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kolla
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kolla/specs/kubernetes-deployment.rst

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Deploy Kolla images with Kubernetes

https://blueprints.launchpad.net/kolla/+spec/kolla-kubernetes

Kubernetes was evaluated by the Kolla team in the first two months of the project and it was found to be problematic because it did not support net=host, pid=host, and --privileged features of docker. Since then, it has developed these features. (https://github.com/kubernetes/kubernetes/releases/tag/v1.2.0)

Though Kolla deploys the containers using Ansible, we can leverage the current work by using the config generation and injecting the configs into the Kubernetes pod.

Problem description

Kubernetes - life-cycle management: service monitoring, restarting, and scaling - upgrades: rolling and all at once upgrades

Kubernetes has services/tools that can provide service monitoring, health checks, service scaling, and upgrades.

We can use the scheduler to assign work loads to appropriate nodes. Kubernetes has built in health checks that will maintain the container's status. And we can use the replication processes[1] to scale up and down our stack.

For upgrades, Kubernetes has a tool called 'deployments'[2], which will detect when there is a config change in the container and start scaling down the current running container and scaling up the new container. If the new container fails, it can roll back, a nice feature containers provide for us. Though this is oversimplified for OpenStack, we can make use of this.

Proposed change

  • Add a deployment specific git repo (kolla-kubernetes) to contain the Kubernetes deployment code.

Bootstrapping

Kubernetes provides RestartPolicy which allows to define whether a container should be restarted and when[3]. It may be used for bootstraping.

Another alternative is Ansible, which runs a number of scripts to setup the database, keystone, etc..

Security impact

The deployed OpenStack’s security should not be affected by the deployment tool. In addition, if we containerize the config data so that it can be injected into a pod, we can leverage the selinux capabilities in the config container.

Performance Impact

Unknown

Implementation

Primary Assignee(s) ----------- Ryan Hallisey (rhallisey)

Other contributor(s):

Michal Rostecki (mrostecki) Swapnil Kulkarni (coolsvap) MD NADEEM (mail2nadeem92) Vikram Hosakote (vhosakot) <Please add your name here if you are getting involved in kolla-kubernetes>

Milestones

Target Milestone for completion:

unknown

Work Items

  1. Change start.yml files so that they can inject configs into Kubernetes pod.
  2. Add support for kolla-kubernetes to kolla-cli.

Testing

Functional tests will be implemented in the OpenStack check/gating system to automatically checks that the Kubernetes deployment works for an AIO environment.

Documentation Impact

Add a quick start guide which will explain how to deploy kolla-kubernetes. Add a develop guide on how to contribute, which also explains how the deployment works.

References