CAST AI Hello World Skill

CAST AI Hello World

Overview

First API calls against the CAST AI REST API: list connected clusters, retrieve the savings report, and inspect node inventory. All examples use curl with the X-API-Key header -- no SDK required.

Prerequisites

Completed castai-install-auth setup
CASTAI_API_KEY environment variable set
At least one cluster connected to CAST AI

Instructions

Step 1: List Connected Clusters

curl -s -H "X-API-Key: ${CASTAI_API_KEY}" \
  https://api.cast.ai/v1/kubernetes/external-clusters \
  | jq '.items[] | {id, name, status, providerType}'

Expected output:

{
  "id": "abc123-def456",
  "name": "production-eks",
  "status": "ready",
  "providerType": "eks"
}

Step 2: Get Cluster Savings Report

export CASTAI_CLUSTER_ID="your-cluster-id"

# Current month savings
curl -s -H "X-API-Key: ${CASTAI_API_KEY}" \
  "https://api.cast.ai/v1/kubernetes/clusters/${CASTAI_CLUSTER_ID}/savings" \
  | jq '{
    monthlySavings: .monthlySavings,
    savingsPercentage: .savingsPercentage,
    currentCost: .currentMonthlyCost,
    optimizedCost: .optimizedMonthlyCost
  }'

Step 3: List Cluster Nodes

curl -s -H "X-API-Key: ${CASTAI_API_KEY}" \
  "https://api.cast.ai/v1/kubernetes/external-clusters/${CASTAI_CLUSTER_ID}/nodes" \
  | jq '.items[] | {
    name: .name,
    instanceType: .instanceType,
    lifecycle: .lifecycle,
    cpu: .allocatableCpu,
    memory: .allocatableMemory,
    zone: .zone
  }'

Step 4: Check Autoscaler Policies

curl -s -H "X-API-Key: ${CASTAI_API_KEY}" \
  "https://api.cast.ai/v1/kubernetes/clusters/${CASTAI_CLUSTER_ID}/policies" \
  | jq '{
    enabled: .enabled,
    unschedulablePods: .unschedulablePods.enabled,
    nodeDownscaler: .nodeDownscaler.enabled,
    spotInstances: .spotInstances.enabled
  }'

Output

List of connected clusters with IDs and status
Monthly savings report with before/after cost
Node inventory with instance types and lifecycle (spot vs on-demand)
Autoscaler policy status

Error Handling

| Error | Cause | Solution | |-------|-------|----------| | 401 Unauthorized | Bad API key | Regenerate at console.cast.ai | | 404 Not Found | Wrong cluster ID | List clusters first to get correct ID | | Empty items array | No clusters connected | Run castai-install-auth to onboard | | agentStatus: offline | Agent not running | Check kubectl get pods -n castai-agent |

Resources

Next Steps

Proceed to castai-local-dev-loop to set up a development workflow.

Agent Skills: CAST AI Hello World

Install this agent skill to your local

Skill Files