/**
* Health Check Handler (SMELL-001 God Object Refactor)
*
* Handles GET /health endpoint - System health check (NEW).
*
* Responsibilities:
* - Check MCP client pool status
* - Check schema cache status
* - Calculate uptime
* - Return JSON health response
*
* Complexity: LOW (50 lines, 3 dependencies, new endpoint)
*
* WHY new endpoint?
* - Standard practice: Health checks for container orchestration (Kubernetes, Docker)
* - Monitoring: Liveness/readiness probes
* - Debugging: Quick status overview without parsing metrics
*
* @see https://github.com/aberemia24/code-executor-MCP/issues/42
*/
import type { IncomingMessage, ServerResponse } from 'http';
import type { IRequestHandler, HandlerDependencies } from './request-handler.interface.js';
import type { SchemaCache } from '../../validation/schema-cache.js';
/**
* Health check response structure
*/
export interface HealthCheckResponse {
/** Overall health status */
healthy: boolean;
/** ISO 8601 timestamp */
timestamp: string;
/** Server uptime in milliseconds */
uptime: number;
/** MCP client pool status */
mcpClients: {
/** Number of connected MCP servers */
connected: number;
};
/** Schema cache status */
schemaCache: {
/** Number of cached schemas */
size: number;
};
}
/**
* Handles GET /health - Health Check Endpoint (NEW)
*
* Returns JSON status information for monitoring and debugging.
* Useful for:
* - Kubernetes liveness/readiness probes
* - Docker health checks
* - Load balancer health checks
* - Quick debugging (is server running? are MCP clients connected?)
*/
export class HealthCheckHandler implements IRequestHandler {
private startTime = Date.now();
/**
* Create health check handler
*
* @param options - Handler dependencies (mcpClientPool, metricsExporter, schemaCache)
*/
constructor(
private options: HandlerDependencies & { schemaCache: SchemaCache }
) {}
/**
* Handle GET /health request
*
* @param req - HTTP request
* @param res - HTTP response
* @param authToken - Pre-validated auth token (for audit logging)
*/
async handle(
_req: IncomingMessage,
res: ServerResponse,
_authToken: string
): Promise<void> {
// Gather health information
const tools = this.options.mcpClientPool.listAllTools();
const cacheStats = this.options.schemaCache.getStats();
// Build response
const response: HealthCheckResponse = {
healthy: tools.length > 0,
timestamp: new Date().toISOString(),
uptime: Date.now() - this.startTime,
mcpClients: {
connected: tools.length,
},
schemaCache: {
size: cacheStats.size,
},
};
// Return JSON response (always 200, even if unhealthy)
// Load balancers check response body for health status
res.writeHead(200, { 'Content-Type': 'application/json' });
res.end(JSON.stringify(response));
}
}
