amazon web services - Using an EventBridge event pattern string in a lambda function

Question

I have a lambda function using Python. It's connected to an EventBridge rule that triggers every time there's a change in a Glue table.

The event pattern it's outputting looks something like this:

{
    "version":"0",
    "detail":{
        "databaseName":"flights-db",
        "typeOfChange":"UpdateTable",
        "tableName":"flightscsv"
    }
}

I want to get the tableName and databaseName values from this output into the function as a variable.

My Lambda function:

import json
import boto3

def lambda_handler(event, context):
    boto3_version = boto3.__version__

    return_statement = 'Boto3 version: ', boto3_version,
                       'Event output: ', event

    return {
        'statusCode': 200,
        'body': json.dumps(return_statement)
    }

I was expecting to get the event pattern output from the event in my return statement but that's not the case.

When testing this function the return output for event is:

{"key1": "value1", "key2": "value2", "key3": "value3"}

This key and values are defined like this in the Test Pattern for the function.

The eventbridge rule is defined like this:

How can I get the values from the event pattern to a variable? Do I need to configure the test pattern to get the results into event?

EDIT: Picture of log events for the table change event:

question from:https://stackoverflow.com/questions/66064163/using-an-eventbridge-event-pattern-string-in-a-lambda-function

Answer 1

The event object generated by CloudWatch (CW) Events / Event Bridge (EB) are listed here. These events will be passed to your function when it is going to get triggered by EB.

Your EB Event Pattern should be:

{
  "source": ["aws.glue"],
  "detail-type": ["Glue Data Catalog Table State Change"]
}

The above should match changes to any tables in your glue catalog. The event should be similar to the one below:

{
    "version": "0",
    "id": "2617428d-715f-edef-70b8-d210da0317a0",
    "detail-type": "Glue Data Catalog Table State Change",
    "source": "aws.glue",
    "account": "123456789012",
    "time": "2019-01-16T18:16:01Z",
    "region": "eu-west-1",
    "resources": [
        "arn:aws:glue:eu-west-1:123456789012:table/d1/t1"
    ],
    "detail": {
        "databaseName": "d1",
        "changedPartitions": [
            "[C.pdf, dir3]",
            "[D.doc, dir4]"
        ],
        "typeOfChange": "BatchCreatePartition",
        "tableName": "t1"
    }
}

Thus, to get tableName and databaseName your lambda function could be:

import json
import boto3

def lambda_handler(event, context):
    boto3_version = boto3.__version__

    print(event)

    table_name = event['detail']['tableName']
    database_name = event['detail']['databaseName']

    print(table_name, database_name)

    return_statement = {
        'boto3_version': boto3_version,
        'table_name': table_name,
        'database_name': database_name
    }

    return {
        'statusCode': 200,
        'body': json.dumps(return_statement)
    }

For testing, you can setup sample EB event in your lambda test window: