Specify Array of VPC SubnetID / SecurityGroupIds to aws cli cloudformation deploy - amazon-web-services

Question

I am using aws-cli to deploy my stack across several environments and need to parametrize the subnets / security groups available to my stack.
I have a section in my SAM template defining the subnets and security groups as such:
EnvSubnets:
Description: Define subnet ids
Type: 'List<AWS::EC2::Subnet::Id>'
EnvSecGroups:
Description: Security Groups
Type: 'List<AWS::EC2::SecurityGroup::Id>'
I specify the arguments using `aws cloudformation deploy ... --parameter-overrides file://env.json' but cannot find a single format that passes the arrays to cloudformation.
I keep getting the followign errors:
#/VpcConfig/SecurityGroupIds: expected type: JSONArray, found: String #/VpcConfig/SubnetIds: expected type: JSONArray, found: String
Any hints?

Answer 1

It seems that at the current time this is not supported - I ended-up using a nested template driven by a user-overridable parameter:
AWSTemplateFormatVersion: '2010-09-09'
Transform: AWS::Serverless-2016-10-31
Description: 'SAM Template for XXXXX XXXXX'
Parameters:
LambdaRole:
Description: Define exiting Lambda role to provide permissions
Type: String
LambdaImage:
Description: Define Lambda image URI
Type: String
LambdaVPCInclude:
Description: S3 URI of the YAML for the S3 VPC section
Type: String
Resources:
FOO:
Type: AWS::Serverless::Function
Properties:
PackageType: Image
ImageUri: !Ref LambdaImage
Architectures:
- x86_64
MemorySize: 1024
Timeout: 900
Role: !Ref LambdaRole
'Fn::Transform':
Name: 'AWS::Include'
Parameters:
Location: !Ref LambdaVPCInclude
Metadata:
SamResourceId: FOO
Outputs:
QuantUniverse:
Description: FOO Lambda Function ARN
Value: !GetAtt FOO.Arn
and in an S3 bucket I have a file with my VPC config:
VpcConfig:
SubnetIds:
- subnet-*****************
- subnet-*****************
- subnet-*****************
SecurityGroupIds:
- sg-*****************
- sg-*****************
and pass the S3 URI of this file as the override for LambdaVPCInclude in aws cloudformation deploy
Hope this helps others.