CloudFormation创建CloudWatch Dashboard时DashboardBody报错及Ref参数无效问题

错误原因 #

你遇到的报错由三个核心问题导致：

• YAML模板基础语法错误：Parameters节点下所有参数的子属性（Default、Description等）未正确缩进，属于不合法的YAML结构
• CloudFormation内置函数作用范围问题：Ref写在硬编码的字符串内部时，CloudFormation不会识别执行，只会将其当作普通文本处理，无法完成参数替换
• DashboardBody的JSON结构本身非法：字符串内部引号未正确转义，末尾多了多余的闭合括号，导致JSON解析失败

修正方案 #

使用CloudFormation的!Sub函数配合YAML多行文本块构造DashboardBody，不需要手动转义引号，同时可以自动完成参数变量替换。
修正后的完整模板如下：

AWSTemplateFormatVersion: 2010-09-09
Description: "AWS CloudFormation Sample Template for Cloudwatch alert and Dashboard configuration."
Parameters: 
  AlarmNameForCPU: 
    Default: Service_CpuUtilization
    Description: AlarmName
    MaxLength: "99"
    MinLength: "1"
    Type: String
  AlarmNameForMemory: 
    Default: Service_MemoryUtilization
    Description: AlarmName
    MaxLength: "99"
    MinLength: "1"
    Type: String
  DashboardName: 
    Default: ServiceDashboard
    Description: Dashboard
    MaxLength: "99"
    MinLength: "1"
    Type: String
  DashboardTitleCPU: 
    Default: CpuUtilization
    Description: DashboardTitle
    MaxLength: "99"
    MinLength: "1"
    Type: String
  DashboardTitleMemory: 
    Default: MemoryUtilization
    Description: DashboardTitle
    MaxLength: "99"
    MinLength: "1"
    Type: String
Resources:
  Dashboard:
    Type: "AWS::CloudWatch::Dashboard"
    Properties:
      DashboardName: !Ref DashboardName
      DashboardBody: !Sub |
        {
          "widgets": [
            {
              "height": 3,
              "width": 9,
              "y": 0,
              "x": 0,
              "type": "metric",
              "properties": {
                "title": "${DashboardTitleCPU}",
                "annotations": {
                  "alarms": [
                    "arn:aws:cloudwatch:us-east-1:468491150671:alarm:${AlarmNameForCPU}"
                  ]
                },
                "view": "singleValue"
              }
            },
            {
              "height": 3,
              "width": 9,
              "y": 0,
              "x": 9,
              "type": "metric",
              "properties": {
                "title": "${DashboardTitleMemory}",
                "annotations": {
                  "alarms": [
                    "arn:aws:cloudwatch:us-east-1:468491150671:alarm:${AlarmNameForMemory}"
                  ]
                },
                "view": "singleValue"
              }
            }
          ]
        }

如果你的账号ID或者区域不是固定值，也可以用AWS::AccountId、AWS::Region伪参数替换硬编码的468491150671和us-east-1，实现模板跨账号跨区域复用。

内容的提问来源于stack exchange，提问作者Santosh