#introToAWSLambda Introduction to AWS Lambda

What is Lambda

• 60 seconds or less
• NodeJS, Java8, Bash, Awk, Python2.7, or static binary
• More RAM = more CPU slice
• Around 100 concurrent jobs allowed

The Lambda environment

See [LambdaSh] (https://github.com/alestic/lambdash) if you want to explore the AWS Lambda environment with interactive shell commands.

• Running Bash scripts on Lambda

Doug McIlroy's word frequency program in response to Knuth's 10 pages of Pascal.

#!/bin/bash
#Doug McIlroy 1986
tr -cs A-Za-z '\n' |
tr A-Z a-z |
sort |
uniq -c |
sort -rn |
sed ${1}q

Let run this on Mark Twain's "A Connecticut Yankee in King Arthur's Court".

$ cat yankee.txt | ./wordFreq.sh
6093 the

Our wordfreq lambda function:

console.log('Loading function');

var exec = require('child_process').exec;

exports.handler = function(event, context) {
 exec('echo '+ event.key1 + '| sh ./wordFreq.sh', function(error, stdout) {
        context.done(error, stdout);
    });
};

• event is the JSON we pass our AWS Lambda function.
• Usually call your main handler file index.js

#Don't do this
zip -r mylamda.zip mylambda
#Do this
cd mylambda
zip -r mylambda.zip ./*

I build my lambdas on ec2 then copy them to my box before uploading

 scp -i "apair.pem" ec2-user@54.56.333.229:mylambda.zip mylambda.zip

Compiling for Lambda

• Set up an EC2 instance on AWS Linux
• Generate a key pair so you can ssh into it
• For C++/Haskell download/build static libraries to link with
• Use the ldd command to find your grocery list of static libraries. Example: ldd a.out
• See stack discussion
• See GHC discussion

sudo yum update
sudo yum install nodejs npm --enablerepo=epel

ghc hello.hs 
./hello 
du -h hello
strip hello
du -h hello

#Fast Fibbonaci

• Take Fib Finite State Automata where 'b' may not repeat and each word must start 'a' and end 'a':

• ()|a|aa|aba,aba|aaaa,aaba,abaa|aaaaa,aaaba,aabaa,abaaa,ababa|...

• Take that adjacency matrix and take it to the nth power with binary doubling

• Use GNU MP for large Integers

• The i,j entry is now words of length n that start at letter i and end at letter j

• Optimize: 0 x thing = 0; 1 x thing = thing

import System.Environment

fastFib' :: Integer -> (Integer, Integer)
fastFib' 0 = (0, 1)
fastFib' n =
  let (a, b) = fastFib' (div n 2)
      c = a * (b * 2 - a)
      d = a * a + b * b
  in if mod n 2 == 0
    then (c, d)
    else (d, c + d)

fastFib :: Integer -> Integer
fastFib n = fst (fastFib' n)

main = do
    args <- getArgs
    let numberStr = head args
    let number = read numberStr :: Integer
    print (fastFib number)

ghc FastFib.hs -O2 -o FastFib -threaded -static -optl-static
strip FastFib

console.log('Loading function');

var exec = require('child_process').exec;

exports.handler = function(event, context) {
 exec('./FastFib '+ event.key1 , function(error, stdout) {
        context.done(error, stdout);
    });
};

API Gateway trigger for AWS Lambda

curl -H "Content-Type: application/json" -X POST -d "{\"key1\": \"30\"}" https://pekdudne7d.execute-api.us-east-1.amazonaws.com/prod

The two zip files have been precompiled on AWS Linux. Enjoy.

Update

I now compile locally using the lambci/lambda Docker container. To move files out use:

docker cp <containerId>:/file/path/within/container /host/path/target