Red Hat Bugzilla – Bug 1293502
Docker spawns a docker-proxy process for each port in a container
Last modified: 2016-03-31 19:23:11 EDT
Description of problem: Docker spawns a docker-proxy process for each port in a container. Consider the usage of asterisk in a container. This required the opening of hundreds, if not thousands of ports. This can cause the docker host to crash. docker run -it --rm=true --name porttest -p 3000-3010 busybox In another shell: ps ax | grep docker-proxy | egrep '30[0-9]{2}' | wc Should yield 11 processes. If this is increased, such as: docker run -it --rm=true --name porttest -p 3000-4000 busybox Your docker host may destabilise, crash or freeze. How reproducible: Always Actual results: Docker host crashes from the number of spawned processes Expected results: Docker host should not crash or freeze, and there should be one docker-proxy for each running container.
Wasn't there an option to use iptables instead of the userland port proxy?
Enabling hairpin NAT via the daemon flag "--userland-proxy=false" prevents the daemon from spawning docker-proxy processes. This way the port mapping is achieved via just iptables (as Mrunal said). Are there any reasons you can't disable userland-proxy? Could you try setting "--userland-proxy=false" and see if the daemon still has issues?
I believe that using the iptables rules prevents container to container communication.
could you tell me how you reproduce the blocked container to container communication?
Here is the information I was sent: """ Well, to explain it better, take a host that's on 192.168.0.1, running a Docker container listening on port 5000 (in the container) that's exposed on port 800 on the host. Assume that the first container's Docker IP is 172.17.0.1. Then, take another Docker container on the same host trying to connect to that exposed port; APP=`docker run -d -p 800:5000/tcp training/webapp python app.py` curl http://192.168.0.1:800/ # works, of course docker run --rm -it image curl http://192.168.0.1:800/ # does not work docker run --rm -it image curl http://172.17.0.1:5000/ # does work docker stop $APP docker rm $APP """ I haven't tried this myself yet however.
In docker-1.9.1-23.el7.x86_64, move to verified. Just to be noted, It's better not try `docker run -it --rm=true --name porttest -p 3000-4000 busybox` in remote machine which used network is not strong enough.
Since the problem described in this bug report should be resolved in a recent advisory, it has been closed with a resolution of ERRATA. For information on the advisory, and where to find the updated files, follow the link below. If the solution does not work for you, open a new bug report. https://rhn.redhat.com/errata/RHBA-2016-0536.html