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AWS: Cloud Formation: is it possible to use multiple "DependsOn"?

Given that I have this sample template:

{
    "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" : {
               ...
            }
        }
    }
}

Is it possible to specify multiple DependsOn in any way? It would be great to have something like:

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

What is the normal way?

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3 answers

Yes,

The DependsOn attribute can take a single line or a list of lines .

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

Syntax:

"DependsOn": [String, ...]

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Yes, DependsOn can accept multiple lines. I gave an example below:

"DependsOn": [ "S3BucketAppElbLogs", "ElbLogAppBucketPolicy" ]

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{
    "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"
                }
            }
        }
    }      
}
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