Using webpacker (webpack-dev-server) to compile inside a docker container without rebuilding
I'm not too familiar w/ webpacker but looking at your configs my guess is that you use 0.0.0.0:3035 address to access dev-server assets from within your web container when it should be webpacker:3035.
Try to update WEBPACKER_DEV_SERVER_HOST in your web service config:
web: ... environment: ... - WEBPACKER_DEV_SERVER_HOST=webpacker