feat(data_classes): Add CloudWatchAlarmEvent data class

[par6n]

Issue number: #3848

Summary

AWS has recently introduced AWS Lambda as an alarm state change action (link to the news entry). This pull request facilitates reading the event that a CloudWatch Alarm sends to a Lambda function.

Changes

Please provide a summary of what's being changed

• Introduces a new data class: CloudWatchAlarmEvent, along with its satellite data classes and enums.

Pending items:

• Test the class against complex alarms, for example, the ones with mathematical expressions.

User experience

Please share what the user experience looks like before and after this change

You will be able to deserialize the CloudWatch Alarm state change event. Docstrings are added for fields.

from aws_lambda_powertools.utilities.data_classes import event_source, CloudWatchAlarmEvent

@event_source(data_class=CloudWatchAlarmEvent)
def lambda_handler(event: CloudWatchAlarmEvent, context):
    if event.state.value.name == 'ALARM':
        print(f"{event.alarm_arn} is on alarm...")

Checklist

If your change doesn't seem to apply, please leave them unchecked.

• Meet tenets criteria
• I have performed a self-review of this change
• Changes have been tested
• Changes are documented
• PR title follows conventional commit semantics

Is this a breaking change?

RFC issue number:

Checklist:

• Migration process documented
• Implement warnings (if it can live side by side)

Acknowledgment

By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the terms of your choice.

Disclaimer: We value your time and bandwidth. As such, any pull requests created on non-triaged issues might not be successful.

[boring-cyborg]

Thanks a lot for your first contribution! Please check out our contributing guidelines and don't hesitate to ask whatever you need.
In the meantime, check out the #python channel on our Powertools for AWS Lambda Discord: Invite link

[par6n]

@rubenfonseca I'm done with the changes. I've tried running make lint-docs, however it exits with code zero, without returning any errors. I suppose that means no linting issues were found?

[leandrodamascena]

Looking at this

[leandrodamascena]

Hello @par6n! Thank you for sending this OR! This is great work.

I made some comments to improve the customer experience and hope we can address them soon and merge this PR!

[par6n]

@leandrodamascena Thanks for the excellent comments! I'm not a Python-savvy, and I've already learned a few things working on this.

[leandrodamascena]

@leandrodamascena Thanks for the excellent comments! I'm not a Python-savvy, and I've already learned a few things working on this.

Ohhh really? No one can say that you haven't written code in Python for a long time, the code is very clean and well documented.

I'm checking the documentation and I see some fields that are missing, for example when you have a composite alarm you have additional fields, for example:

'previousState': {
      'value': 'ALARM',
      'reason': 'arn:aws:cloudwatch:us-east-1:111122223333:alarm:CompositeDemo.FirstChild transitioned to ALARM at Friday 04 August, 2023 12:54:46 UTC',
      'reasonData': '{"triggeringAlarms":[{"arn":"arn:aws:cloudwatch:us-east-1:111122223333:alarm:CompositeDemo.FirstChild","state":{"value":"ALARM","timestamp":"2023-08-04T12:54:46.138+0000"}}]}',
      'timestamp': '2023-08-04T12:54:46.138+0000',
      'actionsSuppressedBy': 'WaitPeriod',
      'actionsSuppressedReason': 'Actions suppressed by WaitPeriod'
    },

It's very late here and I'm wrapping up the day. Please give me until tomorrow to push some commits that address certain issues. I will explain the details of the fixes that I address.

Please let me know if you have any other questions in the meantime.

Thanks again.

[sonarcloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
No data about Coverage
2.9% Duplication on New Code

See analysis details on SonarCloud

[leandrodamascena]

Hello @par6n! I pushed a commit with a fix for a few small things and here is the list of what I changed:

1 - I removed the CloudWatchAlarmStateValue and CloudWatchAlarmActionSuppressor variables. We are only using this once and can add the type annotation directly to the property.
2 - I optimized some "ifs" to make the code cleaner.
3 - Our intention is to allow the client to access the properties following the same structure they have in JSON, therefore, I changed the location of some fields and created two new classes: CloudWatchAlarmMetricStat and CloudWatchAlarmConfiguration.
4 - I modified the test a little to make it more realistic.

Thank you for your outstanding work on this task. Before merging, I'm sending this PR to @rubenfonseca for review. If you have any questions or need clarification, please feel free to reach out to me.

[par6n]

@leandrodamascena I checked out your changes, and it all looks good to me. Excellent work over there! If there's anything I could do further for this PR, please let me know!

[rubenfonseca]

Reviewing now

[leandrodamascena]

APPROVED!! @par6n

[boring-cyborg]

Awesome work, congrats on your first merged pull request and thank you for helping improve everyone's experience!