would be great if anyone could point out if it could become an issue going forward.

@luizwhite I was able to connect the emulator. However when I run npx expo start --android I get this error. The Expo-*.apk exists in the directory. Any idea?

NVM, I was able to install the apk with: adb install Exponent-2.28.6.apk.

Having issue with npx expo start
Getting error: could not connect to TCP port 5554: Connection refused.

Set environment variables

export WSL_HOST=$(tail -1 /etc/resolv.conf | cut -d' ' -f2)
export ADB_SERVER_SOCKET=tcp:$WSL_HOST:5037
export ANDROID_SERIAL=emulator-5554
export REACT_NATIVE_PACKAGER_HOSTNAME=$(ip addr show eth0 | grep -oP '(?<=inet\s)\d+(\.\d+){3}')

Starting adb in Windows, emulator was started before

> adb -a nodaemon -P 5037 server start
adb.exe I 05-24 10:56:45 20016 16472 auth.cpp:416] adb_auth_init...
adb.exe I 05-24 10:56:45 20016 16472 auth.cpp:152] loaded new key from 'C:\Users\***\.android\adbkey' with fingerprint A7A3F84B061B063E11EFD5034A7C67ED92AA52C7AA569BE5BEE9BD597E01DDB2
adb.exe I 05-24 10:56:45 20016  5140 transport.cpp:335] emulator-5554: read thread spawning
adb.exe I 05-24 10:56:45 20016 17240 transport.cpp:307] emulator-5554: write thread spawning
adb.exe I 05-24 10:56:45 20016 16472 adb.cpp:173] emulator-5554: already offline

adb in WSL

> adb devices
List of devices attached
emulator-5554   device

> adb shell
emu64xa:/ $