This document discusses functions-as-a-service (FaaS) and provides an introduction to using AWS Lambda. It outlines the advantages of FaaS such as infinitely scalable devops without server management. It demonstrates a basic "Hello World" Lambda function and connecting Lambda functions to MongoDB. It notes limitations such as cold start times and that database performance is more important than app servers for most use cases. It recommends FaaS for non performance-sensitive backends and provides further reading on serverless platforms and async/await.

1. A Practical Intro to
Functions-as-a-Service
Valeri Karpov
@code_barbarian
github.com/vkarpov15

2. About Me
● Backend Lead @ Booster, Node.js OSS
● Core contributor for Mongoose, Mocha
● Blogger, thecodebarbarian.com
● Early employee at LevelUp, MongoDB, Booster
● Invented the MEAN stack

3. What’s This Talk About?
● The advantages of FaaS over servers
● “Hello, World” with Node.js and AWS Lambda
● Bundling for Lambda
● Why we aren’t using FaaS for everything

4. What is Functions-as-a-Service?
● Deploy and run individual functions
● Billed for time elapsed and memory used
● AWS Lambda
● Microsoft Azure Functions
● Google Cloud, IBM Cloud, Oracle Fn, etc.

5. What Makes FaaS Great?
● DevOps is hard at scale
● Fleets of applications, some overprovisioned
● Infinitely* scalable DevOps strategy
● Managed HTTPS, no renewing LetsEncrypt

6. Hello, Lambda console.aws.amazon.com

7. A Basic Lambda Function
● Lambda is its own JS framework
● Much better in Node 8.x with async/await

8. Running a Lambda Function
● Can run a Lambda function from web UI

9. HTTP Endpoint for Lambda
● Requires AWS API Gateway, separate pricing

10. Using Open Source Modules
● Can also upload a zip file to Lambda
● Can manually add files to your zip
● Better: use Webpack
● See bit.ly/lambda-webpack

11. Connecting to MongoDB From Lambda

12. Warm vs Cold Lambdas
● Lambda can retain global state between runs
● Useful for db connections, slow otherwise
● Warm: Lambda retained db connection
● Cold: Lambda must create new db connection

13. Bundling with Webpack
● Webpack resolves require() imports
● See bit.ly/lambda-webpack

14. The Downsides of FaaS
● Startup time
● Vendor lock-in
● Doesn’t help with database performance

15. (Lack of) Speed Kills
● <= 50ms is considered instantaneous
● Creating a db connection can take seconds
● Lambda not “warm” if load too low or too high

16. FaaS is an Upselling Strategy
● You don’t use just AWS Lambda
● Cloudwatch Logs by default
● Want HTTP? AWS API Gateway
● Want custom domain? AWS Route 53
● Want HTTPS for custom domain? AWS ACM

17. Side Note: Self-Hosted FaaS
● Kubeless, Fission, OpenFaaS, BlueWhisk
● FaaS, but on your own infrastructure
● Theoretically avoids vendor lock-in
● Check out Express Serverless Platform

18. Database Perf Matters More
● Horizontal scaling for apps is limited
● Assume small company w/ 1-2 databases
● Booster: 8 figure revenue, 10M API reqs/day
● Average request: 98% of time waiting for db
● More app servers might help 0.1%

19. Summary
● FaaS is great for non-perf-sensitive backend
● 1 DevOps strategy for arbitrarily many “apps”
● No “how much memory does app X need?”
● Bundling and planning for function size
● FaaS is not great for traditional APIs

20. Further Reading
● My Blog:
○ Azure Functions: bit.ly/mongodb-azure
○ IBM Cloud: bit.ly/mongodb-ibm-cloud

21. Mastering Async/Await
asyncawait.net/wyncode

22. Thanks for Listening!
Slides on slideshare.net/vkarpov15