Example of running .NET executables with AWS Lambda and Mono

README.md

Example of running .NET executables with AWS Lambda and Mono

This is a simple .NET application which does reads from stdin and prints the result backwards. This is compiled with mono and executed with AWS lambda.

Instructions

• Setup
  • boot a new Amazon Linux EC2 instance (t2.micro is fine)
  • Edit /etc/yum.repos.d/epel.repo
  • set enabled=1 in [epel] section
  • run sudo yum install mono-core mono-extras mono-devel
  • run sudo yum groupinstall "Development Tools"
• Build
  • git clone https://gist.github.com/e200ed6699addb6c1052eb0deb41c0f1.git reverse_cat
  • cd reverse_cat
  • make
• Deploy
  • Upload reverse_cat.zip to s3
  • Upload provided cloud template to s3 folder
  • Optional edit make file to point to a bucket your ec2 has access to, run make upload
  • Launch cloudformation template
  • specify the bucket and full key to the uploaded zip file
  • acknowledge that this formation creates an IAM role

Once deployed you can execute any test object with the lambda and it will reverse the strigified test object.

lambda_function.py

from __future__ import print_function

import json
import os
from subprocess import Popen, PIPE

def run_exec(*args, **envArgs):
    env = dict(os.environ)
    env.update(envArgs)
    return Popen(args, stdin=PIPE, stdout=PIPE, stderr=PIPE, env=env)


def handler(event, context):
    cwd = os.path.abspath( os.getcwd() )
    exe = os.path.join(cwd, "reverse_cat")
    lib = os.path.join(cwd, "lib")

    proc = run_exec(exe, LD_LIBRARY_PATH=lib)

    proc.stdin.write(json.dumps(event, indent=2))
    proc.stdin.close()

    # ran successfully
    exitcode = proc.wait()
    if exitcode == 0:
        msg = ''.join(proc.stdout.readlines())
        print(msg)
        return msg
    else:
        raise Exception("exitcode of %d" % exitcode)

Makefile

S3_BUCKET = YOUR_BUCKET
S3_PREFIX = YOUR_PATH

all: build

upload: reverse_cat.zip reverse_cat_cf_template.json
	aws s3 cp reverse_cat.zip s3://$(S3_BUCKET)/$(S3_PREFIX)/reverse_cat.zip
	aws s3 cp reverse_cat.zip s3://$(S3_BUCKET)/$(S3_PREFIX)/reverse_cat_cf_template.json

build: reverse_cat.zip

reverse_cat.zip: lib reverse_cat lambda_function.py
	zip -r reverse_cat.zip lib/ reverse_cat lambda_function.py

reverse_cat: ReverseCat.exe
	mkbundle -o reverse_cat ReverseCat.exe --deps

ReverseCat.exe: ReverseCat.cs
	mcs ReverseCat.cs

lib: reverse_cat
	mkdir lib
	ldd reverse_cat | awk '/=> \/usr/ { print ("cp " $$3 " lib"); }' | /bin/sh

clean:
	rm -f reverse_cat
	rm -rf lib
	rm -f ReverseCat.exe
	rm -f reverse_cat.zip

reverse_cat_cf_template.json

{
    "Description": "Reverse Cat Lambda",
    "Parameters": {
        "S3Bucket": {
            "Type": "String"
        },
        "S3Key": {
            "Type": "String"
        }
    },
    "Resources": {
        "Lambda": {
            "Properties": {
                "Code": {
                    "S3Bucket": {
                        "Ref": "S3Bucket"
                    },
                    "S3Key": {
                        "Ref": "S3Key"
                    }
                },
                "Description": "Lambda which executes mono executable `reverse_cat`",
                "Handler": "lambda_function.handler",
                "MemorySize": 128,
                "Role": {
                    "Fn::GetAtt": [
                        "LambdaRole",
                        "Arn"
                    ]
                },
                "Runtime": "python2.7",
                "Timeout": 30
            },
            "Type": "AWS::Lambda::Function"
        },
        "LambdaRole": {
            "Properties": {
                "AssumeRolePolicyDocument": {
                    "Statement": [
                        {
                            "Action": "sts:AssumeRole",
                            "Effect": "Allow",
                            "Principal": {
                                "Service": "lambda.amazonaws.com"
                            }
                        }
                    ],
                    "Version": "2012-10-17"
                },
                "Policies": [
                    {
                        "PolicyDocument": {
                            "Statement": [
                                {
                                    "Action": [
                                        "logs:CreateLogGroup",
                                        "logs:CreateLogStream",
                                        "logs:PutLogEvents"
                                    ],
                                    "Effect": "Allow",
                                    "Resource": "arn:aws:logs:*:*:*"
                                }
                            ],
                            "Version": "2012-10-17"
                        },
                        "PolicyName": "LambdaRolePolicy"
                    }
                ]
            },
            "Type": "AWS::IAM::Role"
        }
    }
}

ReverseCat.cs

using System;
using System.Collections.Generic;

public class ReverseCat
{
    static public void Main ()
    {
        List<string> input = new List<string>();
        string line;
        while ((line = Console.ReadLine()) != null) {
            input.Add(line);
        }

        char[] linesArray = String.Join("\n", input.ToArray()).ToCharArray();
        Array.Reverse(linesArray);
        
        Console.WriteLine (new string(linesArray));
    }
}