GNUHealth deployment using Nix and Docker

This repository defines a Docker image for GNUHealth, packaged with Nix for ease of customization and reproducible deployment.

Docker images produced here should be easy to deploy to cloud services. The code here uses Fly.io, but it should be simple to adapt to other platforms.

A deployment done for the Tashkent State Dental Institute can be found here.

Configuring modules

Modules can be defined in the release.nix file. The appropriate versions of modules can be found here.

Setting up Fly.io

Make sure to create an account with access to the free tier.

The following commands should be executed inside the Nix shell, by running nix-shell before starting.

First, to login, run:

$ flyctl auth login

Then, the Postgres database must be created:

$ flyctl postgres create

This command will show the credentials, which should be saved in a secrets.json file as:

{
  "pgstring": "postgresql://user:password@host:port"
}

Finally, create your app:

$ flyctl launch

In this step you will choose the app name, which will determine its URL. This name should be used for the tag-and-push-image

In the following, the app name will be called $APP_NAME.

Make dure the image is in the fly.toml configuration file:

[build]
  image = "registry.fly.io/$APP_NAME:latest"

Save this name in the secrets.json file:

{
  "app_name": "$APP_NAME",
  "pgstring": "postgresql://user:password@host:port"
}

Building and deploying

Once more, all commands should be run inside the Nix shell, by running nix-shell before starting.

First, build the docker image and load it:

$ just build-and-load-image

Tag the image conveniently, and push it:

$ just tag-and-push-image $APP_NAME

And finally, deploy:

$ just deploy $APP_NAME

About the implementation

GNUHealth is implemented as a series of modules for Tryton. Therefore, the work here consisted on making these modules available in a place where Tryton can find them. The same Python executable will be used to run Tryton as well as its modules, so all dependencies must be available to it.