Advanced StatefulSet

This is an Advanced StatefulSet CRD implementation based on official StatefulSet in Kubernetes 1.16.0.

This is an experimental project.

Features

In addition to official StatefulSet, it adds one feature:

• Scale in at an arbitrary position: kubernetes/kubernetes#83224

Test it out

start a cluster

curl -Lo ./kind https://github.com/kubernetes-sigs/kind/releases/download/v0.6.1/kind-$(uname)-amd64
chmod +x ./kind
./kind create cluster --image kindest/node:v1.16.3 --config hack/kindconfig.v1.16.3.yaml --name advanced-statefulset
export KUBECONFIG=$(kind get kubeconfig-path --name advanced-statefulset)

install CRD

kubectl apply -f deployment/crd.v1.yaml

run advanced statefulset controller locally

Open a new terminal and run controller:

hack/local-up.sh

deploy a statefulset

kubectl apply -f examples/statefulset.yaml

scale out

Note that --resource-version is required for CRD objects.

RESOURCE_VERSION=$(kubectl get statefulsets.pingcap.com web -ojsonpath='{.metadata.resourceVersion}')
kubectl scale --resource-version=$RESOURCE_VERSION --replicas=4 statefulsets.pingcap.com web

scale in

RESOURCE_VERSION=$(kubectl get statefulsets.pingcap.com web -ojsonpath='{.metadata.resourceVersion}')
kubectl scale --resource-version=$RESOURCE_VERSION --replicas=3 statefulsets.pingcap.com web

scale in at arbitrary position

We should set delete-slots annotations and decrement spec.replicas at the same time.

kubectl apply -f examples/scale-in-statefulset.yaml