I am running Ubuntu Server 20.04.2, fresh install. I have an unbound container up and running, also a pihole container.

After a reboot of the host server, Docker doesn't show me any containers at all. And no docker images either.

But the unbound and pihole containers are definitely running in the background. The pihole website is accessible via the hosts IP, and DNS requests from clients are handled without problems.
I have no output from "docker ps", "docker ps -a", "docker images" and "docker stats".

I can also see that the listening ports are blocked by "docker-pr"

Can anybody help me? How do I access those "invisible" containers?

"sudo systemctl restart docker" didn't bring any change, also tried the commands above as root.

$ docker -v 

Docker version 20.10.3, build 48d30b5

$ which docker

/usr/bin/docker

$ apt list --installed | grep 'docker'

docker-ce-cli/focal,now 5:20.10.3~3-0~ubuntu-focal amd64 [installed,automatic]

docker-ce-rootless-extras/focal,now 5:20.10.3~3-0~ubuntu-focal amd64 [installed,automatic]

docker-ce/focal,now 5:20.10.3~3-0~ubuntu-focal amd64 [installed]

$ snap list

Name    Version      Rev    Tracking       Publisher   Notes

core    16-2.48.2.1  10823  latest/stable  canonical✓  core

core18  20200707     1880   latest/stable  canonical✓  base

docker  19.03.11     471    latest/stable  canonical✓  -

lxd     4.0.2        16099  4.0/stable/…   canonical✓  -

snapd   2.45.2       8542   latest/stable  canonical✓  snapd

$ docker info

Client:

 Context:    default

 Debug Mode: false

 Plugins:

  app: Docker App (Docker Inc., v0.9.1-beta3)

  buildx: Build with BuildKit (Docker Inc., v0.5.1-docker)



Server:

 Containers: 0

  Running: 0

  Paused: 0

  Stopped: 0

 Images: 0

 Server Version: 19.03.11

 Storage Driver: overlay2

  Backing Filesystem: extfs

  Supports d_type: true

  Native Overlay Diff: true

 Logging Driver: json-file

 Cgroup Driver: cgroupfs

 Plugins:

  Volume: local

  Network: bridge host ipvlan macvlan null overlay

  Log: awslogs fluentd gcplogs gelf journald json-file local logentries splunk syslog

 Swarm: inactive

 Runtimes: runc

 Default Runtime: runc

 Init Binary: docker-init

 containerd version: 7ad184331fa3e55e52b890ea95e65ba581ae3429

 runc version: 

 init version: fec3683

 Security Options:

  apparmor

  seccomp

   Profile: default

 Kernel Version: 5.4.0-65-generic

 Operating System: Ubuntu Core 16

 OSType: linux

 Architecture: x86_64

 CPUs: 4

 Total Memory: 7.69GiB

 Name: ubuntu

 ID: W56I:F32Q:H7O6:LWFT:AAUC:6QEI:EYOZ:HFJB:IEQ3:T6E7:ZCJG:HSJU

 Docker Root Dir: /var/snap/docker/common/var-lib-docker

 Debug Mode: false

 Registry: https://index.docker.io/v1/

 Labels:

 Experimental: false

 Insecure Registries:

  127.0.0.0/8

 Live Restore Enabled: false