Proxies for Docker
Three separate places take a proxy setting here, and configuring the wrong one is the usual reason nothing changes.
Three separate settings
Pulling images uses the daemon configuration. Building uses build arguments. A running container uses its own environment.
Setting one and expecting the others to follow is the mistake that costs an afternoon.
The exclusion list is required
Calls between containers must bypass the intermediary. Without an exclusion list they travel out and back, which is slow at best and broken at worst.
Write the list at the same time as the proxy setting, never afterwards.
Verify from inside
Run one request to an address-reporting service from inside the container. That is the only check that proves the setting reached where you meant it to.
Restarts
The daemon needs restarting after its configuration changes. Containers need recreating, and restarting them is not the same thing.
docker build --build-arg HTTP_PROXY=$PROXY . docker run -e HTTP_PROXY=$PROXY -e NO_PROXY=localhost,db image