# Lambda Telemetry Extension

Instrumenting AWS Lambda functions with Baselime is straightforward using our Lambda Extension. The Lambda Extension listens to invocation events and collects telemetry data, such as logs and runtime metrics. Once collected, the telemetry data is sent to Baselime for storage, analysis, and visualization. In this section, we'll walk you through the process of instrumenting your Lambda functions with the Baselime Lambda Extension.

Before getting started you'll need to make sure that you have your Baselime API key ready. You can get it by running the following command using the Baselime CLI.

baselime iam

# How it works

The Baselime Lambda Extension is language agnostic and is compressed as a single binary, such that it minimises its impact cold-starts and performance.

The diagram below illustrates how the Baselime Lambda Extension works within your architecture.

Using the Baselime Lambda Extension
Using the Baselime Lambda Extension

All the telemetry data from your Lambda function is collected asynchronously from your invocation, and sent to the Baselime backend in a separate process from your invocation.

# Instrumenting

To instrument your AWS Lambda Functions with the Baselime Lambda Extension, we recommend using your Infrastructure as Code tool of choice, and add the Extension as a Lambda Layer.

It is necessary to add the Baselime API key to the extension as an environment variable. The example below shows the process with the Serverless Framework.

# serverless.yml
service: myService
  name: aws
  runtime: python3.8
    handler: handler.hello

Where the BASELIME_KEY is your Baselime API Key and the BASELIME_LAMBDA_LAYER_ARN is the ARN of the Baselime Layer in your region.

`arn:aws:lambda:${region}:097948374213:layer:baselime-extension-${'x86_64' || 'arm64'}:1`