---
name: castai-hello-world
description: |
  Query CAST AI cluster savings report and node inventory.
  Use when verifying CAST AI connectivity, viewing cluster cost savings,
  or listing managed nodes after onboarding.
  Trigger with phrases like "cast ai hello world", "cast ai savings",
  "cast ai cluster status", "test cast ai connection".
allowed-tools: Read, Write, Edit, Bash(curl:*), Bash(kubectl:*)
version: 1.0.0
license: MIT
author: Jeremy Longshore <jeremy@intentsolutions.io>
tags: [saas, kubernetes, cost-optimization, castai]
compatible-with: claude-code
---

# 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

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

### Step 2: Get Cluster Savings Report

```bash
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

```bash
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

```bash
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](https://api.cast.ai/v1/spec/openapi.json)
- [CAST AI Console](https://console.cast.ai)
- [Savings Report Docs](https://docs.cast.ai/docs/getting-started)

## Next Steps

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