From Localhost to the Internet: Deploying a .NET API to a Linux VPS

Localhost is comfortable. It's fast, it's safe, and it never goes down. But it has one fatal flaw — nobody else can access it.

If you want your app to be real, it needs to live on a real server. That means learning Linux, Nginx, systemd, and SSL certificates — topics many .NET developers avoid because they feel like "DevOps stuff." But here's the truth: deploying your own app is one of the most confidence-building things you can do as a developer. DNS, HTTP, ports, processes — all abstract concepts until you configure them yourself.

This article covers exactly how I deployed my .NET 10 Chat API to a Ubuntu 24 VPS — from a zip file to a live HTTPS endpoint.

The target architecture

Nginx sits in front of everything. It handles SSL, accepts public traffic, and forwards requests to the .NET API running locally. The API never exposes itself directly to the internet — Nginx is the only public face.

Step 1 — Publish the API

First, publish the API as a self-contained release build:

cd ChatApp.API
dotnet publish -c Release -o ./publish

Then zip it for easy upload:

# PowerShell
Compress-Archive -Path ./publish/* -DestinationPath ./chatapp-api.zip

Step 2 — Upload to the server

scp ./chatapp-api.zip root@YOUR_VPS_IP:/var/www/chatapp-api/

Step 3 — Install .NET 10 on Ubuntu

Ubuntu's package manager doesn't always have the latest .NET version. Use the official install script:

wget https://dot.net/v1/dotnet-install.sh
chmod +x dotnet-install.sh
./dotnet-install.sh --version latest

Then add .NET to the PATH — and here's the critical detail most tutorials miss. The order matters:

export DOTNET_ROOT=$HOME/.dotnet
export PATH=$HOME/.dotnet:$HOME/.dotnet/tools:$PATH

Notice .dotnet comes before the rest of $PATH. If the system has .NET 8 installed globally and you put your .NET 10 path at the end, the system version wins. PATH is first-match wins.

Step 4 — Extract and test

cd /var/www/chatapp-api
unzip chatapp-api.zip
dotnet ChatApp.API.dll --urls "http://0.0.0.0:5246"

When you see that output, the hard part is done.

Step 5 — systemd service

Running dotnet manually works — until you close the terminal. For a real server, you need the process to run forever, survive reboots, and restart automatically if it crashes. That's what systemd is for.

nano /etc/systemd/system/chatapp-api.service

[Unit]
Description=Logic Dynamics Chat API
After=network.target

[Service]
WorkingDirectory=/var/www/chatapp-api
ExecStart=/root/.dotnet/dotnet ChatApp.API.dll --urls "http://0.0.0.0:5246"
Restart=always
RestartSec=10
Environment=ASPNETCORE_ENVIRONMENT=Production
Environment=DOTNET_ROOT=/root/.dotnet
Environment=PATH=/root/.dotnet:/root/.dotnet/tools:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin

[Install]
WantedBy=multi-user.target

systemctl daemon-reload
systemctl enable chatapp-api   # auto-start on boot
systemctl start chatapp-api
systemctl status chatapp-api

Step 6 — Nginx reverse proxy

server {
    listen 80;
    server_name chat-api.logicdynamics.net;

    location / {
        proxy_pass http://localhost:5246;
        proxy_http_version 1.1;

        # Critical for SignalR WebSocket upgrade
        proxy_set_header Upgrade $http_upgrade;
        proxy_set_header Connection "upgrade";

        proxy_set_header Host $host;
        proxy_cache_bypass $http_upgrade;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
    }
}

ln -s /etc/nginx/sites-available/chatapp-api /etc/nginx/sites-enabled/
nginx -t        # test config — never skip this
systemctl reload nginx

Step 7 — DNS record

On Hostinger, add a simple A record pointing your subdomain to your VPS IP with a TTL of 300 seconds. Changes propagate in about 5 minutes.

Step 8 — SSL certificate

Free SSL via Let's Encrypt. Certbot handles everything — certificate request, Nginx config update, and automatic renewal:

apt install certbot python3-certbot-nginx -y
certbot --nginx -d chat-api.logicdynamics.net

Certbot automatically updates the Nginx config to listen on port 443 and redirect HTTP to HTTPS. It also sets up a cron job to renew the certificate before it expires.

The update workflow

When you push code changes, the full deployment process takes under two minutes:

# 1. Publish locally
dotnet publish -c Release -o ./publish
Compress-Archive -Path ./publish/* -DestinationPath ./chatapp-api.zip

# 2. Upload
scp ./chatapp-api.zip root@YOUR_VPS_IP:/var/www/chatapp-api/

# 3. On the server
ssh root@YOUR_VPS_IP
cd /var/www/chatapp-api
unzip -o chatapp-api.zip   # -o flag overwrites existing files
systemctl restart chatapp-api

What I learned

• Linux is just another tool. There are only about 15 commands you need for basic VPS management. Once you've done it once, it becomes muscle memory.
• systemd is your friend. journalctl -u chatapp-api -f gives you live logs — essential for debugging production issues.
• Nginx is a proxy powerhouse. One instance can front multiple APIs, handle SSL for all of them, and add rate limiting and caching.
• SSL is free and easy. There's no excuse for HTTP in 2026. Certbot makes it a two-minute job.

The full source code including deployment config is at github.com/LogicDynamics/ChatApp.