Containers' IpcMode causes containers restart during reconfigure

[Mathieu Gaubert]

When doing a kolla-ansible reconfigure with docker-ce >= 17.09, almost every containers are restarted (except the one with docker HostConfig IpcMode = host), even if there no containers change nor configuration changes.

It seems that docker-ce changed their default behavior about IpcMode default configuration from "" to shareable (will be private in a future version) since docker-ce version 17.09 (https://github.com/docker/docker-ce/commit/eca24fb7b072592bd8ef9b12c368731229d91c1c#diff-4087a9c3e313fc318df0812e1d14a158).

When kolla-ansible compares the containers (Check *** containers task), the module kolla_docker.py compares the IpcMode required by kolla (in most of the case IpcMode is omitted) with the one returned by docker: IpcMode = shareable) and will return changed = true, notifying the Restart <container name> container handler.

This problem does not happen with docker-ce 17.06

This bug was tested on :
Centos 7.4.1708
Docker-ce 17.09 / 17.06
Kolla-Ansible 5.0.1
Kolla containers built from source (5.0.1 on Centos latest image)

The problem will certainly also affect Ubuntu 16.04

[Simon Piette (simon.piette)]

As a workaround, you can explicitly set ipc_mode in docker_common_options, for example:

docker_common_options:
  ipc_mode: "private"

[Martin Chlumsky (martin-chlumsky)]

I have a patch that we use internally to fix this.

We set ipc_mode to 'private' when the docker api version is >'1.32' and no ipc_mode is specified when the kolla_docker module is called.