custom-database-controller
Example respository for the blog post Kubernetes Custom Resources Grow Up in v1.10.
This repository implements a simple custom database controller which scales mysql deployments as per the Database custom resources.
This follows the same pattern as that of the Kuberentes sample-controller.
Installation
export GOPATH=~/go
go get github.com/nikhita/custom-database-controller
Prerequisites
Custom Resources support /status and /scale subresources as an
alpha feature in v1.10. You will need a Kubernetes cluster with version of at least 1.10.
Enable this feature using the CustomResourceSubresources feature gate on the kube-apiserver for v1.10.
This feature is enabled by default for versions >v1.10.
--feature-gates=CustomResourceSubresources=trueRunning
# assumes you have a working kubeconfig, not required if operating in-cluster
$ go run *.go -kubeconfig=$HOME/.kube/config
# create a CustomResourceDefinition
$ kubectl create -f artifacts/databases-crd.yaml
# create a custom resource of type Database
$ kubectl create -f artifacts/mysql-database.yaml
# check deployments created through the Databse custom resource
$ kubectl get deploymentsYou can scale the Database custom resource, which can automatically scale the mysql deployments as well.
$ kubectl get deployments
NAME DESIRED CURRENT UP-TO-DATE AVAILABLE AGE
my-user 1 1 1 1 4s
# scaling
$ kubectl scale --replicas=3 databases/mysql
database.example.com "mysql" scaled
# after scaling
$ kubectl get deployments
NAME DESIRED CURRENT UP-TO-DATE AVAILABLE AGE
my-user 3 3 3 3 1m