docker-expo

Dockerized Expo application for making cross-platform mobile apps.

Watchman not included anymore

This docker container used to have facebook/watchman installed, but it seems to have became unneeded. These days changes in files are detected, even when expo is running inside docker container. Old Dockerfile has been renamed to Dockerfile-watchman, if anyone finds urge to use it. However facebook/watchman ( https://github.com/facebook/watchman ) has also received updates, so old dockerfile and my kerbe/watchman docker image doesn't work properly.

Usage of this Docker container

Expo has changed it's expo-cli tooling, and moved from global expo-cli to project based install. Current best practice is to run npx expo start, and using expo-cli gives warning. This docker container is able to work in both modes, examples given below.

Old expo-cli way

You pull this container, and then you have expo-cli in your possession. You can either init your project with container, or with expo-cli installed on your computer directly.

Running expo development environment is done like this (command works in WSL, adjust accordingly if you use PowerShell or CMD while in Windows):

docker run -it --rm -p 19000:19000 -p 19001:19001 -v "$PWD:/app" \
-e REACT_NATIVE_PACKAGER_HOSTNAME=192.168.1.101 \
--name=expo kerbe/expo start

Here port 19000 is for actual application port, which needs to be open for your mobile. Port 19001 is default Metro Bundler port.

Set REACT_NATIVE_PACKAGER_HOSTNAME to be your local IP address. If that is not set, Expo will bind to Docker container local IP. That IP isn't accessible for your mobile phone, even if it is in same WLAN.

Setting name for container makes it easier to work with further docker commands.

New npx expo way

Create small runner script in your application project root, named apprunner.sh:

#!/bin/bash
npx expo start

Then give it run permissions: chmod +x ./apprunner.sh

Now you can overwrite default entrypoint with following:

docker run -it --rm -p 19000:19000 -p 19001:19001 -v "$PWD:/app" \
-e REACT_NATIVE_PACKAGER_HOSTNAME=192.168.1.101 \
--name=expo --entrypoint "./apprunner.sh" kerbe/expo

Rest of the info from old expo-cli way applies.

Contributing

Having problems with this image? Want to improve it somehow? Open issue or pull request!