Daydream - Full stack in a nutshell

Work in progress

Overview

This is an experiment on developing full stack application in a completely different way.

• The core of the application is defined directly in Postgres using SQL, leveraging the power of Row Level Security and other features that the database offers
• PostgREST is used to automatically derive a HTTP API from the Postgres application
• All changes to the application state are tracked though an events service which is implemented in Haskell, leveraging the power of sum types to keep everything consistent
• All APIs are tied together using Openresty / Nginx as a reverse HTTP proyx and Lua for middleware tasks
• The frontend is written in Elm, with all API bindings generated from the Postgres application and events service
• All dependencies and build steps are managed with Nix
• Tests are set up for all levels of the stack, including integration tests written in Python and with Selenium

Running the application

It's possible to run a local instance of the application with one command, e.g.:

nix-shell --run daydream-local-watch

This takes care of everything from getting dependencies, setting up the database, spinning up and tying together the services and building the frontend with generated bindings. It offers a view on all logs, a bit like docker-compose and includes hot code reload for all modules.

No containers needed

The command show above is able to run completely locally without containers. All dependencies are managed by Nix and all working files are set up in a temporary directory, so there are no permanent changes to your machine. At the same time, containers for deployment are automatically built from the same source.

Why?

This experiment might yield a radically more efficient and maintainable way to write full stack applications. The combination of SQL on Postgres, PostgREST, Haskell, Openresty/Nginx, Lua, Elm, Nix and Python, while optionally running everything locally without containers might need getting used to. But it has many upsides:

• Less work and repetition: Almost all the APIs and frontend bindings are generated from the database schema
• High reliability: All dependencies kept consistent with Nix. The integrity of the application state is maintained directly at the core in the database, avoiding whole classes of bugs
• ...more fun! :-)