Passing values from parent stack to nested stack for Cloudformation - amazon-web-services

Question

I am new to nested stack and i am trying to pass input parameters from parent to child template. My parent stack looks like below:
AWSTemplateFormatVersion: "2010-09-09"
Transform: 'AWS::Serverless-2016-10-31'
Description: "ParentStack with all child stack"
Parameters:
AccountName:
Description: Please Enter valid Account Name.
Type: "CommaDelimitedList"
Default: "citi"
Region:
Description: Enter Region
Type: "CommaDelimitedList"
Default: "us-east-2"
S3BucketName:
Type: "CommaDelimitedList"
Default: ""
S3KeyName:
Type: "CommaDelimitedList"
Default: "Test-LambdaFunction.zip"
Resources:
LambdaStack1:
Type: "AWS::CloudFormation::Stack"
Properties:
Parameters:
TemplateURL: https://test272t3.s3.us-east-2.amazonaws.com/CFTemplates/lambda.yaml
CodeUri:
Bucket: Fn:Join [ ' ', [!Ref S3BucketName] ]
Key: Fn::Join [ ' ', [!Ref S3KeyName] ]
S3Stack:
Type: AWS::CloudFormation::Stack
Properties:
TemplateURL: https://test272t3.s3.us-east-2.amazonaws.com/CFTemplates/s3child.yaml
Parameters:
BucketName: <<not sure how !sub can be paased in parent stack>>
AccessControl: PublicReadWrite
VersioningConfiguration:
Status: Suspended
And part of child template is as follows:
Parameters:
AccountName:
Description: Please Enter valid Account Name.
Type: String
Default: citi
Region:
Description: Enter Region
Type: String
Default: us-east-2
S3BucketName:
Type: "String"
Default: ""
S3KeyName:
Type: "String"
Default: "MeghFlow-DBConnMgmt-Lambda-DBConnMgmtFunction.zip"
testLambda:
Type: AWS::Serverless::Function
Properties:
CodeUri:
Bucket: !Ref S3BucketName
Key: !Ref S3KeyName
Handler: com.testff.testinghand.dbconnmgmt.lambda.testLambda::handleRequest
Runtime: java8
MemorySize: 1024
Policies: AmazonDynamoDBFullAccess
Environment:
Variables:
REGION: us-east-2
DYNAMODB_NAME: DBConnectionInfo
ArtifactBucket:
Type: AWS::S3::Bucket
DeletionPolicy: Delete
Properties:
BucketName: !Sub ${AccountName}-${Region}-artifacts
AccessControl: PublicReadWrite
VersioningConfiguration:
Status: Suspended
Issue: I am not quite sure how the input parameters can be passed from parent to child. I referred few links like but i was confused even more as to when the input type must be CommaDelimitedList vs string. I even tried keeping the param type to string in both parent and child but still i get below error:
"Value of property Parameters must be an object with String (or simple type) properties"
and on using Fn::join get error as below:
"Fn::Join object requires two parameters, (1) a string delimiter and (2) a list of strings to be joined or a function that returns a list of strings (such as Fn::GetAZs) to be joined."
Have referred link : Trying to pass parameters from Master to child template but no luck .
Can anyone guide me in correct direction please. Thanks in advance.

Answer 1

Thanks #gandaliter for your guidance. As per above marked answer CloudFormation parent stack accepts only strings and not any object level parameters(sub parameters under parameters just like CodeURI in my above code). I did few tweaks and changed all the parent template to below :
Note: All the parameter type are set to String in child and parent template
AWSTemplateFormatVersion: "2010-09-09"
Transform: 'AWS::Serverless-2016-10-31'
Description: "ParentStack with all child stack"
Parameters:
apiGatewayStageName:
Type: String
Default: "dev"
HandlerName:
Type: String
Default: "com.test.tehgsaLambda::handleRequest"
S3BucketName:
Type: String
Default: ""
S3KeyName:
Type: String
Default: "Test-LambdaFunction.zip"
Resources:
LambdaStack1:
Type: AWS::CloudFormation::Stack
Properties:
TemplateURL:
Fn::Sub: "https://testyu2y73.s3.us-east-2.amazonaws.com/CFTemplates/lambda.yaml"
Parameters:
S3BucketName: !Ref S3BucketName
S3KeyName: !Ref S3KeyName
HandlerName: !Ref HandlerName
apiGatewayStageName: !Ref apiGatewayStageName
```

Answer 2

I imagine the code you've given above isn't the only combination you've tried, and the parameters don't exactly line up between your parent and child stack, but in any case, the problem is that you're trying to give parameter values of:
CodeUri:
Bucket: Fn:Join [ ' ', [!Ref S3BucketName] ]
Key: Fn::Join [ ' ', [!Ref S3KeyName] ]
and
VersioningConfiguration:
Status: Suspended
Both of these are objects, not 'String (or simple type) properties'. The error is saying that the whole Parameters object must have only simple values.
Incidentally, TemplateURL needs to go outside the Parameters object.