Kubernetes controller that ensures deletion of preemptible nodes in a GKE cluster is spread out to avoid the risk of all getting deleted at the same time after 24 hours
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README.md

estafette-gke-preemptible-killer

This small Kubernetes application loop through a given preemptibles node pool and kill a node before the regular 24h life time of a preemptible VM.

License

Why?

When creating a cluster, all the node are created at the same time and should be deleted after 24h of activity. To prevent large disruption, the estafette-gke-preemptible-killer can be used to kill instances during a random period of time between 12 and 24h. It makes use of the node annotation to store the time to kill value.

How does that work

At a given interval, the application get the list of preemptible nodes and check weither the node should be deleted or not. If the annotation doesn't exist, a time to kill value is added to the node annotation with a random range between 12h and 24h based on the node creation time stamp. When the time to kill time is passed, the Kubernetes node is marked as unschedulable, drained and the instance deleted on GCloud.

Usage

You can either use environment variables or flags to configure the following settings:

Environment variable Flag Default Description
DRAIN_TIMEOUT --drain-timeout 300 Max time in second to wait before deleting a node
INTERVAL --interval (-i) 600 Time in second to wait between each node check
KUBECONFIG --kubeconfig Provide the path to the kube config path, usually located in ~/.kube/config. This argument is only needed if you're running the killer outside of your k8s cluster
METRICS_LISTEN_ADDRESS --metrics-listen-address :9001 The address to listen on for Prometheus metrics requests
METRICS_PATH --metrics-path /metrics The path to listen for Prometheus metrics requests

Deploy with Helm

brew install kubernetes-helm
helm init --history-max 25 --upgrade
helm package chart/estafette-gke-preemptible-killer --version 1.0.35
helm upgrade estafette-gke-preemptible-killer estafette-gke-preemptible-killer-1.0.35.tgz --namespace estafette --install --set rbac.create=true

Deploy without Helm

export NAMESPACE=estafette
export APP_NAME=estafette-gke-preemptible-killer
export TEAM_NAME=tooling
export VERSION=1.0.35
export GO_PIPELINE_LABEL=1.0.35
export DRAIN_TIMEOUT=300
export INTERVAL=600
export CPU_REQUEST=10m
export MEMORY_REQUEST=16Mi
export CPU_LIMIT=50m
export MEMORY_LIMIT=128Mi

# Setup RBAC
curl https://raw.githubusercontent.com/estafette/estafette-gke-preemptible-killer/master/rbac.yaml | envsubst | kubectl apply -n ${NAMESPACE} -f -

# Run application
curl https://raw.githubusercontent.com/estafette/estafette-gke-preemptible-killer/master/kubernetes.yaml | envsubst | kubectl apply -n ${NAMESPACE} -f -

Local development

# proxy master
kubectl proxy

# in another shell
go build && ./estafette-gke-preemptible-killer -i 10

Note: KUBECONFIG=~/.kube/config as environment variable can also be used if you don't want to use the kubectl proxy command.