I was recently reminded of the concept of the Twelve-Factor App. As a methodology, I’ve read about it many times, and most of the concepts are by now second nature to me when I’m designing software and larger systems with a software-as-a-service model. If you’re not already familiar, I suggest you read the full description. In summary the twelve factors are:

1. Codebase One codebase tracked in revision control, many deploys
2. Dependencies Explicitly declare and isolate dependencies
3. Config Store config in the environment
4. Backing services Treat backing services as attached resources
5. Build, release, run Strictly separate build and run stages
6. Processes Execute the app as one or more stateless processes
7. Port binding Export services via port binding
8. Concurrency Scale out via the process model
9. Disposability Maximize robustness with fast startup and graceful shutdown
10. Dev/prod parity Keep development, staging, and production as similar as possible
11. Logs Treat logs as event streams
12. Admin processes Run admin/management tasks as one-off processes