Building Lambda functions with Ruby - Amazon Lambda
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Building Lambda functions with Ruby

You can run Ruby code in Amazon Lambda. Lambda provides runtimes for Ruby that run your code to process events. Your code runs in an environment that includes the Amazon SDK for Ruby, with credentials from an Amazon Identity and Access Management (IAM) role that you manage.

Lambda supports the following Ruby runtimes.

Name Identifier SDK Operating system Architectures Deprecation (Phase 1)

Ruby 3.2



Amazon Linux 2

x86_64, arm64

Ruby 2.7



Amazon Linux 2

x86_64, arm64

Dec 7, 2023

To create a Ruby function
  1. Open the Lambda console.

  2. Choose Create function.

  3. Configure the following settings:

    • Function name: Enter a name for the function.

    • Runtime: Choose Ruby 3.2.

  4. Choose Create function.

  5. To configure a test event, choose Test.

  6. For Event name, enter test.

  7. Choose Save changes.

  8. To invoke the function, choose Test.

The console creates a Lambda function with a single source file named lambda_function.rb. You can edit this file and add more files in the built-in code editor. To save your changes, choose Save. Then, to run your code, choose Test.


The Lambda console uses Amazon Cloud9 to provide an integrated development environment in the browser. You can also use Amazon Cloud9 to develop Lambda functions in your own environment. For more information, see Working with Amazon Lambda functions using the Amazon Toolkit in the Amazon Cloud9 user guide.

The lambda_function.rb file exports a function named lambda_handler that takes an event object and a context object. This is the handler function that Lambda calls when the function is invoked. The Ruby function runtime gets invocation events from Lambda and passes them to the handler. In the function configuration, the handler value is lambda_function.lambda_handler.

When you save your function code, the Lambda console creates a .zip file archive deployment package. When you develop your function code outside of the console (using an IDE) you need to create a deployment package to upload your code to the Lambda function.


To get started with application development in your local environment, deploy one of the sample applications available in this guide's GitHub repository.

Sample Lambda applications in Ruby
  • blank-ruby – A Ruby function that shows the use of logging, environment variables, Amazon X-Ray tracing, layers, unit tests and the Amazon SDK.

  • Ruby Code Samples for Amazon Lambda – Code samples written in Ruby that demonstrate how to interact with Amazon Lambda.

The function runtime passes a context object to the handler, in addition to the invocation event. The context object contains additional information about the invocation, the function, and the execution environment. More information is available from environment variables.

Your Lambda function comes with a CloudWatch Logs log group. The function runtime sends details about each invocation to CloudWatch Logs. It relays any logs that your function outputs during invocation. If your function returns an error, Lambda formats the error and returns it to the invoker.

Enabling Yet Another Ruby JIT (YJIT)

The Ruby 3.2 runtime supports YJIT, a lightweight, minimalistic Ruby JIT compiler. YJIT provides significantly higher performance, but also uses more memory than the Ruby interpreter. YJIT is recommended for Ruby on Rails workloads.

YJIT is not enabled by default. To enable YJIT for a Ruby 3.2 function, set the RUBY_YJIT_ENABLE environment variable to 1. To confirm that YJIT is enabled, print the result of the RubyVM::YJIT.enabled? method.

Example — Confirm that YJIT is enabled
puts(RubyVM::YJIT.enabled?()) # => true