I'm using the "new" (SDK 46) project-scoped Expo CLI in a docker container. Basic flow is:
- Dockerfile from
node:latestruns the Exponpxproject creation script, then copies in some app-specific files CMDisnpx expo start- Using docker-compose to create an instance of the above image with port
19000mapped to local (on a Mac), andEXPO_PACKAGER_PROXY_URLset to my host local IP (see below). I've also mounted a network volume containing my components to the container to enable live edits on those source files.
If you google around, you'll see a few dozen examples of how to run Expo in a docker container (a practice I really believe should be more industry-standard to get better dev-time consistency). These all make reference to various environment variables used to map URLs correctly to the web-based console, etc.. However, as of the release of the new (non-global) CLI, these examples are all out of date.
Using the Expo Go app I've been able to successfully connect to Metro running on the container, after setting EXPO_PACKAGER_PROXY_URL such that the QR code showing up in the terminal directs the Go app to my host on 19000, and then through to the container.
What is not working is live reloading, or even reloading the app at all. To get a change reflected in the app I need to completely restart my container. For whatever reason, Metro does not push an update to the Go app when files are changed (although weirdly I do get a little note on Go saying "Refreshing..." which shows it knows a file has changed). Furthermore, it seems like a lot of the interaction between the app and the container console are also not happening, for example when the Go app loads the initial JS bundle, loading progress is not shown in the console as it is if I try running expo outside of Docker.
At this point my working theory is that this may have something to do with websockets not playing nicely with the container. Unfortunately Expo has so much wrapped under it that it's tough for me to figure out exactly why.
Given that I'm probably not the only one who will encounter this as more people adopt the new CLI and want a consistent dev environment, I'm hoping to crowdsource some debugging ideas to try to get this working!
(Additional note -- wanted to try using a tunnel to see if this fixes things, but ngrok is also quite a pain to get working correctly through docker, so really trying to avoid that if possible!)