This page is meant as a template for writing a CIP. To create a CIP choose Tools->Copy on this page and modify with your content and replace the heading with the next CIP number and a description of your issue. Replace anything in italics with your own description.

Status

Current state: Under Discussion

...

To make it easy to run Cassandra on Kubernetes. If an operator is like a robot in your datacenter running your Cassandra cluster, what does that operator need: a) To make informed decisions. b) Exposed from node to cluster to take actions

Audience

• Devops
• Developers
• Ops

Goals

Operator Maturity Scale

(Taken from https://github.com/operator-framework/operator-sdk)

• Lower the impedance between Kubernetes and Cassandra operations
• Achieve Level 3 Operator compliance, plus Horizontal Scaling from Level 5.
• Provide pathway to Level4
• Listed on https://operatorhub.io/

What does Level 1, 2 and 3 look like in the Cassandra world?

E.g.

• L1: How do we support all the configuration options etc?
• L2: Patch management and pausing broken upgrades / running mixed versions etc.

Level 1 operator for Apache Cassandra

Level 2 operator for Apache Cassandra

Level 3 operator for Apache Cassandra

Non-Goals

• Remove the need for any Cassandra administration. (Not Level 5)
  
• Provide a serverless facade for Cassandra
• Official Docker images??

Proposed Changes

A new repository as a sub-project for Apache Cassandra specifically for a Kubernetes Operator

New or Changed Public Interfaces

Briefly list any new interfaces that will be introduced as part of this proposal or any existing interfaces that will be removed or changed. The purpose of this section is to concisely call out the public contract that will come along with this feature.

...

• pluggable components (SPIs) like authorisation, triggers, ..? - Better support for K8s service discovery mechanisms
• configuration - Probably something related to k8s service discovery e.g. a k8s seed provider maybe? 
• The operator will define a Kubernetes Custom Resource (CRD), this will be the primary API for interacting with the operator.

...

• Target version: 3.x and above
• What impact (if any) will there be on existing users? None
• The operator will need to support minor and major version upgrades of Apache Cassandra

Test Plan

• Used as a part of CI/CD for Apache Cassandra project
  • dtest
  • harry
  • fallout
• TBD - Acceptance framework for k9s Operators. (Need guidance on that criteria)

Rejected Alternatives

• HELM charts

...