Table of Contents generated with DocToc
Hello, world!
Container platforms has become an integral part of modern IT landscape, but the majority of the systems in the world are still built on legacy technologies. Here we introduce a hybrid application model to improve the management efficiency of assets across various platforms (containers, virtual machines, cloud services, ...)
This model is implemented in kubernetes with its Custom Resource technology, and leverages other assets in kubernetes. This leads to the following 2 points
- Hybrid Application Model follows the kubernetes convention in defining resources
- Custom Resources and operators/controllers need to be provided to work with non k8s systems.
The goal of this model is to provide a common way to define resources of hybrid application with their deployment information, so that they can be discovered or distributed across systems and managed in a centralized way.
Term "Application" in this model refers to a group of resources, those resources are managed in various systems (kubernetes, openstack, manageiq, cloud services, ... ) and are represented by native or custom resources in kubernetes. The Application definition from Kubernetes Special Interest Group serves this purpose well, Application is the first resource we introduce into hybrid application model.
In order to model kubernetes resource in a kubernetes system without impacting that kubernetes system, "wrapper" resource are needed. Depending on the actual location of resource, we introduce Deployable and Subscription to represent the cases where the resource is inside it vs in a place pointed by it.
To deploy or discover resources for hybrid application Deployer are needed. There are many assets developed in community for that, our hybrid application model is integrating with them and to simplify the life of application dev/ops.
The last but not least resource in hybrid application model is PlacementRule, it defines which Deployer(s) the Deployable / Subscription is deploying to.
The 5 resources above are the core of the hybrid application model. Based on them, tools are developed to facilitate.
This specification consists of fllowing sections:
The core section defines the essential resources to describe hybrid environment and the resources in it. All custom resources introduced in this section sit in core.hybridapp.io group.
The tools section defines useful tools to facilitate the usage of hybrid application model. All custom resources introduced in this section sit in tools.hybridapp.io group.
The installation section describes how to deploy this model into a hybrid environment
The integration section defines how this model interacts with those systems managing actual resources.