I'm unable to get a docker image from ACR in app service that lives in a different subscription.
To Reproduce
Create ACR in one subscription, add container
Add Web App for Containers in another subscription
Since the ACR won't show up in the Web App dropdown menu, enter connection details in private registry tab and save
Exit and re-enter container settings
The settings were moved to the Azure Container Registry tab and are not working => no image is being deployed
Expected behavior
The settings should stay in the private registry tab and a container should be pulled from ACR.
Setting the DOCKER_REGISTRY_SERVER_URL, DOCKER_REGISTRY_SERVER_USERNAME & DOCKER_REGISTRY_SERVER_PASSWORD values in the app config directly does not work.
Any relevant environment information
Azure Portal
Additional context
Issue is also being discussed here https://github.com/Azure/acr/issues/345 and here https://github.com/microsoft/vscode-docker/issues/743

