Managing multi-tenant SaaS apps can get tricky.
Each tenant usually needs:
- A unique subdomain
- A dedicated database
- A scalable backend to handle requests
Manually setting up subdomains and databases is painful. So… I automated it. 😎
In this guide, I’ll walk you through how I built an automatic subdomain + database provisioning system using:
AWS Route 53 → Manages subdomains
FastAPI → Handles tenant onboarding
MySQL → Stores tenant-specific data
NGINX → Routes traffic based on subdomain
Boto3 → Talks to AWS from Python
Let's dive in! 🏊♂️
🌐 Step 1 — Automate Subdomain Creation with Route 53
First, create a hosted zone in AWS Route 53 for your domain.
Install Boto3:
pip install boto3
Python Function to Create Subdomain:
import boto3
def create_subdomain(subdomain: str):
route53 = boto3.client('route53', region_name='ap-south-1')
hosted_zone_id = "ZXXXXXXXXXXX" # Replace with your Hosted Zone ID
domain_name = "example.com"
response = route53.change_resource_record_sets(
HostedZoneId=hosted_zone_id,
ChangeBatch={
"Changes": [
{
"Action": "CREATE",
"ResourceRecordSet": {
"Name": f"{subdomain}.{domain_name}",
"Type": "A",
"TTL": 300,
"ResourceRecords": [{"Value": "YOUR_SERVER_PUBLIC_IP"}]
}
}
]
}
)
return response
This automatically registers a new subdomain inside Route 53.
🛢️ Step 2 — Create Tenant Databases Dynamically
Each tenant gets a separate MySQL database for better isolation.
import mysql.connector
def create_tenant_db(tenant_name: str):
conn = mysql.connector.connect(
host="localhost",
user="root",
password="your_password"
)
cursor = conn.cursor()
cursor.execute(f"CREATE DATABASE IF NOT EXISTS {tenant_name}_db")
conn.commit()
conn.close()
⚡ Step 3 — FastAPI Endpoint for Tenant Signup
Whenever someone registers, we:
- Create their database
- Create their subdomain
- Return their live URL 🚀
from fastapi import FastAPI
app = FastAPI()
@app.post("/register")
async def register_tenant(tenant: str):
create_tenant_db(tenant)
create_subdomain(tenant)
return {"status": "success", "subdomain": f"{tenant}.example.com"}
🌍 Step 4 — Configure NGINX for Subdomains
We want all subdomains like client1.example.com or client2.example.com to hit the same backend, but serve different data.
Add this to your Nginx config:
server {
listen 80;
server_name ~^(?<subdomain>.+)\.example\.com$;
location / {
proxy_pass http://127.0.0.1:8000;
proxy_set_header Host $host;
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_set_header X-Forwarded-Proto $scheme;
}
}
Then reload NGINX:
sudo nginx -t
sudo systemctl reload nginx
🏗️ Final Architecture
Signup → FastAPI → Route 53 → NGINX → Tenant DB → Tenant-Specific App
This gives you:
- ✅ Automatic subdomain creation
- ✅ Automatic database provisioning
- ✅ Scalable multi-tenant architecture
🎯 Conclusion
With AWS Route 53, FastAPI, MySQL, and NGINX, we built a SaaS-ready system that provisions subdomains and databases automatically.
This approach works great for multi-tenant apps, platforms, and SaaS dashboards — and saves hours of manual setup.
💡 Pro Tip: You can even take it further and integrate AWS ACM for automatic SSL certificates per subdomain.
What do you think? Would you like me to share a guide on auto SSL + HTTPS for all subdomains next? 🔐