Mocking the service-side of AWS Lambda runtime (useful to test you own runtime implementations)

lambda-runtime-mock.hs

module Main (main) where

import           Control.Concurrent     (newChan, readChan, writeChan)
import           Control.Monad.IO.Class (liftIO)
import           Data.Text              (Text)
import           Web.Scotty


main :: IO ()
main = do
  ch <- newChan

  scotty 3000 $ do
    post "/2018-06-01/runtime/invocation/next" $ do
      payload <- body
      liftIO $ writeChan ch payload

    get "/2018-06-01/runtime/invocation/next" $ do
      addHeader "Lambda-Runtime-Aws-Request-Id" "8476a536-e9f4-11e8-9739-2dfe598c3fcd"
      addHeader "Lambda-Runtime-Deadline-Ms" "1542409706888"
      addHeader "Lambda-Runtime-Invoked-Function-Arn" "arn:aws:lambda:us-east-2:123456789012:function:custom-runtime"
      addHeader "Lambda-Runtime-Trace-Id" "Root=1-5bef4de7-ad49b0e87f6ef6c87fc2e700;Parent=9a9197af755a6419;Sampled=1"
      setHeader "Content-Type" "application/json"
      payload <- liftIO $ readChan ch
      raw payload

    post "/2018-06-01/runtime/invocation/:awsRequestId/response" $ do
      awsRequestId <- param "awsRequestId" :: ActionM Text
      liftIO $ print $ "Received response for " <> awsRequestId

    post "/2018-06-01/runtime/invocation/:awsRequestId/error" $ do
      awsRequestId <- param "awsRequestId" :: ActionM Text
      liftIO $ print $ "Received error for " <> awsRequestId

    post "/2018-06-01/runtime/init/error" $ do
      payload <- body
      liftIO $ print $ "Received initialization error for " <> payload