events.Rule has no way to access the rule name

[jeshan]

Hi,
Looking at the Tokens doc page:
https://docs.aws.amazon.com/cdk/latest/guide/tokens.html?shortFooter=true
It's unclear how we could manipulate a property to be used in another resource.
For example, a cloudwatch events rule returns the ruleArn property.
However, I need the rule name property instead (which is not available in the rule object).

I tried to get the name as a sbustring from the arn in Python syntax like this:

rule = Rule(self, 'rule', targets=[LambdaFunction(fn)], schedule=Schedule.rate(Duration.days(1)))
rule.rule_arn # works
rule.rule_arn[5:10] # not good

The last statement does not work since the arn actually looks something like ${Token[TOKEN.219]} at runtime.
I'm thinking that maybe I should be using Token/Lazy/Produce here but I can't figure it out.

[rix0rrr]

You can use stack.parseArn() to take apart the ARN into components, from which you can get the name.

Would you normally use { Ref: MyRule } in a CloudFormation template? If so, this is actually a missing property on the Rule object.

[jeshan]

parseArn works well for me, thanks.

Would you normally use { Ref: MyRule } in a CloudFormation template

Yes, correct. Here is an example:

With the CDK, we can't just reference the rule object, as it throws the error (invoked through Python):

jsii.errors.JavaScriptError: 
  Error: Resolution error: Resolution error: Trying to resolve() a Construct at /Resources/${Token[production.backup-results.fn-failed-invocations-too-high.Resource.LogicalID.543]}/Properties/dimensions/0/value/node.
  Object creation stack:
    at new Intrinsic (/tmp/jsii-kernel-0K7vPp/node_modules/@aws-cdk/core/lib/private/intrinsic.js:20:44)
    at new PostResolveToken (/tmp/jsii-kernel-0K7vPp/node_modules/@aws-cdk/core/lib/util.js:72:9)

[jeshan]

@rix0rrr what do you think? Should I close this one and open a new one for the missing ref?

[NGL321]

@jeshan This issue should be fine to use to track the fix!

😸