This is a simple example for deploying a FastAPI application, to production environment. And probably the easiest way to run an application with secure SSL/HTTPS, and with Caddy server magic. So, you can focus just your application and code, not deployment process :)

What we need ?

• Linux machine/VM
• Domainname
• FastAPI application
• Caddy server and reverse proxy configuration for HTTPS/SSL

Linux VM :

You can order a Linux VM from the Digital Ocean, Contabo, Vultr, Linode etc. For this tutorial, we choose an Debian instance on Contabo. After first login, run:

sudo apt-get update

If sudo not working on Debian:

apt install sudo

It's optional add a new user, or continue with "root" user. But we choose and recommend a new user, and give it admin privileges.

sudo adduser <newuser>

sudo usermod -aG <newuser>

Change root user to new user

su <newuser>

python3 -m pip install fastapi[all] gunicorn uvicorn

If "pip" not working, so install python3 pip

sudo apt install python3-pip

Domain configuration

We need a domain name for publishing our application in World Wide Web. We choose a domainname from the https://www.namecheap.com. And we must tell the domain provider which server/IP provider will be used for publishing. Our FastAPI application will be served on Contabo. From domain list => management => Nameservers => Custom DNS add three nameservers (ns1.contabo.net, ns2.contabo.net, ns3.contabo.net) and save.

From Contabo "DNS Zone Management", add your domainname to "Domain", and "Target IP address" select your VM instance/IP from dropdown menu => then click "create zone".

FastAPI application

As we mentioned above that, this is just a demo application. For demonstration perposes

nano main.py

from fastapi import FastAPI

app = FastAPI()


@app.get("/items/{item_id}")
async def read_item(item_id: int):
   return {"item_id": item_id}

 

For testing just run:

uvicorn main:app --reload

If it's running without error, so vi need make a "service" or "supervisor" for our FastAPI application. The reason for that, to do application more robust and relable for pruduction. After that you can start, stop and see status just from the command line.

To do that run:

sudo nano /etc/systemd/system/fastapi.service

and copy-paste the code block below

[Unit]
Description=fastapi service
After=network.target

[Service]
User=<newuser>
Group=www-data
WorkingDirectory=/home/<newuser>/fastapi
ExecStart=gunicorn main:app --workers 4 --worker-class uvicorn.workers.UvicornWorker --bind 0.0.0.0:8000

Restart=always

[Install]
WantedBy=multi-user.target

Hit "Ctrl+X" then "Y" for save the "fastapi.service" (For Nano editor)

Now our FastAPI application more robust and easy to control. For start and enable the service, run:

sudo systemctl start fastapi

To enable the service:

sudo systemctl enable fastapi

To stop the service:

sudo systemctl stop fastapi

To see status of the service:

sudo systemctl status fastapi

● fastapi.service - fastapi service
     Loaded: loaded (/etc/systemd/system/fastapi.service; enabled; vendor preset: enabled)
     Active: active (running) since Sat 2023-04-22 21:52:48 CEST; 15h ago
   Main PID: 333920 (gunicorn)
      Tasks: 5 (limit: 9507)
     Memory: 82.6M
        CPU: 8min 26.889s
     CGroup: /system.slice/fastapi.service
             ├─333920 /usr/bin/python3 /usr/bin/gunicorn main:app --workers 4 --worker-class uvicorn.workers.UvicornWorker --bind 0.0.0.0:8000
             ├─333921 /usr/bin/python3 /usr/bin/gunicorn main:app --workers 4 --worker-class uvicorn.workers.UvicornWorker --bind 0.0.0.0:8000
             ├─333922 /usr/bin/python3 /usr/bin/gunicorn main:app --workers 4 --worker-class uvicorn.workers.UvicornWorker --bind 0.0.0.0:8000
             ├─333923 /usr/bin/python3 /usr/bin/gunicorn main:app --workers 4 --worker-class uvicorn.workers.UvicornWorker --bind 0.0.0.0:8000
             └─333924 /usr/bin/python3 /usr/bin/gunicorn main:app --workers 4 --worker-class uvicorn.workers.UvicornWorker --bind 0.0.0.0:8000

Apr 22 21:52:48 vmi1180878.contaboserver.net gunicorn[333924]: [2023-04-22 21:52:48 +0200] [333924] [INFO] Application startup complete.
Apr 22 22:03:18 vmi1180878.contaboserver.net gunicorn[333923]: [2023-04-22 22:03:18 +0200] [333923] [WARNING] Invalid HTTP request received.

Now everything is working properly with HTTP on port 8000. But we need SSL/HTTPS,and configure Caddy server for reverse proxy.

Caddy Server configuration

Installation:

https://caddyserver.com/docs/install#debian-ubuntu-raspbian

sudo apt install -y debian-keyring debian-archive-keyring apt-transport-https

curl -1sLf 'https://dl.cloudsmith.io/public/caddy/stable/gpg.key' | sudo gpg --dearmor -o /usr/share/keyrings/caddy-stable-archive-keyring.gpg

curl -1sLf 'https://dl.cloudsmith.io/public/caddy/stable/debian.deb.txt' | sudo tee /etc/apt/sources.list.d/caddy-stable.list

sudo apt update

sudo apt install caddy

Configuration reverse proxy with Caddyfile

sudo nano /etc/caddy/Caddyfile

yourdomainname.net {

        reverse_proxy  localhost:8000

}

sudo systemctl reload caddy

Done !

Happy coding with awasome FastAPI :)