Hello, tech enthusiasts! \ud83d\udc4b<\/p>\n\n\n\n
You built a small Python tool. Maybe it shows a sales summary, or it lets your team look up invoice status. It works great on your laptop. But when your laptop is off, nobody can use it.<\/p>\n\n\n\n
The answer is a VPS<\/strong>, a Virtual Private Server. Think of it as renting a small computer in a data centre. It is always on and always online, and small ones cost only a few dollars a month.<\/p>\n\n\n\n Today we will rent one, connect safely, and put a tiny Flask app online.<\/p>\n\n\n\n Pick any hosting provider and create the smallest Ubuntu server. You will get its IP address.<\/p>\n\n\n\n SSH<\/strong> is a safe tunnel to type commands on the server. Instead of a password, we use an SSH key<\/strong>. A key is like a house key that only you have: much harder to guess than a password.<\/p>\n\n\n\n On your own computer, create a key:<\/p>\n\n\n\n Most providers let you paste your public<\/strong> key (the file ending in First, install all updates:<\/p>\n\n\n\n Working as Log out and connect again as Install Python tools and nginx:<\/p>\n\n\n\n Make a folder and a virtual environment<\/strong>. A venv is a private box for your app’s libraries, so they do not mix with the system.<\/p>\n\n\n\n Create Flask’s built-in server is only for testing. Gunicorn<\/strong> is a real web server for Python apps. Test it:<\/p>\n\n\n\n Press Ctrl+C to stop. Now we want it to start by itself, even after a reboot. That is the job of systemd<\/strong>, Linux’s service manager. Create Start it and enable it at boot:<\/p>\n\n\n\n Nginx<\/strong> is like a receptionist. It receives visitors on the normal web port (80) and passes them to gunicorn. It is fast and safe. Create Enable it, remove the default site, test and reload:<\/p>\n\n\n\nWhat you need<\/h3>\n\n\n\n
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ssh<\/code> built in)<\/li>\n\n\nStep 1: Rent the server and connect with SSH keys<\/h3>\n\n\n\n
ssh-keygen -t ed25519<\/code><\/pre>\n\n\n\n.pub<\/code>) when you create the server. Do that. Then connect (replace the address with your server’s IP):<\/p>\n\n\n\nssh root@203.0.113.10<\/code><\/pre>\n\n\n\nStep 2: Update and create a normal user<\/h3>\n\n\n\n
apt update && apt upgrade -y<\/code><\/pre>\n\n\n\nroot<\/code> all the time is risky. Create a normal user with admin rights and copy your key to it:<\/p>\n\n\n\nadduser deploy\nusermod -aG sudo deploy\nrsync --archive --chown=deploy:deploy ~\/.ssh \/home\/deploy<\/code><\/pre>\n\n\n\nssh deploy@203.0.113.10<\/code>. Once that works, turn off password logins. Open \/etc\/ssh\/sshd_config<\/code>, set PasswordAuthentication no<\/code>, check that no file in \/etc\/ssh\/sshd_config.d\/<\/code> sets it back to yes<\/code>, then run sudo systemctl restart ssh<\/code>.<\/p>\n\n\n\nStep 3: Create the Python app<\/h3>\n\n\n\n
sudo apt install -y python3-venv nginx<\/code><\/pre>\n\n\n\nmkdir ~\/myapp && cd ~\/myapp\npython3 -m venv venv\nsource venv\/bin\/activate\npip install flask gunicorn<\/code><\/pre>\n\n\n\napp.py<\/code>:<\/p>\n\n\n\nfrom flask import Flask\n\napp = Flask(__name__)\n\n@app.route(\"\/\")\ndef home():\n return \"Hello from my first server!\"<\/code><\/pre>\n\n\n\nStep 4: Run it with gunicorn and systemd<\/h3>\n\n\n\n
gunicorn --workers 2 --bind 127.0.0.1:8000 app:app<\/code><\/pre>\n\n\n\n\/etc\/systemd\/system\/myapp.service<\/code> with sudo nano<\/code>:<\/p>\n\n\n\n[Unit]\nDescription=My Flask app\nAfter=network.target\n\n[Service]\nUser=deploy\nWorkingDirectory=\/home\/deploy\/myapp\nExecStart=\/home\/deploy\/myapp\/venv\/bin\/gunicorn --workers 2 --bind 127.0.0.1:8000 app:app\nRestart=always\n\n[Install]\nWantedBy=multi-user.target<\/code><\/pre>\n\n\n\nsudo systemctl daemon-reload\nsudo systemctl enable --now myapp\nsudo systemctl status myapp<\/code><\/pre>\n\n\n\nStep 5: Put nginx in front<\/h3>\n\n\n\n
\/etc\/nginx\/sites-available\/myapp<\/code>:<\/p>\n\n\n\nserver {\n listen 80;\n server_name example.com;\n\n location \/ {\n proxy_pass http:\/\/127.0.0.1:8000;\n proxy_set_header Host $host;\n proxy_set_header X-Real-IP $remote_addr;\n proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;\n proxy_set_header X-Forwarded-Proto $scheme;\n }\n}<\/code><\/pre>\n\n\n\nsudo ln -s \/etc\/nginx\/sites-available\/myapp \/etc\/nginx\/sites-enabled\/\nsudo rm \/etc\/nginx\/sites-enabled\/default\nsudo nginx -t\nsudo systemctl reload nginx<\/code><\/pre>\n\n\n\nStep 6: Turn on the firewall<\/h3>\n\n\n\n