AWS Lambda now supports Ruby 2.7

You can now develop your AWS Lambda functions using Ruby 2.7. Start using this runtime today by specifying a runtime parameter value of ruby2.7 when creating or updating Lambda functions.

New Ruby runtime features

Ruby 2.7 is a stable release and brings several new features, including pattern matching, argument forwarding, and numbered arguments.

Pattern matching

Pattern matching, a widely used feature in functional programming languages, is introduced as a new experimental feature. This allows deep matching of structured values, checking the structure and binding the matched parts to local variables.

It can traverse a given object and assign it’s value if it matches a pattern:

require "json"
 
json = <<END
{
  "name": "Alice",
  "age": 30,
  "children": [{ "name": "Bob", "age": 2 }]
}
END
 
case JSON.parse(json, symbolize_names: true)
in {name: "Alice", children: [{name: "Bob", age: age}]}
  p age #=> 2
end

For additional information on pattern matching, see Feature #14912.

Argument forwarding

Prior to Ruby 2.7 the * and ** operators are available for single and keyword arguments. These are used to specify any number of arguments or convert array or hashes to several arguments.

Ruby 2.7 added a new shorthand syntax ... for forwarding all arguments to a method irrespective of type. In the example below, all arguments to foo are forwarded to bar, including keyword and block arguments. It acts similar to calling super without any arguments.

def foo(...)
  bar(...)
end

Numbered arguments

Numbered arguments allow you to reference block arguments solely by their index. They are only valid when referenced inside of a block:

Before:

[1, 2, 3].each { |i| puts i }

After:

[1, 2, 3].each { puts @1 }

This can make short code blocks easier to read and reduce code repetition.

Amazon Linux 2

Ruby 2.7, like (Python 3.8, Node.js 10 and 12, and Java 11) is based on an Amazon Linux 2 execution environment. Amazon Linux 2 provides a secure, stable, and high-performance execution environment to develop and run cloud and enterprise applications.

Next steps

Get started building with Ruby 2.7 today by specifying a runtime parameter value of ruby2.7 when creating your Lambda functions. You can read about the Ruby programming model in the AWS Lambda documentation to learn more about writing functions in Ruby 2.7.

For existing Ruby functions, migrate to the new runtime by making any necessary changes to the code for compatibility with Ruby 2.7, then changing the function’s runtime configuration to ruby2.7.

Enjoy, go build with Ruby!