(aws-cloudfront): Unexpected diffs caused by cloudfront.Function

Non deterministic auto-generated function name causing unexpected diffs.

Reproduction Steps

Using this code:

new cloudfront.Function(stack, 'Function', {
  code: cloudfront.FunctionCode.fromInline('function handler(event) { return event.request }'),
});

1. synth and extract the function name
2. synth again and extract the function name

The function name is different for every synth.

What did you expect to happen?

The function name should be the same.

What actually happened?

Function name changes per synth.

Environment

• CDK CLI Version : ALL
• Framework Version: 1.109.0
• Node.js Version: ALL
• OS : ALL
• Language (Version): ALL

Other

This happens because of:

https://github.com/aws/aws-cdk/blob/94f81c441f9e2cb8dc70eb2e772d2cd75e468b67/packages/%40aws-cdk/aws-cloudfront/lib/function.ts#L178-L185

Where Stack.of(this).region is an unresolved token that can have a different sequence number every time the program is executed.

A workaround right now would be to provide a name explicitly and not rely on this logic.

Workaround

Provide an explicit name for cloudfront.Function. Using this.node.addr or Node.of(this).addr will return a stable fixed length unique id. Example:

const functionId = `MyFunction${this.node.addr}`;

new cloudfront.Function(stack, functionId, {
  code: cloudfront.FunctionCode.fromInline('function handler(event) { return event.request }'),
  functionName: functionId
});

---

This is 🐛 Bug Report

[eladb]

@madeline-k I don’t believe I would tag it as p2 as basically the entire cloudfront.Function feature is broken in this situation. I would tag it as a p1.

Also, please add the workaround to the issue description so people don’t have to search for it.

Here is what we did in construct-hub (source).

[SachinShekhar]

Any update on this? Sometimes my deployment succeeds; sometimes it doesn’t.