Docker – Restart docker container in privileged mode

dockerproc

I have a docker container that is not coping with the load.

I need increase the value in /proc/sys/net/core/somaxconn but I'm unable to do so because the container is not running in privileged mode.

Since creating the docker file, there have been several tweaks to the nignx and php configurations.

Is it possible to restart the container with privileged mode without losing the configuration changes I've already made?

Best Answer

The container configuration is in /var/lib/docker/containers/<id>/hostconfig.json - you can edit it and restart your container, but docker shouldn't be running when you edit it.

# docker run -ti --name test fedora:25 /bin/bash
# echo 512 > /proc/sys/net/core/somaxconn   # in docker
bash: /proc/sys/net/core/somaxconn: Read-only file system
# exit # exit docker, back to host
# systemctl stop docker # or stop it with whatever servicemanager you're using

# cd /var/lib/docker/containers/b48fcbce0ab29749160e5677e3e9fe07cc704b47e84f7978fa74584f6d9d3c40/
# cp hostconfig.json{,.bak}
# cat hostconfig.json.bak | jq '.Privileged=true' | jq '.SecurityOpt=["label=disable"]' > hostconfig.json

# systemctl start docker
# docker start test
test
# docker exec -ti test /bin/bash
# echo 512 > /proc/sys/net/core/somaxconn   # in docker, now works

This will off course shut down all containers while you're making the changes.

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