Edu/services/classes/src/shared/observability/metrics.ts

import promClient from 'prom-client';

const registry = new promClient.Registry();
// 修复：在本地 registry 上设置默认标签（原代码误用全局 register）
registry.setDefaultLabels({ service: 'classes' });

registry.registerMetric(
  new promClient.Counter({
    name: 'classes_requests_total',
    help: 'Total number of class requests',
    labelNames: ['method', 'endpoint', 'status'],
  }),
);

registry.registerMetric(
  new promClient.Histogram({
    name: 'classes_request_duration_seconds',
    help: 'Class request duration in seconds',
    labelNames: ['method', 'endpoint'],
    buckets: [0.01, 0.05, 0.1, 0.3, 0.5, 1, 3, 5],
  }),
);

export { registry as metricsRegistry };