docker connect to local mongo
ENV MONGO_HOST "host.docker.internal"
//https://tsmx.net/docker-local-mongodb/
You can use: 172.17.0.1 as it is the default host ip that the containers can see. But you need to configure Mongo to listen to 0.0.0.0.
From docker 18.03 onwards the recommendation is to connect to the special DNS name host.docker.internal
For previous versions you can use DNS names docker.for.mac.localhost or docker.for.windows.localhost.