Using CloudFormation's Fn::Sub with Bash parameter substitution
Let’s say that you need to inject a large bash script into a CloudFormation AWS::EC2::Instance Resource’s UserData property. CloudFormation makes this easy with the Fn::Base64 intrinsic function: 1 2 3 4 5 6 7 8 9 10 11 12 AWSTemplateFormatVersion: '2010-09-09' Resources: VPNServerInstance: Type: AWS::EC2::Instance Properties: ImageId: ami-efd0428f InstanceType: m3.medium UserData: Fn::Base64: | #!/bin/sh echo "Hello world" In your bash script, you may even want to reference a parameter created elsewhere in the CloudFormation template....