Passing Security Group Ids and Subnet Ids in a Clould Formation template-CodePudding

Parameters:
  ClusterName:
    Type: String
  ClusterVersion:
    Type: Number
    AllowedValues: [1.21, 1.20, 1.19, 1.18]
  RoleArnValue:
    Type: String
  ListOfSubnetIDs: 
    Description: Array of Subnet IDs
    Type: List<AWS::EC2::Subnet::Id>
  ListOfSecurityGroupIDs:
    Description: Array of security group ids
    Type: List<AWS::EC2::SecurityGroup::Id>


Resources:
  EKSCluster:
    Type: AWS::EKS::Cluster
    Properties:
      Name: !Sub ${ClusterName}
      Version: !Sub ${ClusterVersion}
      RoleArn: !Sub ${RoleArnValue}
      ResourcesVpcConfig:
        SecurityGroupIds: 
          - !Sub ${ListOfSecurityGroupIDs}
        SubnetIds:
          - !Sub ${ListOfSubnetIDs}

Above is the .yaml clouldformation template I have created so i can spin up eks cluster. Then i am using aws cli to spin up the cluster using the following command.

aws cloudformation deploy --template-file eks.yaml --stack-name cluster-test --parameter-overrides ClusterName=Dev ClusterVersion=1.21 ListOfSubnetIDs=subnet-11111d11b11b011f4,subnet-99999d237f87f11d7,subnet-222222c110c7e4be7,subnet-88888884de8d25176  ListOfSecurityGroupIDs=sg-01111111a21221 RoleArnValue=arn:aws:iam::123456546456:role/cluster-ServiceRole-WMIC72AOWSP0 --capabilities CAPABILITY_NAMED_IAM

I get the following error

An error occurred (ValidationError) when calling the CreateChangeSet operation: Template error: variable ListOfSecurityGroupIDs in Fn::Sub expression does not resolve to a string

I am not sure why. Am i using !sub in correctly? Would really appreciate input on this.

CodePudding user response：

Since you want to reference the parameters you provided the template as they are, you should use the Ref function.

Here's an example of a valid template:

Parameters:
  ClusterName:
    Type: String
  RoleArnValue:
    Type: String
  ListOfSubnetIDs: 
    Description: Array of Subnet IDs
    Type: List<AWS::EC2::Subnet::Id>
  ListOfSecurityGroupIDs:
    Description: Array of security group ids
    Type: List<AWS::EC2::SecurityGroup::Id>


Resources:
  EKSCluster:
    Type: AWS::EKS::Cluster
    Properties:
      Name: !Ref ClusterName
      RoleArn: !Ref RoleArnValue
      ResourcesVpcConfig:
        SecurityGroupIds: !Ref ListOfSecurityGroupIDs
        SubnetIds: !Ref ListOfSubnetIDs

and here's how I deployed it:

aws cloudformation deploy --template-file eks.yml --stack-name cluster-test --parameter-overrides ClusterName=Dev ListOfSubnetIDs=subnet-be0a99c4,subnet-c71046ae ListOfSecurityGroupIDs=sg-009690ac6b3bff6df,sg-009a3f1cb63943941 -RoleArnValue=...

Sub should be used when you want to perform string manipulation. Checkout the examples from the documentation.