Why Fly.io


Showcasing a demo of Seedcase software helps make things more tangible. This post describes our reasons for using Fly.io as a deployment host for showcasing our demo.


Philip Christiansen


December 8, 2023


February 26, 2024

Context and Problem Statement

We need some way to test and visually see how Seedcase deploys and works “live”. The best solution would be to use a cloud provider, so we can easily deploy and visualize the progress of Seedcase.

This is relevant for reviewing code changes and for manual and user-experience testing. Ideally, this environment should be similar to a future production environment, but this may vary a lot based on the team/organisation that will use Seedcase.

So our question is:

Which cloud hosting provider should we use for our demonstrating and testing purposes?

Decision Drivers

We want to decide on a cloud provider based on these features/metrics:

  • Price: Relatively inexpensive in costs, since it will only be for demonstration purposes.
  • Easy of use: It shouldn’t be too difficult to use.
  • Customisable: The provider should be easy to customise to use different frameworks/tools, if we need to adjust. For instance we should be able to use either of: venv, poetry, docker and etc.
  • GitHub Authentication: The cloud provider should integrate with GitHub Authentication, because we already use GitHub for the Seedcase repositories and project management.
  • GitHub Actions Integration: The cloud provider should integrate with GitHub Actions, allowing us to create pipelines easily.
  • Managed PostgreSQL: It should have a managed PostgreSQL database to store application data if needed.
  • “Native” support for Django application: It should have support for running a Django application without the need to wrap it in package or Docker container.
  • Docker image or Dockerfile support: The cloud provider should also have support for running Docker images. Potentially, providing a Dockerfile would be convenient.
  • Docker-compose support: A cloud provider with docker-compose support would allow us to easily spin up complicated environment (application, database and etc) in a similar way as we do locally.
  • Logging and alerting: Logging and alerts would be nice features for the cloud provider, but not so relevant (and, therefore, not required) for a demo environment.
  • Similar to production environment: We want the demo environment to be similar to the production environment, but this may vary a lot based on the team/organisation using the software.

Considered Options

We have considered five different cloud providers: Azure, Render, Digital Ocean, Vercel and Fly.io . Below you see a “decision matrix” based on the different features.

Azure Render Digital Ocean Vercel Fly.io
Price (per month) 1000kr Free or 19$ user + 20$ DB ? Free or 20$ user Cost for usage only
Ease of use Hard Easy Medium Easy Easy / Medium
Customizability (venv, Poetry, Docker) High Medium High Low Medium
GitHub Authentication No Yes Yes Yes Yes
GitHub Actions Integration Very good Sort of (deploy webhook) Yes Yes Very good
Managed Postgres Yes Yes Yes Yes Yes (sort of)
File Storage service Yes Yes (FTP) 0.25$/GB Yes ($0.15 GB)
Native support for Django app Sort of Yes (Poetry support) ? Yes (requirements.txt) No
Docker Image or Dockerfile support Yes Yes Yes No Yes
Docker-compose Yes No (but has render.yml) Yes (with a normal node) No No
Logging Very good logs Simple Simple Simple Yes
Alerts Yes No ? No ?
Similar to production environment (Aarhus University server) Likely possible Maybe if Docker on university server Likely No Yes if docker

Decision Outcome

We have decided to utilise Fly.io for our demo and testing needs. Fly.io is very cheap and the cost is not based on the number of users - only the actual usage (around 1$). It integrates with GitHub and the deployment is easy to setup with a GitHub action. This part is less user-friendly than Render and Vercel, where the deployment happens automatically. However, we would eventually adjust this “magic deployment” anyway to do tests and etc. before deploying.

Fly.io uses Docker images, so there is no “native” support for a Django application, but flyctl automatically creates a Dockerfile which makes it easy anyway.

Fly.io automatically and relatively quickly scales up an app when needed, which makes it very cheap. Furthermore, Fly.io owns all the servers, which makes it cheap compared to other providers which are usually relying on AWS or Azure.

Fly.io has a customisable metrics dashboard (every app has access to Prometheus and Grafana).

The other cloud providers, where not chosen for these reasons:

  • Render was our initial choice. It was cheap and easy to setup, but the cost is per user plus the usage (around 100$ per month vs 1$ for Fly). Render is very user friendly with magic deployments, but we would need to adjust these anyway for test and etc.
  • Azure is able to do everything we require, but it is too complicated for a demo environment.
  • Vercel is easy to use, but lacks customisability. For instance, it seemed not to work so well with Poetry and it is unable to work with Docker.
  • Digital Ocean could be a fair choice, but I was unable to make it work - so in that sense it fails the “ease of use”-criteria.


  • PostgreSQL is a natural part of Fly.io, but it is not a Managed PostgreSQL like the other cloud providers. A PostgreSQL is “just an app” in Fly.io, so it might require a bit more maintenance. However, even in the unlikely scenario of complete data loss, there is no significant impact since Fly.io serves solely as a demonstration environment.
  • Storage is cheap in Fly.io, but there are some limitations Volume considerations. But again this is only a demo environment
  • Fly.io lacks docker-compose support, so we will not be able to reuse docker-compose files from our local development.