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I have the following systemd script:
[Unit]
Description=Hub docker container
After=docker.service
[Service]
User=root
ExecStart=/home/hub/hub.sh
ExecStop=/bin/docker stop hub
ExecStopPost=/bin/docker rm hub
[Install]
WantedBy=multi-user.target
Running the command: systemctl start/stop hub works fine. I also created the symlink by using systemctl enable hub. Why doesn't my service start up after I reboot the entire laptop? I followed the docker guide so that Docker starts up on reboot, but for some reason my container doesn't start up. Am I missing a field in my script?
The command I am using my ExecStart, "/home/hub/hub.sh" script is:
docker run --net=host --restart=always --name hub -t hub
After reboot I get the following when I type systemctl status hub:
● hub.service - Hub docker container
Loaded: loaded (/etc/systemd/system/hub.service; enabled; vendor preset: disabled)
Active: inactive (dead)
509
Docker provides restart policies to control whether your containers start automatically when they exit, or when Docker restarts. Restart policies ensure that linked containers are started in the correct order. Docker recommends that you use restart policies, and avoid using process managers to start containers.
Containers will be stopped. Any modifications to the container will still be present when the container next starts, which will happen automatically when the docker daemon starts if -r=true is provided as mentioned above.
Docker also lets the user set the restart policy upon exit or failure. Users can type docker ps to check if the restart policy is active; it will be shown as either Up , when the container is up and running, or Restarting when the container is in the restart state.
In my case, I already had the containers set to restart=always (btw you can inspect a container's restart policy with docker inspect -f "{{ .HostConfig.RestartPolicy.Name }}" <container> and/or change it with docker update --restart=always <container>) but the containers still were not starting up until I ran a command like docker ps.
It turns out that the socket was enabled in systemd, but the service itself was disabled and so wouldn't start until a command was issued against it.
Inspecting via systemctl status docker.socket and systemctl status docker.service verified this:
root@poke:~# systemctl status docker.socket
● docker.socket - Docker Socket for the API
Loaded: loaded (/lib/systemd/system/docker.socket; enabled; vendor preset: enabled)
Active: active (running) since Thu 2020-07-30 18:28:38 EDT; 18h ago
Listen: /var/run/docker.sock (Stream)
Tasks: 0 (limit: 4647)
CGroup: /system.slice/docker.socket
root@poke:~# systemctl status docker.service
● docker.service - Docker Application Container Engine
Loaded: loaded (/lib/systemd/system/docker.service; disabled; vendor preset: enabled)
Active: active (running) since Fri 2020-07-31 13:19:53 EDT; 5min ago
Docs: https://docs.docker.com
Main PID: 3094 (dockerd)
Tasks: 20
CGroup: /system.slice/docker.service
├─3094 /usr/bin/dockerd -H fd:// --containerd=/run/containerd/containerd.sock
└─3426 /usr/bin/docker-proxy -proto tcp -host-ip 0.0.0.0 -host-port 6379 -container-ip 172.17.0.3 -container-
(Note the "disabled" for docker.service, even though it was running at the time.)
I was able to fix this by running systemctl enable --now docker.service:
root@poke:~# systemctl enable --now docker.service
Synchronizing state of docker.service with SysV service script with /lib/systemd/systemd-sysv-install.
Executing: /lib/systemd/systemd-sysv-install enable docker
Many thanks to this reddit user's reply for tipping me off.
71
In order to start container after reboot you need to add this property: --restart=always to your container start script. For example:
docker run -d -p 80:5000 --restart=always image_name
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