4.2 KiB
Deploy kolla-kubernetes with Ansible
POC - Ansible support for Mariadb https://review.openstack.org/#/c/334255/
Deploying and upgrading OpenStack is a workflow. Kubernetes is not a workflow engine and it is not meant to act like one. Kubernetes is good at managing containers and Ansible is good at handing off an organized deployment to be managed. Instead of trying to make Kubernetes into something it isn't, the work could be split by two tools that both specialize in their fields.
Problem description
In order to do dependancy management in Kubernetes, it requires logic to be added into containers, pods, and/or etcd, so that services will be cluster aware during orchestration. In doing so it requires the developers to account for all scenarios and corner cases when architecting the containers.
Use Cases
Ansible is capable of handling dependancy management and will be able to orchestrate a cluster and hand it off to Kubernetes to be managed.
Ansible will be orchestrating the cluster by making CLI calls instead of using a custom module. The reason for this is to assist operators by providing an interface to manage any day 1 or day 2 operations by hand.
Arguments
Ansible is an additional tool to add to the project. So there is an additional dependancy here. - Ansible wouldn't be adding any additional complexity. There would actually be a net reduction in complexion because of the logic required to be built into the containers in order to count for all use cases.
Kubernetes will not have complete control over the lifecycle of OpenStack. Ansible will be handeling the bootstrapping, deployment, and the upgrade. - Kubernetes upgrades at the moment only scale down a running container and scale up the new one. OpenStack upgrades are far more complex and require a series of steps to be executes before a service can be successfully upgraded. - Ansible can be removed when the community feels Kubernetes has reached a point where the lifecycle can be fully managed by Kubernetes
< Add any pros/cons here so we can track any thoughts on the whether this is a good choice or not >
Proposed change
Use Ansible to orchestrate pods, service, configmaps, ect.
The CLI will be split out into sub commands that only manage/interact with a single Kubernetes object. Ansible will plug into this interface and orchestrate deployment through this provider.
- Managed by the CLI:
-
configmaps pods replication controllers deployments services < kubernetes_objects > querying Kubernetes objects rendering templates
- Managed by Ansible:
-
OpenStack deployment OpenStack upgrades < additional_workflows >
Dependencies
- Ansible > 2.1
Security impact
The endpoint for the Kubernetes master can be assigned on startup. The community can recommend running anisble on the same host as the Kubernetes master. The Ansible Kubernetes module has an outline for SSL support [1], but it's not fully implemented yet.
Performance Impact
Instead of relying on the CLI as a workflow, Ansible will provide the workflow and make calls to the CLI.
Implementation
Primary Assignee(s) ----------- Ryan Hallisey (rhallisey) Flavio Percoco (flaper87)
- Other contributor(s):
-
kolla-kubernetes team
Work Items
- Merge missing features into Kubernetes Ansible module [2]
- Remodel the CLI into sub tasks to reflect the creation of each type of resource
- Build an Ansible play for each service
- Document how to deploy with Ansible
- Document how an operator would use the CLI to run commands by hand
- Add a dry run option so the operator can see exactly what is going to happen
<Please add new work items that are worth mentioning in the spec>
Documentation Impact
This should simplify the docs. Instead of a bunch of manually CLI steps things will be driven by Ansible. There will be addition docs for operators on how to drive the deployment through the CLI.