wbuchwalter/kubernetes-webhook-autoscaler

An autoscaler that call user-specified webhooks when conditions for scale in/out are detected in a Kubernetes cluster.

Kubernetes-webhook-autoscaler

Kubernetes autoscaler using webhooks.

This works in two pieces :

• The Kubernetes autoscaler part is interacting with the API of the cluster and sending webhooks
• The 'client' part is receiving the hooks and triggering the scaling. You can find example of this part inside the examples folder.

Full List of Options

$ python main.py [options]

Option	Description	Default
--kubeconfig	Path to kubeconfig YAML file. Leave blank if running in Kubernetes to use service account
--scale-out-webhook	URI to be called when a scaling out need is detected by the autoscaler
--scale-in-webhook	URI to be called when a scaling in need is detected by the autoscaler
--pool-name-regex	Regex used to identify agents in the pool(s), the regex should not match masters. kubectl get nodes to find your worker node names	agent
--drain	Wether the autoscaler should drain and cordon nodes before passing them to the scale-in webhook
--sleep	Time (in seconds) to sleep between scaling loops	60
-v	Sets the verbosity. Specify multiple times for more log output, e.g. -vvv
--debug	Do not catch errors. Explicitly crash instead
--ignore-pools	Names of the pools that the autoscaler should ignore, separated by a comma
--spare-agents	Number of agent per pool that should always stay up	1
--idle-threshold	Maximum duration (in seconds) an agent can stay idle before being deleted
--over-provision	Number of extra agents to create when scaling up	0

Payload

Scale In

[
    {
        name: "pool1",
        target_nodes: ["node1", "node2"],
        current_agent_count: 5,
        desired_agent_count: 3
    }
]

Scale Out

[
    {
        name: "pool1",
        current_agent_count: 3,
        desired_agent_count: 5
    }
]

Deploy it in a K8s cluster using Helm

helm install helm-chart --name k8s-wh-as \
    --set options.scaleoutwebhook=<SCALE-OUT-URL>,options.scaleinwebhook=<SCALE-IN-URL>,options.poolnameregex=<REGEX-NODES-TO-WATCH>

Running locally

$ make build-run
#in the container
$ python main.py [arguments]