AWS：Cloud Formation：是否可以使用多个“DependsOn”？答案

【问题标题】：AWS: Cloud Formation: Is it possible to use multiple "DependsOn"?AWS：Cloud Formation：是否可以使用多个“DependsOn”？
【发布时间】：2014-03-26 00:16:17
【问题描述】：

鉴于我有这个示例模板：

{
    "AWSTemplateFormatVersion" : "2010-09-09",
    "Mappings" : {
        "RegionMap" : {
            "us-west-1" : { "AMI" : "ami-655a0a20" },
            ...
        }
    },
    "Resources" : {
        "Ec2Instance" : {
            "Type" : "AWS::EC2::Instance",
            "Properties" : {
                ...
            },
            "DependsOn" : "myDB"
        },
        "myDB" : {
            "Type" : "AWS::RDS::DBInstance",
            "Properties" : {
               ...
            }
        },
        "myDB2" : {
            "Type" : "AWS::RDS::DBInstance",
            "Properties" : {
               ...
            }
        }
    }
}

是否可以以任何方式指定多个 DependsOn？有这样的想法会很棒：

"DependsOn" : ["myDB", "myDB2"]

正常的方式是什么？

【问题讨论】：

标签： json templates amazon-web-services amazon-cloudformation

【解决方案1】：

这个答案首先出现在 Google 中，所以我将介绍如何在 YAML 中执行多个依赖属性，我在 this answer 中找到了这些属性。

AnotherProductionResource:
  Type: AWS::CloudFormation::Stack
   Condition: ISProduction
   DependsOn:
   - AResource
   - MyProductionResource
   Properties:
     [...]

【讨论】：

【解决方案2】：

{
    "Description": "Create a variable number of EC2 instance resources.",
    "Parameters": {
        "InstanceCount": {
            "Description": "Number of EC2 instances (must be between 1 and 5).",
            "Type": "Number",
            "Default": 1,
            "MinValue": 1,
            "MaxValue": 5,
            "ConstraintDescription": "Must be a number between 1 and 5."
        },
        "ImageId": {
            "Description": "Image ID to launch EC2 instances.",
            "Type": "AWS::EC2::Image::Id",
            "Default": "ami-31c9924e"
        },
        "InstanceType": {
            "Description": "Instance type to launch EC2 instances.",
            "Type": "String",
            "Default": "m3.medium",
            "AllowedValues": [
                "m3.medium",
                "m3.large",
                "m3.xlarge",
                "m3.2xlarge"
            ]
        }
    },
    "Conditions": {
        "Launch1" : {"Fn::Equals" : [{"Ref" : "InstanceCount"}, "1"]},
        "Launch2" : {"Fn::Equals" : [{"Ref" : "InstanceCount"}, "2"]}       
    },
    "Resources": {
        "Instance2": {
            "Condition": "Launch2",
            "Type": "AWS::EC2::Instance",
            "Properties": {
                "ImageId": {
                    "Ref": "ImageId"
                },
                "InstanceType": {
                    "Ref": "InstanceType"
                }
            },
            "DependsOn": "Instance1"
        },
        "Instance1": {
            "Condition": "Launch1",
            "Type": "AWS::EC2::Instance",
            "Properties": {
                "ImageId": {
                    "Ref": "ImageId"
                },
                "InstanceType": {
                    "Ref": "InstanceType"
                }
            }
        }
    }      
}

【讨论】：

【解决方案3】：

是的， “DependsOn”可以采用多个字符串。我在下面列出了一个示例：

“DependsOn”：[“S3BucketAppElbLogs”，“ElbLogAppBucketPolicy”]

【讨论】：

【解决方案4】：

是的，

DependsOn 属性可以采用单个字符串或字符串列表。

http://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-attribute-dependson.html

语法：

“取决于”：[字符串，...]

【讨论】：

这有效，在 yml 的情况下 >> DependsOn: ConfigA,ConfigB
@Forhad 在 yaml 中为您提供单个 ConfigA,ConfigB 字符串而不是列表