docker restart a container will change the port mapping

[cc272309126]

Hi，

after docker restart containerid，it will allocate a new port to the container，Is there a way hold the port for a container？or this is feature for docker?
reproduce steps
1，docker run -d -p 8080 imageid
2，docker restart containerid
3，compare the container the mapping port，you will found that the port is changed。

ps: on docker 1.2.0 after restart the container twice，the port will lost. but this issue can not be reproduced on docker docker-1.3.0-dev.
thanks

[cpuguy83]

@cc272309126 1.3.0-dev would be master.
Did you try on 1.3.0, which was released last week?

[cc272309126]

@cpuguy83 on 1.3.0 after restart the container the mapping port still changed, After I read the code, I found that restarting the container will allocate the mapping port again unless allocating a port for container manual. so I think maybe that's designing. and the mapping port lost has been fixed.

[hcguersoy]

I'm running into issues due to this behavior: I'm running a lot of containers on the hosts and sometimes (e.g. due to provisioning runs) the docker daemon is restarted. After this, all port mappings are different.
It would be nice if a container should preserve its used ports after an restart.

[cc272309126]

@hcguersoy do you specify a host port mapping to a container port like "docker run -d -p 1234:1234 image command"?

[hcguersoy]

Hi,

sorry for my late answer...

No, I don't. But I would expect that a restarted container uses the same ports again.
Maybe I'm wrong ;-)

[gdm85]

I have also been hit by this bug, and it's a deployment blocker for me.

Although in production one will want to use fixed port mappings, there are scenarios (development, testing, staging) where you want containers to survive a daemon/host reboot and keep their port mapping, if not just to not destroy the work-flow of all involved people that are still using the containers.

[gdm85]

I have implemented stateful hostconfig save/restore in my docker-fw utility, feel free to give it a shot.

[jessfraz]

closing as dup of #7158 which is why it gets another port

[jessfraz]

also #9047 for reference