Social Media App

Guide

This repo has been created while following this tutorial by Sanjeev Thiyagarajan, modified to use MongoDB as the database.

Objective

The objective of the repo is to create a twitter-like social media application backend using FastAPI and MongoDB.

Tech Stack

The backend has been built on the following web technologies:

• API Framework: FastAPI
• Database: MongoDB
• Database Driver: Motor
• ODM: Beanie
• Web Server: Uvicorn and Gunicorn

Deployment

Creating Environment Variables

The simpler way is to create a .env file in the home directory and utilize that. However, we usually want to avoid this approach since the file can accidentally be uploaded to the repo. Alternatively:

• Place the .env file in the home folder /home/ubuntu/
• Edit the .profile file in the home folder with the following command so that it triggers automatically when the system is started:

set -o allexport; source /home/ubuntu/.env; set +o allexport

Testing with Uvicorn

• Run:

uvicorn --host 0.0.0.0 app.main:app

• Test by going to {Public IP}:8000 and {Public IP}:8000/docs

Testing with Gunicorn

• Run:

gunicorn -w 4 -k uvicorn.workers.UvicornWorker app.main:app --bind 0.0.0.0:8000

• Test by going to {Public IP}:8000 and {Public IP}:8000/docs

• The output to the command should show 4 workers with 1 parent process

Converting the API into a Service

• Get python path by executing which gunicorn

• Go to /etc/systemd/system

• Create a new file called api.service with the following:

[Unit]
Description=FastAPI server service
After=network.target

[Service]
User=ubuntu
Group=ubuntu # same as User
WorkingDirectory=/home/ubuntu/src # whatever is the location of your application folder
Environment="PATH=/home/ubuntu/bin" # the bin location you got from which gunicorn
EnvironmentFile=/home/ubuntu/.env # the location to the .env file
ExecStart=/home/ubuntu/bin/gunicorn -w 4 -k uvicorn.workers.UvicornWorker app.main:app --bind 0.0.0.0:8000 # use the location you got from which gunicorn

[Install]
WantedBy=multi-user.target

• Note: the .profile edit to automatically import environment variables is no longer required

• Run: sudo systemctl start api

• Verify it is running with sudo systemctl status api

• Test by going to {Public IP}:8000 and {Public IP}:8000/docs

• Run: sudo systemctl enable api to force the service to restart on reboot

Setting up nginx

• Install nginx: sudo apt install nginx -y

• Start nginx: sudo systemctl start nginx

• Test by going to {Public IP} and it should show you an nginx welcome page

• Go to /etc/nginx/sites-available and open default

• Change the location block:

location / {
    proxy_pass http://localhost:8000;
    proxy_http_version 1.1;
    proxy_set_header X-Real-IP $remote_addr;
    proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
    proxy_set_header Upgrade $http_upgrade;
    proxy_set_header Connection 'upgrade';
    proxy_set_header Host $http_host;
    proxy_set_header X-NginX-Proxy true;
    proxy_redirect off;
}

• Run sudo systemctl restart nginx

• Test by going to {Public IP} and {Public IP}/docs and it should show you the API interface

Attaching a domain name

• This requires you to have a domain name attached to the {Public IP}

• As an example, attach both api.com and www.api.com to the {Public IP} through DNS records

• Test by going to api.com and api.com/docs

• Test by going to www.api.com and www.api.com/docs

Setting up an SSL certificate

• Go to Certbot instructions page

• Select nginx and Ubuntu 20

• Follow the guide to setup the certificate

• Make sure port 443 is open for HTTPS requests

• Test by going to api.com and api.com/docs; the connection should be encrypted

• Repeat the test for www.api.com