I’m testing to run a Vaadin Flow app 24.9.12 in a docker container in development mode. But when I access is from the browser on my host machine, the dev tools are not loaded. It says “Dev tools functionality denied for this host.”. When running the same app on the host itself with exactly the same code, Dev tools are properly loaded. I tried different options for the vaadin.devmode.hostsAllowed property, (vaadin.devmode.hostsAllowed=localhost,127.0.0.1,0.0.0.0,host.docker.internal) but nothing really works.
If you set the log level to DEBUG for com.vaadin.flow.server-communication.IndexHtmlRequestHandler you should see what IP is rejected (given it’s docker I would not be surprised if it’s some 172.x.x.x).
Another option is to set vaadin.devmode.hostsAllowed=* that should allow everything.