Error running cadvisor docker package on Ubuntu 18.04.4 LTS

[NichUK]

I'm trying to run up cadvisor to monitor docker containers on an Ubuntu 18.04.4 LTS machine.

Using the command I got from the cadvisor site:

sudo docker run --volume=/:/rootfs:ro --volume=/var/run:/var/run:ro --volume=/sys:/sys:ro --volume=/var/lib/docker/:/var/lib/docker:ro --volume=/dev/disk/:/dev/disk:ro --publish=8080:8080 --detach=true --name=cadvisor --privileged gcr.io/google-containers/cadvisor:latest

I repeatably get the error:

docker: Error response from daemon: error while creating mount source path '/var/lib/docker': mkdir /var/lib/docker: read-only file system.

My Docker version is 18.09.9 build 1752eb3 and has several containers running successfully on it.

[dashpole]

It looks like cAdvisor is unable to mount /var/lib/docker because its filesystem is read-only. I don't think this is related to cAdvisor. Googling for your error brings up a few issues that may be related. I would start there.

[NichUK]

It's a fresh clean install of Ubuntu, with Docker loaded as part of the install...

If the filesystem is set as read-only by that process, then that would seem to be a default, and if CAdvisor needs non-standard read/write access to it, then surely that's worth a documentation note, if nothing else?

[stevegroom]

The /var/lib/docker directory exists but is not readable to users that are added to the docker group.

ls -las /var/lib
...
4 drwx--x--x 14 root      root      4096 Mar  8 19:59 docker 
...

ls -las /var/run
...
0 drwx------  5 root root    120 Mar  8 19:59 docker
4 -rw-r--r--  1 root root      4 Mar  8 19:59 docker.pid
0 srw-rw----  1 root docker    0 Mar  8 19:59 docker.sock
...

If I run sudo docker... --privileged=true that makes no difference.

[stevegroom]

OK,
I think I have it working now.

Re-reading https://github.com/google/cadvisor/blob/master/docs/running.md#centos-fedora-and-rhel it hints that /var/lib/docker access is not needed when using the privileged=true switch.

I removed /var/lib/docker from my docker-compose file:

  cadvisor:
    image: google/cadvisor:latest
    container_name: cadvisor
    command:
      - privileged=true
    ports:
    - 8081:8080
    volumes:
    - /:/rootfs:ro
    - /var/run:/var/run:ro
    - /sys:/sys:ro
#    - /var/lib/docker/:/var/lib/docker:ro
    - /dev/disk/:/dev/disk:ro

Still have testing to do, but looks promising.

[plaidshirtakos]

I am facing the exact same error.

[Cethy]

FYI, if you install docker w/ snap (on ubuntu 18.04), /var/lib/docker does not exists because docker is set up differently.
To find the actual folder you need, run docker info | grep "Docker Root Dir:" (mine was /var/snap/docker/common/var-lib-docker).

and my docker-compose file:

  cadvisor:
    volumes:
      - /var/snap/docker/common/var-lib-docker:/var/lib/docker:ro