Preamble

The introduction of Custom Runtimes has opened up new possibilities when it comes to the spectrum of languages that can be used in Amazon Lambda. This short document will show how to run virtually any statically linked binary on it. The example will cover a stack built Haskell project.

Preparations

Create an Amazon Linux instance compatible with Lambda, you can use AMI link provided on the page (this is the one current for the time when this document was written, but make sure you have a look at the page if something goes not the way you expected).
- In theory it should be also possible to install Amazon Linux locally
SSH to the instance as you would usually do
Upgrade pip and aws-cli on the instance
sudo pip install --upgrade pip
sudo /usr/local/bin/pip install --upgrade awscli
Create an IAM user for lambda operations with AWSLambdaFullAccess policy attached
- Enable programmatic access and export appropriate env vars:
```
export AWS_ACCESS_KEY_ID=..
export AWS_SECRET_ACCESS_KEY=..
export AWS_DEFAULT_REGION=..
```
Create IAM role called basic-execution-role with AWSLambdaBasicExecutionRole policy attached to it
- note down role arn

Install `bootstrap` file as a new lambda layer

Save this file to file named bootstrap

#!/bin/sh

set -euo pipefail

while true
do
 HEADERS="$(mktemp)"

 # Pass the event straight to binary
 RESPONSE=$(curl -sS -LD "$HEADERS" -X GET "http://${AWS_LAMBDA_RUNTIME_API}/2018-06-01/runtime/invocation/next" | ./${_HANDLER})
 REQUEST_ID=$(grep -Fi Lambda-Runtime-Aws-Request-Id "$HEADERS" | tr -d '[:space:]' | cut -d: -f2)

 # Send the response
 curl -X POST "http://${AWS_LAMBDA_RUNTIME_API}/2018-06-01/runtime/invocation/$REQUEST_ID/response"  -d "$RESPONSE"
done

zip bootstrap.zip boostrap
aws lambda public-layer-version --layer-name binary-layer --zip-file fileb://bootstrap.zip
note down the LayerVersionArn

Create lambda binary

Create Haskell binary to run on the instance
- Install stack
  - curl -sSL https://get.haskellstack.org/ | sh
  - Install required software
    - sudo yum install perl make automake gcc gmp-devel libffi zlib xz tar git gnupg
- Create a simple project
  - stack new lambda
  - cd lambda
  - stack build
  - stack exec lambda-exe (to make sure it build and works properly)
Package the binary
- cd .stack-work/install/x86_64-linux/lts-12.20/8.4.4/bin/ && zip ~/lambda.zip lambda-exe && cd - (beware of lts directory which may vary)

Upload lambda code

cd ~ && aws lambda create-function --function-name my-lambda --layers <layer_version_arn_from_above> --handler lambda --runtime provided --role <execution_role_arn> --zip-file fileb://lambda.zip

Test the lambda

aws lambda invoke --function-name my-lambda response.txt
if everything goes well you should see success - make sure by looking into output file response.txt

kubek2k/simple-binary-lambda-tutorial.md