CSI-Addons for Kubernetes

This repository contains the implementation for the CSI-Addons specification that can be used with Kubernetes.

The CSI API is tightly integrated with Kubernetes. In order to extend the interface, a new CSI-Addons Controller is needed. The CSI-Addons Controller will watch for Kubernetes events (CRs) and relay operation initiated by the user to the CSI-driver.

.------.   CR  .------------.
| User |-------| CSI-Addons |
'------'       | Controller |
               '------------'
                      |
                      | gRPC
                      |
            .---------+------------------------------.
            |         |                              |
            |  .------------.        .------------.  |
            |  | CSI-Addons |  gRPC  |    CSI     |  |
            |  |  side-car  |--------| Controller |  |
            |  '------------'        | NodePlugin |  |
            |                        '------------'  |
            | CSI-driver Pod                         |
            '----------------------------------------'

A CSI-Addons side-car will be running in the CSI-driver (provisioner and node-plugin) Pods. The side-car calls gRPC procedures for CSI-Addons operations.

CSI-driver side-car

The CSI-driver side-car is located with the CSI-Controller (provisioner) and the CSI-nodeplugin containers. The side-car registers itself by creating a CSIAddonsNode CR that the CSI-Addons Controller can use to connect to the side-car and execute operations.

Controller

The CSI-Addons Controller handles the requests from users to initiate an operation. Users create a CR that the controller inspects, and forwards a request to one or more CSI-Addons side-cars for execution.

By listing the CSIAddonsNode CRs, the CSI-Addons Controller knows how to connect to the side-cars. By checking the supported capabilities of the side-cars, it can decide where to execute operations that the user requested.