Testing lambda instrumentation with lambda layer

lambda_test.md

Lambda Instrumentation and Layer Test Environment Setup

This guide outlines detailed steps for setting up a test environment to evaluate both Lambda instrumentation (PR) and the Lambda layer (PR) for OpenTelemetry.

Step 1: Creating the Lambda Layer

1. Clone the repository using the ruby-layer-wrapper branch from this location. This branch contains the wrapper file absent in the original PR.
2. Navigate to ruby/src/ and execute sam build -u -t template.yml. This action generates the .aws-sam folder. Finally, run the script ./zip_ruby_layer.sh -n <your_layer_name> to create the zip file suitable for upload to AWS Lambda via the AWS console.
3. If using a different tracing platform, ensure its installation before creating the layers.
4. The gems listed in ruby/layer/Gemfile are the ones to be installed and uploaded.
5. For custom OpenTelemetry initialization (e.g., requiring other vendor-modified agents), edit the ruby/src/wrapper.rb file accordingly.

Step 2: Uploading the Zip File to Create a Layer

Refer to: AWS Lambda Packaging Guide

1. Create a new layer and upload the previously generated zip file.
2. Associate this layer with a function by attaching it to the function configuration.

Step 3: Initializing a Traced Application with OpenTelemetry and Calling the Lambda Function

Assuming the lambda function is triggered (learn more about invoking functions) with the AWS_LAMBDA_URL and AWS_LAMBDA_KEY set:

Example of these two environment variables AWS_LAMBDA_URL=https://abcdefg.execute-api.location-1.amazonaws.com/default/your_lambda_function_name AWS_LAMBDA_KEY=0yN7bRPfu9g***********************0yvXsO7bRtpfu

Example Sinatra app code:

get '/call-with-lambda-aws' do
  url = URI.parse(ENV['AWS_LAMBDA_URL'])
  req = Net::HTTP::Get.new(url.to_s)
  req['x-api-key'] = "#{ENV['AWS_LAMBDA_KEY']}"

  http = Net::HTTP.new(url.host, url.port)
  http.use_ssl = (url.scheme == 'https')

  res = http.request(req)

  content_type :json
  { :Output => "lambda: #{res.body}\n"}.to_json
end

Step 4: Checking the Trace Information

Upon execution, expect to observe a single span with the span scope name as OpenTelemetry::Instrumentation::AwsLambda, accompanied by comprehensive details.