CloudWatch Lambda Subscription Filter (CDK-Demo)

Filtering AWS CloudWatch logs and forwarding to AWS Lambda.

In this article, I want to show you how we can use the AWS CloudWatch subscription filter for filtering logs and forward them to a lambda function.

Simple Usecase

Filter critical app errors and send a real-time notification to a Slack channel with error information.

Note that I use AWS CDK for creating the infrastructure.

Create a CloudWatch Log Group

We need to set up a CloudWatch log group for receiving log events from applications. After that, you need to configure your application to send logs to this log group.

Create a Lambda Function for Processing Logs

In this step, we create a Lambda function for processing application logs that come from the CloudWatch subscription filter.

Lambda handler function

Following is the hander function that parses the log events and posts them to a slack channel. Here, you can customize your log events as per your requirement.

Slack URL

You need to create an “Incoming Webhook” in Slack to receive messages from the Lambda function. Refer to this link for instructions.

Create CloudWatch Subscription Filter