Unable to set ScheduleExpression to at(some date) and delete rule after completion

[mgsotelo]

Describe the bug

Hi,

I am encountering an issue with the boto3 library where I am unable to set the ScheduleExpression to at(some date) using the put_rule method for CloudWatch Events. Additionally, I am unable to delete the rule after it has been triggered because the library does not accept the at ScheduleExpression.

Please let me know if there is a workaround for this issue or if there are any plans to support the at(some date) ScheduleExpression in the future.

Thank you!

Regression Issue

• Select this option if this issue appears to be a regression.

Expected Behavior

The put_rule method should accept the at(some date) ScheduleExpression and create the rule successfully.

Current Behavior

The put_rule method throws a ValidationException indicating that the ScheduleExpression is not valid.

Reproduction Steps

1. Attempt to create a CloudWatch Events rule with a ScheduleExpression set to at(some date) using the put_rule method.
2. Observe that the ScheduleExpression is not accepted and results in a ValidationException.

Code Example:

import boto3
from datetime import datetime, timedelta, timezone

# Initialize boto3 client, it may need credentials or something
events_client = boto3.client('events')

# Calculate the event launch time (1 hour from now) => the event should be sent to a lambda function (yay!) 
expected_time = datetime.now(timezone.utc) + timedelta(hours=1)
schedule_expression = f"at({expected_time.isoformat()})"

# Attempt to create the rule
try:
    response = events_client.put_rule(
        Name='awesome-event-instance-rule',
        ScheduleExpression=schedule_expression,
        State='ENABLED',
        Description='Do something awesome at a specific time'
    )
    print("Rule created:", response)
except Exception as e:
    print("Error creating rule:", str(e))

Possible Solution

IDK

Additional Information/Context

I also need to delete the rule after it has been triggered, but since the at ScheduleExpression is not accepted, I am unable to achieve this.

SDK version used

boto3==1.36.10

Environment details (OS name and version, etc.)

Python 3.11.5 // macOS Sonoma 14.2.1