AWS CDK Events (v1)

Common errors

• ModuleNotFoundError: No module named 'aws_cdk_aws_events'

  cause Incorrect import path. CDK v1 constructs are submodules of `aws_cdk`.
  fix Change `import aws_cdk_aws_events` to `from aws_cdk import aws_events`.

• jsii.errors.JavaScriptError: The CDK app must be synthesized before it can be deployed.

  cause The `cdk.App` object's `synth()` method was not called, or the `cdk.out` directory is missing/stale.
  fix Ensure `app.synth()` is called at the end of your CDK application entry point before attempting `cdk deploy`. Run `rm -rf cdk.out` if you suspect a stale output directory.

• You must use the same minor version of @aws-cdk/core and the construct libraries (e.g. aws-cdk-lib) - found @aws-cdk/core@1.100.0 and @aws-cdk/aws-events@1.204.0

  cause Mismatched versions of core CDK library (`aws-cdk`) and construct libraries (e.g., `aws-cdk-aws-events`). All CDK v1 packages must be at the same major.minor version.
  fix Upgrade all `aws-cdk-*` packages to the same major and minor version. Use `pip install -U aws-cdk aws-cdk-aws-events aws-cdk-aws-lambda` (or other relevant packages) to ensure they are consistent.

Warnings

• breaking AWS CDK v1 is in maintenance mode; new projects should use AWS CDK v2. Migrating from v1 to v2 involves significant breaking changes to package imports and construct APIs.
  Fix: For new projects, install `aws-cdk-lib` and use v2 constructs. For existing v1 projects, consult the AWS CDK v2 migration guide before upgrading. Key changes include unified package imports (e.g., `from aws_cdk import aws_events` becomes `from aws_cdk_lib import aws_events`), removal of some L1 constructs, and updated construct signatures.
• gotcha Forgetting to call `app.synth()` or run `cdk deploy` will result in no CloudFormation template generation or AWS resource deployment.
  Fix: Ensure `app.synth()` is called at the end of your CDK application entry point. After synthesis, use the AWS CDK CLI command `cdk deploy` (and `cdk bootstrap` if this is your first deployment to an environment) to provision resources in your AWS account.
• gotcha When defining EventBridge rules for cross-account or cross-region events, ensure proper permissions are granted and event bus policies are correctly configured. A common mistake is restricting the `Detail` field too broadly, preventing events from matching.
  Fix: Review EventBridge documentation for best practices on event patterns and permissions. Use `aws_events.EventBus.from_event_bus_arn()` for existing buses and ensure `PolicyStatement` is correctly attached to allow `events:PutEvents` from source accounts/regions.

Install

• pip install aws-cdk-aws-events aws-cdk Install library and core CDK

Imports

• aws_events
  wrong:

  import aws_cdk_aws_events

  correct:

  from aws_cdk import aws_events

  CDK v1 construct libraries are imported as submodules of `aws_cdk`, not directly using their PyPI package name.

Quickstart

This quickstart demonstrates how to create an EventBridge rule that triggers a Lambda function every 5 minutes using `aws-cdk-aws-events` within an AWS CDK v1 application. Run `cdk deploy` after `app.synth()` to deploy.

import aws_cdk as cdk
from aws_cdk import aws_events
from aws_cdk import aws_events_targets as targets
from aws_cdk import aws_lambda as lambda_

class MyEventStack(cdk.Stack):
    def __init__(self, scope: cdk.App, id: str, **kwargs) -> None:
        super().__init__(scope, id, **kwargs)

        # Define a simple Lambda function to be a target
        my_lambda = lambda_.Function(
            self, "MyEventHandler",
            runtime=lambda_.Runtime.PYTHON_3_9,
            handler="index.handler",
            code=lambda_.Code.from_inline("import json; def handler(event, context): print(json.dumps(event)); return 'OK'")
        )

        # Create an EventBridge rule that triggers every 5 minutes
        rule = aws_events.Rule(
            self, "MyScheduleRule",
            schedule=aws_events.Schedule.rate(cdk.Duration.minutes(5)),
            description="Rule that triggers every 5 minutes"
        )

        # Add the Lambda function as a target for the rule
        rule.add_target(targets.LambdaFunction(my_lambda))

app = cdk.App()
MyEventStack(app, "MyEventBridgeStack")
app.synth()