CloudLab: Troubleshooting

Written by Michael Sevilla

Below are some frequently asked questions and solutions for CloudLab:

Docker Permission Denied Error

~$ docker ps
Got permission denied while trying to connect to the Docker daemon socket at unix:///var/run/docker.sock: Get http://%2Fvar%2Frun%2Fdocker.sock/v1.37/containers/json: dial unix /var/run/docker.sock: connect: permission denied

Solution: add the user to the Docker group:

~$ sudo usermod -aG docker ${USER}
~$ exit
~$ ssh <CLOUDLAB NODE>
~$ docker ps
CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS              PORTS               NAMES

Out of space

On the Wisconsin nodes, the / directory is mounted on a 16GB partition. With larger Docker images (the compiled Ceph binaries can be close to 7GB) this can cause out of space issues.

Solution: we can use the extra disk for Docker data:

~$ sudo mkfs.ext4 /dev/sdb
~$ sudo mkdir -p /mnt/sdb/home
~$ sudo mount /dev/sdb /mnt/sdb
~$ sudo chown ${USER}:`id -g -n ${USER}` /mnt/sdb/home
~$ sudo service docker stop
~$ sudo mv /var/lib/docker/ /mnt/sdb/docker
~$ sudo ln -s /mnt/sdb/docker/ /var/lib/docker
~$ sudo service docker start

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