Docker, host-OS restart and busy ports

Question

I started learning docker and I use it on Linux ubuntuserver 4.15.0-34-generic. I created container by this command:

sudo docker run -d --privileged --name FBSServer --hostname BACKUPSERVER --restart=always -p 4530:4530 -p 4531:4531 -v /home/adminek/synology:/fbs ferro/backupsystem FBS_Server

As you see container is listening on ports 4530 and 4531. When I ran this command for the first time, everything was OK. The container is running and I can communicate with an app using ports 4530/4531.

But after rebooting the host system the container is in Exited state

root@ubuntuserver:~# docker ps -a
CONTAINER ID        IMAGE                COMMAND                  CREATED             STATUS                            PORTS               NAMES
6e77a4729847        ferro/backupsystem   "/start.sh FBS_Server"   7 hours ago         Exited (128) About a minute ago                       FBSServer

and I can not start the container. I see this:

root@ubuntuserver:~# docker container start FBSServer
Error response from daemon: driver failed programming external connectivity on endpoint FBSServer (c2afb35a61a18c65e8c306bbf36d4e2c9cdf428aafa386e12281d2d9e714b238): Error starting userland proxy: listen tcp 0.0.0.0:4531: bind: address already in use
Error: failed to start containers: FBSServer

In order to start I have to type these commands:

root@ubuntuserver:~# lsof -i :4530 | grep LISTEN
docker-pr 1328 root    4u  IPv6  35086      0t0  TCP *:4530 (LISTEN)
root@ubuntuserver:~# lsof -i :4531 | grep LISTEN
docker-pr 1316 root    4u  IPv6  35059      0t0  TCP *:4531 (LISTEN)

Then I kill the processes (in this example 1328 and 1316) and then I can start container by typing:

docker container start FBSServer

So the question number 1: Why after rebooting host system ports are "busy"?

and number 2: Why sometimes after rebooting host system I see that the changes in container were not saved? In other words - after reboot and made commands from above container is up, but it is in state without last changes I made a while before reboot the host.

Answer 1

Try restarting your docker service after , sudo /etc/init.d/docker restart it should resolve the problem

Answer 2

Normally if your docker container is starting automatically and allocating some port, you added by mistake the option --restart to start containers automatically.

So If after you restart the docker service, the docker-pr service allocates the port of some container, your container is starting automatically.

After starting the docker, to check if you have some container running use:

docker ps

To stop this container, we can use:

docker stop container_name

If you have more than one container, we can use:

docker stop $(docker ps -a -q)

Normally, if you have some container starting automatically, you set this using docker --restart we need to remove it from the auto restart.

To do this use the following command:

docker update --restart=no container_name

After this, you will able to restart your docker service and you will not found any container starting automatically.