Free HTTPS certificate with CentOS 7 , Nginx and Let’s Encrypt

In modern web deployment, configuring multiple sites with Nginx—whether using different domains or subdomains—and enabling HTTPS has become a standard best practice. HTTPS not only enhances the security and trustworthiness of your websites but also contributes positively to SEO rankings.

This guide walks you through a full example of hosting two static sites on yourdomain.com and its subdomain tgame.yourdomain.com using Nginx and Certbot on CentOS 7. Whether you’re a beginner webmaster or a DevOps engineer, this tutorial will help you implement a free HTTPS solution with automated certificate management using Let’s Encrypt.

🧾 1. Environment Requirements

Component	Description
OS	CentOS 7 or later
Web Server	Nginx
HTTPS Certificate	Let’s Encrypt (via Certbot)
Domains	`yourdomain.com`, `tgame.yourdomain.com`
Prerequisites	Valid domains with DNS correctly pointing to your public server IP

🛠️ 2. Install Required Packages

Step 1: Install EPEL and Nginx

sudo yum install epel-release -y
sudo yum install nginx -y
sudo systemctl start nginx
sudo systemctl enable nginx

sudo yum install epel-release -y
sudo yum install nginx -y
sudo systemctl start nginx
sudo systemctl enable nginx

Step 2: Install Certbot and Nginx Plugin

sudo yum install certbot python2-certbot-nginx -y

sudo yum install certbot python2-certbot-nginx -y

📁 3. Create Website Root Directories (Optional but Recommended)

To better organize content for multiple sites, create separate directories for each domain:

sudo mkdir -p /var/www/yourdomain.com/html
sudo mkdir -p /var/www/tgame.yourdomain.com/html
sudo chown -R nginx:nginx /var/www

sudo mkdir -p /var/www/yourdomain.com/html
sudo mkdir -p /var/www/tgame.yourdomain.com/html
sudo chown -R nginx:nginx /var/www

You can now place your index.html or other static content in the respective folders.

⚙️ 4. Configure Nginx Virtual Hosts

Step 1: Create Config for Main Domain

File: /etc/nginx/conf.d/yourdomain.com.conf

server {
    listen 80;
    server_name yourdomain.com www.yourdomain.com;

    root /var/www/yourdomain.com/html;
    index index.html;

    location / {
        try_files $uri $uri/ =404;
    }
}

server {
    listen 80;
    server_name yourdomain.com www.yourdomain.com;

    root /var/www/yourdomain.com/html;
    index index.html;

    location / {
        try_files $uri $uri/ =404;
    }
}

Step 2: Create Config for Subdomain

File: /etc/nginx/conf.d/tgame.yourdomain.com.conf

server {
    listen 80;
    server_name tgame.yourdomain.com;

    root /var/www/tgame.yourdomain.com/html;
    index index.html;

    location / {
        try_files $uri $uri/ =404;
    }
}

server {
    listen 80;
    server_name tgame.yourdomain.com;

    root /var/www/tgame.yourdomain.com/html;
    index index.html;

    location / {
        try_files $uri $uri/ =404;
    }
}

Step 3: Test and Reload Nginx

sudo nginx -t
sudo systemctl reload nginx

sudo nginx -t
sudo systemctl reload nginx

🌐 5. Set Up DNS Records

Type	Name	Value (Server IP)
A	@	123.123.123.123
A	www	123.123.123.123
A	tgame	123.123.123.123

Tips:

Use dig tgame.yourdomain.com +short or ping to verify DNS resolution.
If using Cloudflare, disable proxy (make icon gray) for A records to ensure Let’s Encrypt validation can succeed.

🔐 6. Obtain and Configure HTTPS Certificates

Use Certbot to automatically issue certificates and update your Nginx config.

Issue for Individual Sites

sudo certbot -nginx -d yourdomain.com -d www.yourdomain.com
sudo certbot -nginx -d tgame.yourdomain.com

sudo certbot -nginx -d yourdomain.com -d www.yourdomain.com
sudo certbot -nginx -d tgame.yourdomain.com

Recommended: Issue for Multiple Domains at Once

sudo certbot -nginx \
  -d yourdomain.com \
  -d www.yourdomain.com \
  -d tgame.yourdomain.com

sudo certbot -nginx \
  -d yourdomain.com \
  -d www.yourdomain.com \
  -d tgame.yourdomain.com

Certbot will automatically:

Validate domain ownership
Issue a 90-day certificate
Update your Nginx configs for HTTPS
Add HTTP → HTTPS permanent redirects (301)

🔁 7. Test Auto-Renewal

Let’s Encrypt certificates are valid for 90 days. Certbot sets up auto-renewal using cron or systemd. Test it manually with:

sudo certbot renew -dry-run

sudo certbot renew -dry-run

📊 8. Verify Deployment

Open your browser and check:

https://yourdomain.com
https://www.yourdomain.com
https://tgame.yourdomain.com

You should see your site content and a secure HTTPS (green padlock) icon.

❗ 9. Common Issues & Fixes

Problem	Likely Cause	Solution
NXDOMAIN error	DNS not resolved	Check DNS records; wait for propagation
403 Forbidden	Incorrect permissions or missing files	Check ownership and presence of `index.html`
Certificate failure	Port 80/443 blocked by firewall/proxy	Open required ports or stop conflicting services
HTTPS error page	Browser cache or Nginx not reloaded	Clear cache, test config with `nginx -t`, reload