aws_lambda_runtime

An AWS Lambda runtime for crystal.

While this is a working implementation, it is not tested yet and the API is likely subject to change. Feel free to give it a try, nonetheless!

Installation

  1. Add the dependency to your shard.yml:

    dependencies:
  aws_lambda_runtime:
    github: lagr/aws_lambda_runtime

  2. Run shards install

Usage

The basic usage which should be suitable for most use cases is as follows:

require "aws_lambda_runtime"

AwsLambdaRuntime.run do |event, invocation|
  # do your thing

  puts "event is a #{event.class.name}."
  # => event is a JSON::Any.

  # return something that responds to to_json
  { "serialize-this": "my friend" }
end

This will provide event as JSON::Any and invocation as AwsLambdaRuntime::Invocation to the block.

Advanced Usage

Passing a Proc, e.g. one derived from a method, permits to bypass the parsing of the event as JSON::Any:

def handler(event, invocation)
  # do your thing

  puts "event is a #{event.class.name}."
  # => event is a JSON::Any.

  # return something that responds to to_json
  { "serialize-this": "my friend" }
end

AwsLambdaRuntime.run(->handler(JSON::Any, AwsLambdaRuntime::Invocation))

Working on the raw String can be handy to define custom mappings for the expected event data or to defer parsing to a later point in time:

class SQSMessage
  include JSON::Serializable

  @[JSON::Field(key: "messageId")]
  property message_id : String

  property attributes : JSON::Any
end

class SQSEvent
  include JSON::Serializable

  @[JSON::Field(key: "Records")]
  property messages : Array(SQSMessage)
end

def handler(event, invocation)
  puts "event is a #{event.class.name}."
  sqs_event = SQSEvent.from_json(event)

  { "first-message-attributes": sqs_event.messages.first.attributes }
end

AwsLambdaRuntime.run(->handler(String, AwsLambdaRuntime::Invocation))

Development

TODO :-)

Notable Mentions

This shard is inspired by crambda.

Contributing

  1. Fork it (https://github.com/lagr/aws_lambda_runtime/fork)
  2. Create your feature branch (git checkout -b my-new-feature)
  3. Commit your changes (git commit -am 'Add some feature')
  4. Push to the branch (git push origin my-new-feature)
  5. Create a new Pull Request

Contributors