Ubuntu container keep restarting

Question

I'm using docker-compose to add a new ubuntu container but the container keeps restarting and I don't know why... any clue of what I can check ?

here my docker-compose service:

  ubuntu:
    image: ubuntu
    container_name: ubuntu
    network_mode: host
    restart: unless-stopped
    volumes:
      - /mnt:/NAS:rw
    environment:
      - TZ="Asia/Shanghai"

and here is the docker ps output:

CONTAINER ID        IMAGE               COMMAND                  CREATED             STATUS                          PORTS                                            NAMES
6c084528838c        ubuntu              "/bin/bash"              6 minutes ago       Restarting (0) 18 seconds ago                                                    ubuntu

i'm using Docker 17.09 on Ubuntu server 17.04 and I'm running the container with this alias:

alias dcrun='docker-compose -f /home/docker-compose.yml'

dcrun up -d ubuntu

Thank you

Answer 1

This is quite expected since you haven't defined any command: or entrypoint: in the docker compose.

Ubuntu image by default has bash command as CMD which isn't really a foreground process. Ref - https://github.com/dockerfile/ubuntu/blob/master/Dockerfile

If you run it in interactive mode(-i), you will dive into bash automatically -

$ docker run -it ubuntu 
root@8d6ac0591d88:/# 

Hence, once the bash command exits your container also dies but due to your restart: unless-stopped policy, Docker daemon keeps trying to restart it.

If you want your container to be up & running with compose, try defining a foreground process as below -

  ubuntu:
    image: ubuntu
    container_name: ubuntu
    network_mode: host
    restart: unless-stopped
    volumes:
      - /mnt:/NAS:rw
    environment:
      - TZ="Asia/Shanghai"
    command: "tail -f /dev/null"

Your container will not restart now -

$ docker ps
CONTAINER ID        IMAGE                              COMMAND                  CREATED             STATUS                      PORTS                     NAMES
cee860adf641        ubuntu                             "tail -f /dev/null"      5 seconds ago       Up 3 seconds                                          ubuntu