CAST AI Components Hosted On Customers' Clusters

Connecting existing cluster procedure installs several CAST AI components into a cluster.
This is done in phases to provide different levels of experience:

Phase 1 - is meant to provide visibility around connected clusters without possibility of tuning it; one can think of Phase 1 as about operating in read-only mode.
Phase 2 - enables all the functionality of CAST AI platform mostly around clusters optimisation; CAST AI platform instructs clusters and Cloud Providers to re-arrange used resources to reach most optimal state.

Phase 1 Component - CAST AI Kubernetes Agent

CAST AI Agent is the first component installed when a new cluster is connected.
The agent runs as a Pod in a CAST AI dedicated namespace:

» kubectl get pods -n castai-agent
NAME                            READY   STATUS    RESTARTS   AGE
castai-agent-5559cfb4b6-92rkm   2/2     Running   0          21h

There is are two containers running inside that Pod:

CAST AI Kubernetes Agent is responsible for sending cluster state data (snapshots) to the main system
Cluster Proportional Vertical Autoscaler is responsible for tuning allocated resource for this Pod (self-tuning) based on predefined formula

Phase 2 Components - Cluster Controller, Evictor, Spot Handler, AKS Init Data

CAST AI Cluster Controller, Evictor and Spot Handler (installed as DaemonSet, not as a regular Deployment) components are installed when a connected cluster is promoted to Phase 2, which enables cost savings by managing customer's cluster:

» kubectl get deployments -n castai-agent
NAME                        READY   UP-TO-DATE   AVAILABLE   AGE
castai-agent                1/1     1            1           43h
castai-cluster-controller   2/2     2            2           64m
castai-evictor              0/0     0            0           64m

Cluster controller is responsible for executing actions it receives from the central platform (like for example accept a newly created node to the cluster, etc.)
Evictor is responsible for removing pods from underutilised nodes to be able to decrease overall amount of cluster nodes
Spot Handler is responsible for scheduled events monitoring (provided by Instance Metadata Service) and delivering them to the central platform
aks-init-data is responsible for gathering and sending necessary data for AKS node creation. The data contains files from /var/lib/waagent and /var/lib/waagent/ovf-env.xml from the host. Whole process of reading data can be found here. The DaemonSet is a part of cluster-controller helm chart.

Phase 2 Security Components - Kvisor

kvisor is resposible for images vulnerability scanning, Kubernetes YAML manifests linting and CIS security recommendations.