vpa_butler

A Kubernetes controller designed to simplify the process of deploying and managing VerticalPodAutoscalers (VPAs) for deployments, statefulsets, and daemonsets. This controller automatically creates instances of the VerticalPodAutoscaler CRD as payload is created in your cluster, saving developers time and effort.

Motivation

Deploying VPA instances is a necessary step to enable automatic scaling for workloads in Kubernetes. However, the process of manually deploying VPA instances can be tedious and time-consuming. vpa_butler automates this process by creating VerticalPodAutoscalers with reasonable defaults while respecting custom VPA instances.

Functionality

vpa_butler is a Kubernetes controller that continuously watches all deployments, statefulsets, and daemonsets within your cluster. When it encounters a resource not currently being targeted by a VPA instance, it creates a new VPA resource with appropriate defaults.

The served VPA is constructed in the following way:

• The VPA is created in the same namespace as the targeted resource and named like the targeted resource adding the suffix -deployment, -statefulset, -daemonset.
• The update mode is set to the value of the --default-vpa-update-mode CLI flag.
• The minAllowed recommendation is set to the values of the --default-min-allowed-cpu and --default-min-allowed-memory CLI flags.
• The maxAllowed recommendation is set to the percentage of capacity specified by the --capacity-percent CLI flag of the largest viable node regarding memory. The vpa_butler determines the viable nodes by considering, where pods of the payload could be scheduled on respecting NodeName, NodeAffinity, NodeUnscheduable and TaintToleration.

Every 30 seconds the maxAllowed values are updated. This feature ensures that pods stay schedulable. To opt-out of the vpa_butler, deploy a custom VPA instance along with the payload. The vpa_butler will clean-up the VPA instances it served.

The served VPA can be adjusted using the following annotations on the payload resource (do not annotate the pod template):

• vpa-butler.cloud.sap/main-container can be set to the name of the most resource-hungry container of eventually created pods. That container will have the maxAllowed recommendations increased.
• vpa-butler.cloud.sap/update-mode sets the update mode on the served VPA.
• vpa-butler.cloud.sap/controlled-values sets the controlled values on the served VPA.