how to pass reference to existing VPC to a cloudformation template?

Question

I am creating a cloudformation template, with few resources, couple of lambda functions , S3 bucket.see code below, it is work on progress and so far I have a S3 bucket and a lamda function triggered by S3. we have vpc defined in our team that we are supposed to use. I would like to add private subnet under that vpc for my lambda function and assign public subnet for the s3 bucket. how to get reference of the vpc , and pass it to my template and use it? sample code will be helpful.

AWSTemplateFormatVersion: 2010-09-09
Resources:

  # S3 Bucket
  S3Bucket:
    Type: AWS::S3::Bucket

  # Functions
  S3-Lambda-trigger:
    Type: AWS::Serverless::Function
    Properties:
      CodeUri: .
      Handler: lambda.handler
      Description: s3 object creation triggers lambda
      Runtime: nodejs12.x
      Events:
        S3Bucket:
          Type: S3
          Properties:
            Bucket: !Ref S3Bucket
            Events: 's3:ObjectCreated:*'

  # Permissions
  Allow-lamda-invocation-s3:
    Type: AWS::Lambda::Permission
    Properties:
      Action: 'lambda:InvokeFunction'
      FunctionName: !Ref S3-Lambda-trigger
      Principal: s3.amazonaws.com
      SourceArn: !GetAtt S3Bucket.Arn

Marcin Marcin · Accepted Answer · 2020-07-02T02:49:42

how to get reference of the vpc , and pass it to my template and use it?

One way would be through AWS-Specific Parameter Types, specifically AWS::EC2::VPC::Id, in a Parameters section.

For example:

AWSTemplateFormatVersion: 2010-09-09

Parameters: 

  VPCId: 
    Type: AWS::EC2::VPC::Id

Resources:

  MySubnet:
    Type: AWS::EC2::Subnet
    Properties: 
      # other properties
      VpcId: !Ref VPCId

Thanks to this, when creating the stack in AWS Console, you would be able to choose existing VPCId to pass to the template.

how to pass reference to existing VPC to a cloudformation template?

1 Answers