This repository contains unofficial patterns, sample code, or tools to help developers build more effectively with Fauna. All Fauna Labs repositories are provided “as-is” and without support. By using this repository or its contents, you agree that this repository may never be officially supported and moved to the Fauna organization.

---

Python Fly.io starter for Fauna

Fauna is a distributed relational database with a document data model. Delivered as an API, Fauna is automatically configured – out of the box – as a three replica database with active-active write capability, making it a powerful complement to Fly.io in serving low latency reads and writes for dynamic global applications.

This starter kit provides a sample Fauna integration with Python and Flask, and configured to run on Fly.io. Whether or not you plan to deploy on Fly, this sample should nevertheless provide a great Fauna example for Python/Flask.

---

Prerequisites

• Python 3.9 or greater
• flyctl

Create a Fauna database and generate an access key

• Signup for a Fauna account if you don't have one already.
• Create a database and database access token according to these instructions.
• Copy the .env.example file (in the root of this project) into a new file named .env and populate the variable FAUNA_SECRET_KEY with the database access token from above. Leave FLASK_APP as-is:

  export FAUNA_SECRET_KEY="xxxxxxxx-xxxxxxxxx"
  export FLASK_APP="server"
  

Test locally

python3 -m venv venv

Activate venv

source venv/bin/activate

Install requirements

pip install -r requirements.txt

Source env variables

source .env

Now, load some sample data:

python sample/load.py

Run Flask

flask run

Navigate to http://127.0.0.1:5000/read

This should perform a read from the Fauna database you created and populated with sample data, per the setup steps above.

Deploy to Fly.io

To launch the app on fly, run fly launch --no-deploy in the root directory of this project. You will be prompted for a couple things:

• ? Would you like to copy its configuration to the new app? (y/N) Choose y (Yes)
• ? Do you want to tweak these settings before proceeding? (y/N) Choose N (No)

% fly launch --no-deploy
An existing fly.toml file was found for app python-fauna-starter
? Would you like to copy its configuration to the new app? Yes
Using build strategies '[a buildpack]'. Remove [build] from fly.toml to force a rescan
Creating app in <folder>/python-fly-io-starter
We're about to launch your app on Fly.io. Here's what you're getting:

Organization: <your org name>           (fly launch defaults to the personal org)
Name:         python-fauna-starter      (from your fly.toml)
Region:       San Jose, California (US) (from your fly.toml)
App Machines: shared-cpu-1x, 1GB RAM    (most apps need about 1GB of RAM)
Postgres:     <none>                    (not requested)
Redis:        <none>                    (not requested)

? Do you want to tweak these settings before proceeding? No
Created app 'python-fauna-starter' in organization 'personal'
Admin URL: https://fly.io/apps/python-fauna-starter
Hostname: python-fauna-starter.fly.dev
Wrote config file fly.toml
Validating <folder>/python-fly-io-starter/fly.toml
Platform: machines
✓ Configuration is valid
Your app is ready! Deploy with `flyctl deploy`

Environment variables are not uploaded. Before deploying, you should set the Secrets value for FAUNA_SECRET_KEY:

fly secrets set FAUNA_SECRET_KEY="<fauna secret key>"

Now you can deploy:

fly deploy

Once the application has been deployed, you can find out more about its deployment.

fly status

Browse to your newly deployed application with the fly open command.

% fly open

Opening https://<a-new-app-name>.fly.dev

Scale your deployment to match the Fauna footprint

When you create a database in Fauna, it is automatically configured – out of the box – as a three replica database with active-active write capability (For example, if you created a database in the "US Region Group", there will be 3 replicas of the database across the United States). Thus, a good way to take advantage of this architecture is to deploy on 3 Fly.io regions as well, as close as possible to the database replicas.

Currently, Fauna provides 2 choices of Regions Groups, US and EU. The table below lists the Fly regions that are closest to the Fauna replicas of each respective region group:

Fauna Region Group	Deploy on Fly Regions
EU	lhr, arn, fra
US	sjc, ord, iad

For example, let's say you created your Fauna database in the US Region Group. This starter kit is provided with a default fly.toml file with primary_region set to sjc. Unless you edited this value, deploying this starter kit leaves you with your Fly app in sjc. To take full advantage of Fauna’s distributed footprint, add additional Fly machines in the other 2 regions closest to the Fauna replicas by running this command:

fly scale count 2 --region ord,iad

Then, run fly scale show to see where your app’s Machines are running. For example:

$ fly scale show

VM Resources for app: my-app-name

Groups
NAME    COUNT   KIND    CPUS    MEMORY  REGIONS
app     3       shared  1       256 MB  iad,ord,sjc

There is nothing else that needs to be updated in the code or Fauna configuration, because Fauna automatically routes requests to the closest replica based on latency and availability.