CODEWITHSUNDEEP
arraysamazon-web-servicessplitparametersmapping
xoon
xoon

Reputation: 11

AWS Cloudformation Parameters Allowed Values

I am creating a stack in AWS Cloudformation to build an EC2 Instance. Therefore I need certain parameters that the user should enter. My task is to choose between different types. Based on these types, the corresponding values are to be displayed in another list.

I thought I could solve this problem with the following code (Mappings included):

"Parameters": {
    "ProjectName": {
        "Description": "Enter the project name.",
        "Type": "String"
    },
    "InstanceType": {
        "Description": "Select your Instance type.",
        "AllowedValues": [
            "t3",
            "m5",
            "r5"
        ],
        "Default": "t3",
        "Type": "String"
    },
    "InstanceTypeSize": {
        "Description": "Select your Instance type size.",
        "AllowedValues":{
            "Fn::Split" : [
                ",",
                    { "Fn::FindInMap": [
                        "Params",
                        {"Ref": "InstanceType"},
                        "values"
                    ]}
                ]
            },
        "Type": "String"
    }
},
"Mappings": {
    "Params": {
        "t3": {
            "values": "t3.nano,t3.micro,t3.small,t3.medium,t3.large,t3.xlarge,t3.2xlarge"
        },
        "m5": {
            "values": "m5.large,m5.xlarge,m5.2xlarge,m5.4xlarge,m5.8xlarge,m5.12xlarge,m5.16xlarge,m5.24xlarge,m5.metal"
        },
        "r5": {
            "values": "r5.large,r5.xlarge,r5.2xlarge,r5.4xlarge,r5.8xlarge,r5.12xlarge,r5.16xlarge,r5.24xlarge,r5.metal"
        }
    }
}

The Split method returns a list of strings. The parameter "AllowedValues" needs "an array containing the list of values allowed for the parameter".

Does anyone have any idea what I am doing wrong or where the error is? Is there possibly an alternative solution for the problem?

Upvotes: 1

Views: 3503

Answers (1)

samtoddler
samtoddler

Reputation: 9625

Intrinsic Function Ref can't be used inside the Parameters

                 { "Fn::FindInMap": [
                        "Params",
                        {"Ref": "InstanceType"},
                        "values"
                    ]}

You have to define the instance types as one big array

"Parameters": {
    "ProjectName": {
        "Description": "Enter the project name.",
        "Type": "String"
    },
    "InstanceType": {
        "Description": "Select your Instance type.",
        "AllowedValues": [t3.nano,t3.micro,t3.small,t3.medium,t3.large,t3.xlarge,t3.2xlarge,m5.large,m5.xlarge,m5.2xlarge,m5.4xlarge,m5.8xlarge,m5.12xlarge,m5.16xlarge,m5.24xlarge,m5.metal,r5.large,r5.xlarge,r5.2xlarge,r5.4xlarge,r5.8xlarge,r5.12xlarge,r5.16xlarge,r5.24xlarge,r5.metal
        ],
        "Default": "t3",
        "Type": "String"
    },
    "InstanceTypeSize": {
        "Description": "Select your Instance type size.",
        "AllowedValues":{ 
            "Fn::Split" : [
                ",", 
                    { "Fn::FindInMap": [
                        "Params",
                        {"Ref": "InstanceType"},
                        "values"
                    ]}
                ]
            },
        "Type": "String"
    }
}

Upvotes: 2

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