Open Stack

Here is a bit more context.

Currently, at k8s and swarm bay, some required binaries (i.e. etcd and flannel) are built into image and run at host. We are exploring the possibility to containerize some of these system components. The rationales are (i) it is infeasible to build custom packages into an atomic image and (ii) it is infeasible to upgrade individual component. For example, if there is a bug in current version of flannel and we know the bug was fixed in the next version, we need to upgrade flannel by building a new image, which is a tedious process.

To containerize flannel, we need a second docker daemon, called docker-bootstrap [1]. In this setup, pods are running on the main docker daemon, and flannel and etcd are running on the second docker daemon. The reason is that flannel needs to manage the network of the main docker daemon, so it needs to run on a separated daemon.

Daneyon, I think it requires separated storage because it needs to run a separated docker daemon (unless there is a way to make two docker daemons share the same storage).

Wanghua, is it possible to leverage Cinder volume for that. Leveraging external storage is always preferred [2].

[1] http://kubernetes.io/v1.1/docs/getting-started-guides/docker-multinode.html#bootstrap-docker
[2] http://www.projectatomic.io/docs/docker-storage-recommendation/

Best regards,
Hongbin

From: Daneyon Hansen (danehans) [mailto:danehans at cisco.com]
Sent: November-25-15 11:10 AM
To: OpenStack Development Mailing List (not for usage questions)
Subject: Re: [openstack-dev] [magnum]storage for docker-bootstrap



From: 王华 <wanghua.humble at gmail.com<mailto:wanghua.humble at gmail.com>>
Reply-To: "OpenStack Development Mailing List (not for usage questions)" <openstack-dev at lists.openstack.org<mailto:openstack-dev at lists.openstack.org>>
Date: Wednesday, November 25, 2015 at 5:00 AM
To: "OpenStack Development Mailing List (not for usage questions)" <openstack-dev at lists.openstack.org<mailto:openstack-dev at lists.openstack.org>>
Subject: [openstack-dev] [magnum]storage for docker-bootstrap

Hi all,

I am working on containerizing etcd and flannel. But I met a problem. As described in [1], we need a docker-bootstrap. Docker and docker-bootstrap can not use the same storage, so we need some disk space for it.

I reviewed [1] and I do not see where the bootstrap docker instance requires separate storage.

The docker in master node stores data in /dev/mapper/atomicos-docker--data and metadata in /dev/mapper/atomicos-docker--meta. The disk space left is too same for docker-bootstrap. Even if the root_gb of the instance flavor is 20G, only 8G can be used in our image. I want to make it bigger. One way is we can add the disk space left in the vda as vda3 into atomicos vg after the instance starts and we allocate two logic volumes for docker-bootstrap. Another way is when we create the image, we allocate two logic volumes for docker-bootstrap. The second way has a advantage. It doesn't have to make filesystem when the instance is created which is time consuming.

What is your opinion?

Best Regards
Wanghua

[1] http://kubernetes.io/v1.1/docs/getting-started-guides/docker-multinode/master.html
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