CODEWITHSUNDEEP
amazon-web-servicesnestedaws-cloudformation
flyingcars34
flyingcars34

Reputation: 353

AWS cloudformation pass value to nested stack

I'm having trouble creating stacks using nested stacks. I have one master template (the one listed is for testing, and is only reference one nested stack). I am trying to figure out how to pass a value from the master to the nested stack, or is there a better way to do this? Every time try to create the stack, I get a:

Template format error: Unresolved resource dependencies [VpcCidrBlock] in the Resources block of the template.

Which I understand means the parameter I put in the master stack is not getting passed to the nested stack.

Master Template:

{
    "AWSTemplateFormatVersion" : "2010-09-09",
    "Description" : "Master template",
    "Parameters" : {
        "availabilityZone" : {
            "Default" : "us-east-1d",
            "Description" : "Enter AvailabilityZone.",
            "Type" : "String"
        },
        "VpcCidrBlock" : {
            "Default" : "10.0.0.0/16",
            "Description" : "VPC CIDR Block.",
            "Type" : "String"
        }
    },
    "Resources" : {
        "VPCStack" : {
            "Type" : "AWS::CloudFormation::Stack",
            "Properties" : {
                "TemplateURL" : "https://s3.amazonaws.com/dev.url.templates/templates/vpcStack.json",
                "TimeoutInMinutes" : "5",
                "Parameters" : {
                    "VpcCidrBlock" : {
                        "Ref" : "VpcCidrBlock"
                    }
                }
            }
        }
    }
}

VPC Template:

{
    "AWSTemplateFormatVersion" : "2010-09-09",
    "Description" : "VPC template",
    "Resources" : {
        "VpcStack" : {
            "Type" : "AWS::EC2::VPC",
            "Properties" : {
                "EnableDnsSupport" : "true",
                "EnableDnsHostnames" : "true",
                "CidrBlock" : {
                    "Ref" : "VpcCidrBlock"
                },
                "Tags" : [
                    {
                        "Key" : "Application",
                        "Value" : {
                            "Ref" : "AWS::StackName"
                        }
                    }
                ]
            }
        }
    }
}

Thanks!

Upvotes: 0

Views: 1738

Answers (1)

Matt Houser
Matt Houser

Reputation: 36073

Your internal template needs an input parameter:

"Parameters" : {
    "VpcCidrBlock" : {
        "Description" : "VPC CIDR Block.",
        "Type" : "String"
    }
},

Just like your outer "wrapper" template.

Upvotes: 2

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