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

• CAST AI API Reference
• CAST AI Console
• Savings Report Docs

Next Steps

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