This README is the one indexed from the repository at its latest ref, not from the tag for this version.

Warning

This project is still in very early development stages, but should be complete enough to use in production. that being said, use this at your own risk.

MineTrain

A lightweight and easy to use shard for running crystal in AWS Lambda

MineTrain was heavily influenced by the following projects:

• https://github.com/spinscale/crystal-aws-lambda
• https://github.com/lambci/crambda

Installation

Add MineTrain to your crystal functions shards.yml file

dependencies:
  mine_train:
    github: SteffanPerry/MineTrain
    version: 0.0.2

Usage

Create a method that optionally accepts the mine train event and context types:

require "mine_train"

class CustomClass
  def self.perform(event : MineTrain::Lambda::Event, context : MineTrain::Lambda::Context)
    # Do work...
  end
end

In your entry file, require mine_train and pass a block to the mine_train_run method:

require "mine_train"
require "./custom_class.cr"

mine_train_run do |event, context|
  CustomClass.perform(event, context)
end

You can use use event values within the mine_train_run block to dynamically call specific jobs based on input. Additionally, methods do not need to accept event or context arguments if they are not required.

# custom_class.cr
require "mine_train"

class CustomClass
  def self.perform(event : MineTrain::Lambda::Event, context : MineTrain::Lambda::Context)
    # Do work...
  end

  def self.perform_two(event : MineTrain::Lambda::Event)
    # Do work...
  end

  def self.perform_three
    # Do work...
  end
end

# main.cr
require "mine_train"
require "./custom_class.cr"

mine_train_run do |event, context|
  case event.body["value"]
  when "perform"
    CustomClass.perform(event, context)
  when "perform_two"
    CustomClass.perform_two(event)
  when "perform_three"
    CustomClass.perform_three
  end
end

Building and deployment

Taken from another project, use docker to build the bootstrap and upload the zipped file to your aws lambda function:

Build the application

docker run --rm -it -v $PWD:/app -w /app crystallang/crystal:latest \
  crystal build src/main.cr -o lib/mine_train/bootstrap/bootstrap \
    --release --static --no-debug

Zip the deployable bootstrap

zip -j bootstrap.zip lib/mine_train/bootstrap/bootstrap

MineTrain::Lambda::Event

The MineTrain::Lambda::Event type has two public methods:

body

this is the JSON parsed value of the raw event.body

raw

This is the raw event request from the lambda invocation

MineTrain::Lambda::Context

The MineTrain::Lambda::Context type has the following public methods:

function_name

The name of the lambda function

function_version

The version of the lambda function

memory_limit_in_mb

The configured memory for the lambda function

log_group_name

The lambda functions log group

log_stream_name

The log stream for the lambda function

aws_request_id

The unique AWS request ID

invoked_function_arn

The ARN of the invoked function

deadline_ms

The remaining time in mills to complete the lambda function

identity (optional)

The cognito invocation identity

client_context (optional)

The client context of the lambda function

get_remaining_time_in_millis

Method which returns the remaining time to complete the function