Docker on Ubuntu Core - docker.service not found

Question

I am trying to get docker working on Ubuntu core using snappy to install. I am following this guide.

My VM is behind a proxy but using http_proxy env settings and sudo -E I seem to be able to get snappy to install docker:

(amd64)ubuntu@ubuntu-snappy:~$ snappy list -v
Name          Date       Version   Developer  
ubuntu-core   2016-02-25 16        ubuntu*    
docker        2016-04-18 1.6.2.005 canonical* 
generic-amd64 2016-02-25 1.4       canonical* 
(amd64)ubuntu@ubuntu-snappy:~$

My problems begin when trying to set the proxy for docker daemon. Firstly systemctl doesn't seem to be able to find docker.service:

(amd64)ubuntu@ubuntu-snappy:~$ sudo systemctl status docker
● docker.service
   Loaded: not-found (Reason: No such file or directory)
   Active: inactive (dead)
(amd64)ubuntu@ubuntu-snappy:~$ 

so setting the proxy as described here doesn't seem to have any effect.

Can anyone offer any advice?

(amd64)ubuntu@ubuntu-snappy:~$ cat /etc/os-release 
NAME="Ubuntu"
VERSION="15.04 (Vivid Vervet)"
ID=ubuntu
ID_LIKE=debian
PRETTY_NAME="Ubuntu 15.04"
VERSION_ID="15.04"
HOME_URL="http://www.ubuntu.com/"
SUPPORT_URL="http://help.ubuntu.com/"
BUG_REPORT_URL="http://bugs.launchpad.net/ubuntu/"
(amd64)ubuntu@ubuntu-snappy:~$ uname -a
Linux ubuntu-snappy 3.19.0-51-generic #57-Ubuntu SMP Fri Feb 19 14:05:05 UTC 2016 x86_64 x86_64 x86_64 GNU/Linux
(amd64)ubuntu@ubuntu-snappy:~$ 

Answer 1

I had the exactly the same issue with Ubuntu Core 16 (on raspberry pi 2).

Could you please try the following workaround?

Try to run docker with sudo snap run :

<my-user>@localhost:/home/~ sudo snap run docker login
Login with your Docker ID to push and pull images from Docker Hub. If you don't have a Docker ID, head over to https://hub.docker.com to create one.
Username: <my_user_name>
Password: 
Login Succeeded

<my-user>@localhost:/home/~ sudo snap run docker ps
CONTAINER ID        IMAGE                     COMMAND                  CREATED             STATUS              PORTS               NAMES
7992d18555f1        zsoltm/postgresql-armhf   "/entrypoint.sh postg"   13 minutes ago      Up 13 minutes       5432/tcp            db

Root Cause:

The root cause of this issue seems to be that my user is not part of the docker group and i cannot use usermod to add my user to the docker group because it is Read-only FS (!!) :

<my-user>@localhost:~$ sudo usermod -aG docker <my-user>
usermod: /etc/group.1612: Read-only file system
usermod: cannot lock /etc/group; try again later.

Answer 2

Probably docker isn't running yet (for some reason).
You can try starting docker with sudo snappy activate docker due to how snappy works.