Cannot use Condition (or condition.ref) in FnOr

[mipearson]

eg:

    HasManagedPolicies:
      !Or [ { Condition: UseManagedPolicyARN }, { Condition: UseECR } ]

or even:

    CreateMetricsStack:
      Condition: UseAutoscaling

It feels like I should be able to do this:

    const useManagedPolicyARN = new cdk.Condition(...);
    const useEcr = new cdk.Condition(...);
    const hasManagedPolicies = new cdk.Condition(this, "HasManagedPolicies", {
      expression: new cdk.FnOr(
        useManagedPolicyARN,
        useEcr
      )
    });

But the cdk.Condition class does not match the type definition of the predicate functions (which require FnCondition.

After some mucking around, I found the following workaround, but it relies on Fn simply re-emitting exactly what it's passed:

    const hasManagedPolicies = new cdk.Condition(this, "HasManagedPolicies", {
      expression: new cdk.FnOr(
        new cdk.Fn("Condition", "UseManagedPolicyARN"),
        new cdk.Fn("Condition", "UseECR")
      )
    });

This applies to referring to Conditions within FnOr and so forth within resources as well.

What is the correct way to express this in CDK?

[rix0rrr]

We've generally avoided Conditions so far, since we prefer expressing conditions in the CDK app.

I'm assuming you're using CDK to generate reusable templates that will be deployed by someone else?

Will look into the code.

[rix0rrr]

I think the idea was to use

 const hasManagedPolicies = new cdk.Condition(this, "HasManagedPolicies", {
      expression: new cdk.FnOr(
        useManagedPolicyARN.ref,
        useEcr.ref
      )
    });

Does that not work?

[mipearson]

Yep, this is me evaluating CDK as "a tool to synthesize templates" rather than "a tool to manage AWS".

We're not big users of conditions anyway, but nice to have coverage.

That example unfortunately doesn't work - ref is a string, and FnOr expects an FnCondition.

[rix0rrr]

Got it. Will file this as a bug then.