Existing Django Apps

If you have an existing Django app that you want to move over to Fly, this guide walks you through the initial deployment process and shows you techniques you can use to troubleshoot issues you may encounter.

Configure Django

The official How to Deploy Django guide and Django Deployment Checklist are a good first step to ensure your app is ready for deployment.

The third-party package WhiteNoise is recommended for serving static files in production as this requires additional configuration.

A production web server must be installed, typically either Gunicorn or uWSGI. The database adapter Psycopg is commonly used along with dj-database-url to establish a Django database connection via a DATABASE_URL environment variable.

Be sure to have generated an up-to-date requirements.txt file for any new packages added for deployment.

flyctl

Fly.io has its own command-line utility for managing apps, flyctl. If not already installed, follow the instructions on the installation guide and log in to Fly.

Provision Django and Postgres Servers

To configure and launch the app, use the command fly launch and follow the wizard. You can set a name for the app, choose a default region, launch and attach a Postgres database. You can also set up a Redis database though we will not be doing so in this example.

fly launch

Scanning source code
Detected a Django app
Creating app in ~/django-existing-app
We're about to launch your Django app on Fly.io. Here's what you're getting:

Organization: Jane Smith             (fly launch defaults to the personal org)
Name:         django-existing-app    (derived from your directory name)
Region:       Ashburn, Virginia (US) (this is the fastest region for you)
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? Yes
Opening https://fly.io/cli/launch/mo1ootho9ualooghoch3iih6cha2shah ...

Waiting for launch data... Done
Created app 'django-existing-app' in organization 'personal'
Admin URL: https://fly.io/apps/django-existing-app
Hostname: django-existing-app.fly.dev
Set secrets on django-existing-app: SECRET_KEY
Creating postgres cluster in organization personal
Creating app...
Setting secrets on app django-existing-app-db...
Provisioning 1 of 1 machines with image flyio/postgres-flex:15.3@sha256:44b698752cf113110f2fa72443d7fe452b48228aafbb0d93045ef1e3282360a6
Waiting for machine to start...
Machine 217811c53e0896 is created
==> Monitoring health checks
  Waiting for 217811c53e0896 to become healthy (started, 3/3)

Postgres cluster django-existing-app-db created
  Username:    postgres
  Password:    lt5JoEIVons5INJ
  Hostname:    django-existing-app-db.flycast
  Flycast:     fdaa:3:9f45:0:1::2
  Proxy port:  5432
  Postgres port:  5433
  Connection string: postgres://postgres:lt5JoEIVons5INJ@django-existing-app-db.flycast:5432

Save your credentials in a secure place -- you won't be able to see them again!

Connect to postgres
Any app within the Jane Smith organization can connect to this Postgres using the above connection string

Now that you've set up Postgres, here's what you need to understand: https://fly.io/docs/postgres/getting-started/what-you-should-know/
Checking for existing attachments
Registering attachment
Creating database
Creating user

Postgres cluster django-existing-app-db is now attached to django-existing-app
The following secret was added to django-existing-app:
  DATABASE_URL=postgres://django_existing_app:lt5JoEIVons5INJ@django-existing-app-db.flycast:5432/django_existing_app?sslmode=disable
Postgres cluster django-existing-app-db is now attached to django-existing-app
Wrote config file fly.toml

[INFO] Python 3.10.12 was detected. 'python:3.10-slim-bullseye' image will be set in the Dockerfile.

Validating ~/django-existing-app/fly.toml
Platform: machines
✓ Configuration is valid

Your Django app is ready to deploy!

For detailed documentation, see https://fly.dev/docs/django/

Dockerfile and fly.toml

The fly launch command creates two new files in the project that are automatically configured: Dockerfile and fly.toml.

The Dockerfile is essentially instructions for creating an image.

The fly.toml file is used by Fly.io to configure applications for deployment. Configuration of builds, environment variables, internet-exposed services, disk mounts and release commands go here.

HOSTS & CSRF_TRUSTED

The dedicated URL for your deployment will be <app_name>.fly.dev. Update the ALLOWED_HOSTS and CSRF_TRUSTED_ORIGINS configurations with your <app_name> to include it.

Deploy Your Application

To deploy the application use the following command:

fly deploy

This will take a few seconds as it uploads your application, verifies the app configuration, builds the image, and then monitors to ensure it starts successfully. Once complete, visit your app with the following command:

fly apps open

If everything went as planned you will see your Django application homepage.

Troubleshooting your initial deployment

Since this is an existing Django app, it is highly likely it might not boot because you probably need to configure secrets or other service dependencies. Let’s walk through how to troubleshoot these issues so you can get your app running.

View Log Files

If your application didn’t boot on the first deploy, run fly logs to see what’s going on.

fly logs

This shows the past few log file entries and tails your production log files. Additional flags are available for filtering.

Console

To SSH into your hosted Django application use the command fly ssh console. For example, to execute Django’s createsuperuser command to log into the admin do the following:

fly ssh console
# python manage.py createsuperuser

If you prefer, this can be run as one command instead:

fly ssh console --pty -C 'python /code/manage.py createsuperuser'

Secrets

Secrets allow sensitive values, such as credentials and API keys, to be securely passed to your Django applications. You can set, remove, or list all secrets with the fly secrets command.

Git

Deployments are initiated via the fly deploy command–git isn’t needed to deploy to Fly.io. The advantage of this approach is that your git history will be clean and not full of git push commits such as occurs on other hosting platforms.

This also means that .gitignore files are not ignored. If you have secrets or other sensitive information in your git history, it is recommended to create a .dockerignore file and add the git repo there.

Databases

Fly.io has a Postgres offering to automate provisioning, maintenance, and snapshot tasks for your Postgres database, but it does not manage it. If you run out of disk space, RAM, or other resources on your Fly Postgres instances, you’ll have to scale those virtual machines from the Fly CLI. If you prefer, you can instead connect to an external fully-managed Postgres database.

Custom Domain & SSL Certificates

After you finish deploying your application to Fly.io and have tested it extensively, read through the Custom Domain docs and point your domain at Fly.

In addition to supporting CNAME DNS records, Fly.io also supports A and AAAA records for those who want to point example.com (without the www.example.com) directly at Fly.

flyctl Commands

The flyctl CLI docs have an extensive inventory of fly commands. Here are a few common commands especially if you are coming from another hosting service like Heroku.

Additional resources

• flyctl - The Fly.io CLI
• Fly Postgres