Issues with Docker

Issue

Dead container cannot be deleted.

If you see the error message something like this:

Error response from daemon: Cannot destroy container elated_wozniak: Driver devicemapper failed to remove root filesystem 656cfd09aee399c8ae8c8d3e735fe48d70be6672773616e15579c8de18e2a3b3: Device is Busy

Restart:

$ umount /var/lib/docker/devicemapper/mnt/656cfd09aee399c8ae8c8d3e735fe48d70be6672773616e15579c8de18e2a3b3

You can delete dead containers with the command:

$ docker rm $(docker ps --all -q -f status=dead)

Error:

Error response from daemon: driver "overlay" failed to remove root filesystem for : remove /var/lib/docker/overlay//merged: device or resource busy

Check what other processes also use docker resources:
```
$ grep docker /proc/*/mountinfo
```

Find the process, that will output something like the following, where the figure after /proc/ equals pid:

/proc/10001/mountinfo:179...
/proc/10002/mountinfo:149...
/proc/12345/mountinfo:159 149 0:36 / /var/lib/docker/overlay/...

Check the process name above pid:

$ ps -p 10001 -o comm=
dockerd
$ ps -p 10002 -o comm=
docker-containe
$ ps -p 12345 -o comm=
nginx   <<<-- This is suspicious!!!

Nginx with pid 12345 also uses /var/lib/docker/overlay/... so we cannot delete the associated container and get the error device or resource busy.
Stop Nginx:
```
$ service nginx stop
```
Delete the container:
```
$ docker rm <container-id>
```
Start the process:
```
$ service nginx start
```

We recommend that you restart the system if there are many processes.