如何为CloudWatch仪表盘添加带告警注释的图表部件并解决校验错误

• CloudWatch 图形部件（GraphWidget）不支持仅配置告警注释，必须至少绑定一个指标作为数据源，服务端校验要求部件必须包含metrics或insightRule属性，你的代码只传了告警注释，没有指定指标，因此触发校验失败。
• cdk synth仅做本地语法和类型校验，不会校验云服务端的业务规则，所以本地合成可以正常通过，只有部署到AWS时才会报错。

第一步：修改MetricAlarm类，暴露内部创建的指标对象 #

import {
  Alarm, DimensionHash, Metric, Statistic, Unit,
} from '@aws-cdk/aws-cloudwatch';
import { Construct } from '@aws-cdk/core';

export class MetricAlarm {
  public readonly alarm: Alarm;
  // 新增：暴露指标对象供仪表盘部件使用
  public readonly metric: Metric;

  constructor(scope: Construct, id: string, {
    namespace,
    metricName,
    label,
    dimensions,
    statistic = Statistic.AVERAGE,
    threshold,
    alarmName,
    alarmDescription,
    unit = Unit.COUNT,
    evaluationPeriods = 1,
  }: MetricAlarmProps) {
    this.metric = new Metric({
      namespace,
      metricName,
      label,
      dimensions,
      statistic,
      unit,
    });
    this.alarm = this.metric.createAlarm(scope, id, {
      evaluationPeriods,
      threshold,
      alarmName,
      alarmDescription,
    });
  }
}

第二步：修改AlarmMetricWidget类，增加指标入参并绑定到部件 #

import { GraphWidget, IMetric } from '@aws-cdk/aws-cloudwatch';

// AlarmMetricWidgetProps 定义新增metric字段
export default class AlarmMetricWidget extends GraphWidget {
  constructor({
    alarmAnnotation,
    title,
    size = 'standard',
    metric // 新增：指标参数
  }: AlarmMetricWidgetProps) {
    super({
      title,
      leftAnnotations: [alarmAnnotation],
      // 绑定指标到部件，满足服务端校验要求
      leftMetrics: [metric],
      width: (size === 'wide' ? 12 : 6),
    });
  }
}

第三步：修改调用代码，传入指标参数 #

// 此处已预先定义好dashboard对象
const ecsServiceAlarm = new ECSServiceAlarm(scope, id, {
  namespace: 'AWS/ECS',
  metricName: 'CPUUtilization',
  statistic: Statistic.AVERAGE,
  dimensions: {
    ClusterName: ecsClusterName,
    ServiceName: ecsServiceName,
  },
  label,
  threshold,
  alarmName,
  alarmDescription,
});
const widget = new AlarmMetricWidget({
  alarmAnnotation: ecsServiceAlarm.alarm.toAnnotation(),
  // 传入指标
  metric: ecsServiceAlarm.metric,
  title: 'My alarm widget',
});
dashboard.addWidgets(widget);

修改后重新部署即可正常通过校验，部件会同时展示指标趋势和告警阈值线，符合使用预期。

内容的提问来源于stack exchange，提问作者phuwin