TL;DR: don’t forget about the default cache policy

I was trying to deploy a CloudFront distribution with CloudFormation. I wanted to follow best practices, so I was trying to use a cache policy rather than embedding the cache configuration inline with the ForwardedValues field.

I had my cache behaviours defined:

Resources:
  Distribution:
    Type: AWS::CloudFront::Distribution
    Properties:
      # ...
      CacheBehaviors:
        - CachePolicyId: !Ref CachePolicy

  CachePolicy:
    Type: AWS::CloudFormation::CachePolicy
    Properties:
      # ...

I was deploying and getting the error “The parameter ForwardedValues is required”. I was bashing my head against this, trying to use {} or !Ref AWS::NoValue but that didn’t fix things.

I wanted to follow best practices, and defining a cache policy is more powerful.

Finally my googling uncovered the answer:

…I had forgotten to include the CachePolicyId field in by DefaultCachePolicy!

One more quick thing - as a brit, I slipped up on typing Behaviours (extra “u”) all the time. Thanks to cfn-lint and the CloudFormation tools for helping me catch that early!