Permission Denied While Trying to Connect to the Docker Daemon Socket

Out of the blue today, my first day back after Christmas break, I got this when running a GH Actions Workflow on one of our Self-Hosted Linux Runners 😱:

It had been running fine prior to my break so what gives? I started to investigate…

I logged in to the Linux VM where this particular Self-Hosted Runner is hosted with the same credentials as used when I installed the Self-Hosted Runner originally. I used the following command to confirm the same outcome:

docker ps

Yup, same thing.

The next configuration I wanted to check was whether this user is a member of the docker group so I used this command:

sudo groups <user>

Mmmmm, that’s odd. This user wasn’t a member and therefore begs the question, how did this ever work in the first place?!!

I added this user using this command:

sudo usermod -a -G docker <user>

I ran docker ps again but still no dice. 🤔.

I then checked the status of the docker service using this command:

sudo systemctl status docker

It reported:

Ok, what next? 🤔

I decided to restart the self-hosted service so I entered these commands:

cd actions-runner
sudo ./svc.sh start

This is when I saw these failures:

I restarted the Self-Hosted Runner using these commands:

sudo ./svc.sh stop
sudo ./svc.sh start

Then I logged out and back in again to confirm docker access docker ps and finished off by re-running the failed GH Action Workflow. 🥳 Equilibrium is once again restored. As per protocol, I shared issue and resolution with our IT Team in case this crops up again when I’m not online to help.