Flynn is an open-source Platform as a Service (PAAS) that is modular and based on Dokku. It uses Docker containers and builds "slugs" from application source code similar to Heroku. The core Flynn components include a host service, service discovery system, controller, CLI, deployer, slug builder, and slug runner. It allows pushing code to Flynn which compiles a slug, hosts it on a file server, launches it in Docker containers, and sets up routing. While rough around the edges for managing clusters, Flynn has potential due to its small reusable components and ability to manage general containers beyond just applications.

1. Build your own PAAS with Flynn
Jonathan Manuzak
@jonmanuzak

2. Docker is great…
… but normal people need glue.
Pain-relief As A Service?

3. The Project
• A modular, open-source PAAS
• Based on Jeff Lindsay’s Dokku
– ‘The smallest PAAS implementation you’ve ever
seen’
• Heavily inspired by Heroku
• Open source project launched in early 2013
• Became not so open in late 2013
• Asked for sponsorship from the community

4. The People
Jonathan Rudenberg Daniel Siders Jeff Lindsay

5. The Tech
• A lot of Go goodness
• Service discovery is a core component
• CLI means happy devs and ops teams
• Can run persistent ‘appliances’
• Unix tool philosophy

6. The Tech
• Layer 0
– flynn-host - The Flynn host service
– discoverd - The Flynn service discovery system
• Layer 1
– flynn-controller - Controller for the management of applications running via
an HTTP API
– flynn-bootstrap - Bootstraps Flynn Layer 1
– gitreceived - An SSH server made specifically for accepting git pushes
– flynn-cli - Command-line Flynn HTTP API client
– flynn-receive - Flynn’s git deployer
– slugbuilder - A tool using Docker and Buildpacks to produce a Heroku-like slug
– Slugrunner - A Docker container that runs Heroku-like slugs produced by
slugbuilder.
– flynn-dev- Flynn development environment in a VM
– strowger -Flynn TCP/HTTP router
– shelf - A simple, fast HTTP file service
– Sdutil - Service discovery utility for systems based on go-discover
– flynn-postgres - Flynn PostgreSQL database appliance
– taffy - Taffy pulls repos and deploys them to Flynn

7. DEMO

8. What just happened?
• Push repo to Flynn
• Flynn compiles a slug
• Hosts the slug on a file server
• Launches slug in docker container(s)
• Wires routes and starts load balancer

9. The slugrunner
• Obligatory Dockerfile
• Runner executes the slug and registers
services
• Heavy Heroku inspiration
– Installs java, python, ruby, git

10. Model Cement -> Elmers

11. Rough around the edges
• Difficult to manage remote clusters from CLI
• Web interface needs polish and features
– Can’t delete apps?
• Scaling across multiple hosts isn’t configurable
• Not much fault tolerance

12. Packed with potential
• Small reusable components
• Not difficult to imagine Flynn managing
containers rather than “apps”

13. That’s all folks