❗ NOTICE: Python users using Schedule class in aws_events, aws_applicationautoscaling, aws_autoscaling, aws_backup, get synth-time "TypeError: ...got aws_cdk._ScheduleProxy instead" in CDK 2.97.0

[russbiggs]

Please add your +1 👍 to let us know you have encountered this

Status: IN-PROGRESS

Overview:

In CDK 2.97.0, we released #27105: "feat(core): Schedule class". This broke python users of the 4 stable modules that were updated:

• aws_events
• aws_applicationautoscaling
• aws_autoscaling
• aws_backup

As well as two experimental modules:

• aws_scheduler_alpha
• aws_synthetics_alpha

When passing in a schedule to any of the above modules in python, cron, expression, rate, at all return aws_cdk._ScheduleProxy type instead of the module specific schedule type.

This was allowed because TypeScript does structural typing and we were relying on this to cast core.Schedule as module.Schedule. jsii did not throw an error for this kind of type casting so it was allowed into v2.97.0.

Complete Error Message:

TypeError: type of argument schedule must be one of (aws_cdk.aws_events.Schedule, NoneType); got
aws_cdk._ScheduleProxy instead

Workaround:

Downgrade to CDK v2.96.2
Upgrade to 2.97.1 or later

Solution:

We will revert the offending PR first. There will be a following PR to reimplement this and another PR in jsii to ensure that structural typing is caught by jsii errors.

Related Issues:

---

Original bug report reproduced here:

Describe the bug

When creating a aws_events Rule creation fails when passing aws_cdk.aws_events.Schedule. The cron, expression, rate methods all seem to return a aws_cdk._ScheduleProxy type not the documented and required aws_cdk.Schedule type:

TypeError: type of argument schedule must be one of (aws_cdk.aws_events.Schedule, NoneType); got aws_cdk._ScheduleProxy instead

Expected Behavior

calling aws_events.Schedule methods should return a aws_events.Schedule type as documented in the CDK docs and in type annotation.

Current Behavior

aws_events.Schedule method return a aws_cdk._ScheduleProxy type. When attempting to use the Schedule constructor for a Schedule type as in the example in the docs:

https://docs.aws.amazon.com/cdk/api/v2/python/aws_cdk.aws_events/Rule.html:

schedule (Optional[Schedule]) – The schedule or rate (frequency) that determines when EventBridge runs the rule. You must specify this property, the eventPattern property, or both. For more information, see Schedule Expression Syntax for Rules in the Amazon EventBridge User Guide. Default: - None.

e.g.

rule = events.Rule(self, "Rule",
    schedule=events.Schedule.rate(cdk.Duration.hours(1))
)

This fails with the following error:

TypeError: type of argument schedule must be one of (aws_cdk.aws_events.Schedule, NoneType); got aws_cdk._ScheduleProxy instead

Reproduction Steps

Using the documented example will reproduce the error:

rule = events.Rule(self, "Rule",
    schedule=events.Schedule.rate(cdk.Duration.hours(1))
)

using events.Schedule.expression(...) and events.Schedule.cron(...) produce the same problem.

Outside of a CDK application checking the return type in plain Python also shows that the method incorrectly return a _ScheduleProxy object

from aws_cdk import aws_events

print(type(aws_events.Schedule.rate(Duration.hours(1))))

# returns <class 'aws_cdk._ScheduleProxy'>

Possible Solution

No response

Additional Information/Context

using aws-cdk-lib==2.97.0 in python 3.11.4

The type annotation in the source documents the intended return type as Schedule as well

e.g.:

    @jsii.member(jsii_name="cron")
    @builtins.classmethod
    def cron(
        cls,
        *,
        day: typing.Optional[builtins.str] = None,
        hour: typing.Optional[builtins.str] = None,
        minute: typing.Optional[builtins.str] = None,
        month: typing.Optional[builtins.str] = None,
        week_day: typing.Optional[builtins.str] = None,
        year: typing.Optional[builtins.str] = None,
    ) -> "Schedule":

CDK CLI Version

2.97.0

Framework Version

No response

Node.js Version

v18.15.0

OS

Mac OS 13.1 (22C65)

Language

Python

Language Version

3.11.4

Other information

No response

[danielwilton-metoffice]

I believe this is because the new core.Schedule functionality is actually returning a core.LiteralSchedule that extends the core.Schedule class, which has protected members and isn't the matching consumer aws_events.Schedule with public members, causing issues when compiled with JSII.

[russbiggs]

Can confirm this is a new issue in 2.97.0 with the changes around core.Schedule. downgrading to 2.96.0 resolves the issue.

[fucksmile]

Can confirm this is a new issue in 2.97.0 with the changes around core.Schedule. downgrading to 2.96.0 resolves the issue.

Hello,
New issue when downgrading:
This CDK CLI is not compatible with the CDK library used by your application. Please upgrade the CLI to the latest version.
(Cloud assembly schema version mismatch: Maximum schema version supported is 32.0.0, but found 34.0.0)

[russbiggs]

Can confirm this is a new issue in 2.97.0 with the changes around core.Schedule. downgrading to 2.96.0 resolves the issue.

Hello, New issue when downgrading: This CDK CLI is not compatible with the CDK library used by your application. Please upgrade the CLI to the latest version. (Cloud assembly schema version mismatch: Maximum schema version supported is 32.0.0, but found 34.0.0)

This isnt an issue with CDK instead an issue with your environment. When downgrading you need to update your CLI version to match the correct schema, as indicated in the error message you posted.

[fucksmile]

as indicated in the error message you posted.

downgrading to 2.96.0 resolves the issues/27259
upgrade the CLI to the latest version just as issues/27259:TypeError: type of argument schedule must be one of (aws_cdk.aws_events.Schedule, NoneType); got aws_cdk._ScheduleProxy instead.
Sorry, my problem is I don't know how to downgrade CDK library to match CDK CLI 2.96.0
Any help?

[danielwilton-metoffice]

as indicated in the error message you posted.

downgrading to 2.96.0 resolves the issues/27259 upgrade the CLI to the latest version just as issues/27259:TypeError: type of argument schedule must be one of (aws_cdk.aws_events.Schedule, NoneType); got aws_cdk._ScheduleProxy instead. Sorry, my problem is I don't know how to downgrade CDK library to match CDK CLI 2.96.0 Any help?

This is an issue with the CDK version you are using with your application. Not the CDK CLI version.

[fucksmile]

This is an issue with the CDK version you are using with your application. Not the CDK CLI version.

Sorry, my problem is I don't know how to downgrade CDK library to match CDK CLI 2.96.0 Any help?
Where is CDK library, How to install CDK library? This is the first time I have used CDK
I installed CDK CLI 2.96.0 run with npm install -g [email protected]
I ran with python3 -m pip install aws-cdk-lib==2.96.0 not work

[russbiggs]

This is an issue with the CDK version you are using with your application. Not the CDK CLI version.

Sorry, my problem is I don't know how to downgrade CDK library to match CDK CLI 2.96.0 Any help?

Where is CDK library, How to install CDK library? This is the first time I have used CDK

I installed CDK CLI 2.96.0 run with npm install -g [email protected]

I ran with python3 -m pip install aws-cdk-lib==2.96.0 not work

This isn't really the right forum for support on how to use CDK and the CDK CLI since this is a bug report. I recommend checking out the CDK docs https://docs.aws.amazon.com/cdk/v2/guide/getting_started.html for a guide on how to use CDK.

[pwrmiller]

As a note, this also impacts applicationautoscaling.Schedule; ([email protected], cdk 2.94.0)

        if isinstance(resp, _OkayResponse):
            return self._serializer.structure(resp.ok, response_type)
        elif isinstance(resp, _CallbackResponse):
            return resp.callback
        else:
            if resp.name == ErrorType.JSII_FAULT.value:
                raise JSIIError(resp.error) from JavaScriptError(resp.stack)
>           raise RuntimeError(resp.error) from JavaScriptError(resp.stack)
E           RuntimeError: type of argument schedule must be aws_cdk.aws_applicationautoscaling.Schedule; got aws_cdk._ScheduleProxy instead

Of course, downgrading to CDK 2.96.2 works around the issue for now. In pyproject.toml, one can use:

aws-cdk-lib = "2.96.2"

[riskersen]

Possible workaround, pinning cdk lib version in requirements.txt to 2.96.0

aws-cdk-lib==2.96.0

[danielwilton-metoffice]

As a note, this also impacts applicationautoscaling.Schedule; ([email protected], cdk 2.94.0)

        if isinstance(resp, _OkayResponse):
            return self._serializer.structure(resp.ok, response_type)
        elif isinstance(resp, _CallbackResponse):
            return resp.callback
        else:
            if resp.name == ErrorType.JSII_FAULT.value:
                raise JSIIError(resp.error) from JavaScriptError(resp.stack)
>           raise RuntimeError(resp.error) from JavaScriptError(resp.stack)
E           RuntimeError: type of argument schedule must be aws_cdk.aws_applicationautoscaling.Schedule; got aws_cdk._ScheduleProxy instead

Yeah, this is due to the refactor that moved all Schedule functionality to core.Schedule.

Linked issue:
#27258

[peterwoodworth]

We're working on it, thanks for the reports 👍🏻

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