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ViewsHow to disable network for a running Docker container?
I would like to start a Docker container normally, run it, install some things into it, and then I would like to disable the network, to run some more commands in it, but they should not have access to the network. How can I do that for a running container?
I use docker-py and I know I can use network_disabled to disable networking for the whole container. But I am not sure how I can disable the network after the container is already created. Ideally, I would run the container with command sleep infinity, then docker exec some commands in it, then disable networking, then run few more commands using docker exec.
2 answers
Answer question0
Maybe an option would be docker network disconnect
Description
Disconnect a container from a network
Usage
docker network disconnect [OPTIONS] NETWORK CONTAINER
Example:
Create a container attached to the default bridge network
docker container run --rm -it alpine ping 8.8.8.8
and after a while disconnect it with:
docker network disconnect bridge <container-name>
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The standard pattern you should use here is to write a Dockerfile that does whatever software installation you need, and builds an image out of it. This actually fits your immediate need quite nicely, since once you've built the image you can run it without network.
A typical Dockerfile skeleton might look more or less like
FROM ubuntu:18.04
RUN apt-get update \
&& DEBIAN_FRONTEND=noninteractive \
apt-get install --no-install-recommends --assume-yes \
thing-to-run-without-network
CMD ["/usr/bin/thing-to-run-without-network"]
And then you'd build and run it as
docker build -t no-net-test .
docker run --rm --net none no-net-test
Generally you should set your image up so that docker run does everything the container needs to do, without needing to docker exec ever (except for hand debugging). You should never install things into a running container: your work will get lost as soon as you docker rm the container, and deleting and restarting your containers is extremely routine.