Safe Haskell	None
Language	Haskell2010

Control.Distributed.Fork.Lambda

Contents

Usage
Options

Description

Provides a Backend using AWS Lambda functions.

In order to do that, roughly:

It creates a deployment archive containing the program binary and a tiny wrapper written in Python and uploads it to the given S3 bucket.
Creates a CloudFormation stack containing the Lambda function and an SQS queue to gather the answers.
It starts polling the SQS queue for any answers.
When executing, it invokes the Lambda function using asynchronous invocation mode and blocks until a message appears in the queue.
On exit, it deletes the CloudFormation stack.

Some warts:

The same binary should run on AWS Lambda. In practice, this means:
- You have to build and use this library on a Linux machine.
- You have to statically link everything. You can use GHC's '-static -optl-static -optl-pthread -fPIC' parameters for that. See examples/examples.cabal#L16 for an example.
On AWS Lambda, more memory you assign to a function, more CPU you get. So it might make your function run faster if you overallocate memory.
When invoked asynchronously, AWS Lambda retries the invocation 2 more times waiting a minute between every retry. This means when something fails, it will take at least a few minutes to until you get an exception.

Synopsis

Usage

withLambdaBackend :: LambdaBackendOptions -> (Backend -> IO a) -> IO a Source #

Provides a Backend using AWS Lambda functions.

Created AWS resources except the uploaded deployment package will be cleaned up when exiting.

Example usage:

{-# LANGUAGE StaticPointers #-}

import Control.Lens
import Control.Distributed.Fork
import Control.Distributed.Fork.Lambda

opts :: LambdaBackendOptions
opts = lambdaBackendOptions "my-s3-bucket"
         & lboMemory .~ 1024

main :: IO ()
main = do
  initDistributedFork
  withLambdaBackend opts $ \backend -> do
    handle <- fork backend (static Dict) (static (return "Hello from Lambda!"))
    await handle >>= putStrLn

Options

data LambdaBackendOptions Source #

Options required for creating a Lambda backend.

Use lambdaBackendOptions smart constructor to create and lenses below for setting optional fields.

lambdaBackendOptions Source #

Arguments

:: Text	Name of the S3 bucket to store the deployment archive in.
-> LambdaBackendOptions

lboPrefix :: Lens' LambdaBackendOptions Text Source #

Prefix to the deployment archive and the CloudFormation stack.

Default: "distributed-fork"

lboMemory :: Lens' LambdaBackendOptions Int Source #

Desired memory for the Lambda functions.

See CloudFormation's AWS::Lambda::Function::MemorySize page for allowed values.

Default: 128