Documentation dockerdYou must connect to the correct host .

1) Connect to the correct host

ssh cks000037

sudo -i

2) Remove user developer from the docker group ONLY

2.1 Verify current groups (optional but fast)

id developer

2.2 Remove ONLY from docker group

gpasswd -d developer docker

2.3 Verify removal

id developer

✅ docker should not appear; other groups must remain.

3) Reconfigure Docker to secure the socket and disable TCP

Docker config file:

vi /etc/docker/daemon.json

3.1 Set socket group to root and disable TCP listeners

Ensure the file contains exactly these relevant settings (merge with existing JSON if present):

{

"group": "root",

"hosts": ["unix:///var/run/docker.sock"]

}

Important:

"group": "root" → docker.sock owned by group root

"hosts" includes ONLY the unix socket (no tcp://)

If the file already exists with other keys, add/adjust only these keys and keep valid JSON (commas!).

Save and exit:

wq

4) Restart Docker daemon

systemctl daemon-reload

systemctl restart docker

systemctl status docker --no-pager

5) Verify Docker socket ownership and permissions

ls -l /var/run/docker.sock

Expected:

srw-rw---- 1 root root ...

✅ Owner: root

✅ Group: root

6) Verify Docker is NOT listening on TCP

ss -lntp | grep docker

Expected:

No output (or nothing bound to TCP by dockerd)

Optional double-check:

ps aux | grep dockerd | grep -v grep

Ensure no -H tcp://... flags.

7) Ensure Kubernetes cluster is healthy

7.1 Check node and pods

export KUBECONFIG=/etc/kubernetes/admin.conf

kubectl get nodes

kubectl get pods -A

All nodes should be Ready, core pods Running.