Nginx配置疑问：HTTPS无WWW域名未跳转至WWW及重定向循环问题

Hey there, let's sort out that frustrating redirect loop and get your non-www HTTPS traffic properly pointing to https://www.example.com for consistent SEO tracking. Here's the breakdown of the issue and step-by-step fixes:

First, Confirm Your SSL Certificate #

Make sure your SSL certificate covers both example.com and www.example.com (either a SAN certificate or wildcard certificate). If it doesn't, visitors will hit certificate errors when accessing https://example.com before the redirect even happens—this is a critical prerequisite.

Update Your Server Configuration (Nginx Example) #

The redirect loop usually happens because you tried handling both non-www and www HTTPS traffic in the same server block, making the redirect rule trigger even for valid www requests. Split them into separate blocks for precise control:

1. HTTP Server Block (Catch All Plain HTTP Traffic)
   This handles all unencrypted requests (both non-www and www) and redirects them directly to the HTTPS www version:

   server {
       listen 80;
       server_name example.com www.example.com;
       return 301 https://www.example.com$request_uri;
   }
   

2. HTTPS Server Block (Non-WWW Redirect)
   This specifically targets https://example.com and redirects it to the www variant. Use the same SSL certificate as your main site:

   server {
       listen 443 ssl;
       server_name example.com;
   
       # Copy your SSL certificate config here
       ssl_certificate /path/to/your/fullchain.pem;
       ssl_certificate_key /path/to/your/privkey.pem;
       # Include shared SSL settings (like protocols/ciphers) if you have them
       # include /etc/nginx/ssl-params.conf;
   
       return 301 https://www.example.com$request_uri;
   }
   

3. HTTPS Server Block (Main WWW Site)
   This is your existing working configuration for https://www.example.com—keep all your site's root, location, and application logic here:

   server {
       listen 443 ssl;
       server_name www.example.com;
   
       # Same SSL certificate config as above
       ssl_certificate /path/to/your/fullchain.pem;
       ssl_certificate_key /path/to/your/privkey.pem;
       # include /etc/nginx/ssl-params.conf;
   
       # Your site's core configuration
       root /var/www/your-site;
       index index.html index.php;
   
       # Add your location blocks, proxy settings, etc. here
       location / {
           try_files $uri $uri/ =404;
       }
   }
   

Test the Fix #

After updating the config, reload your server to apply changes:

sudo nginx -s reload

Verify the redirect works with this curl command:

curl -I https://example.com

You should see a 301 Moved Permanently response with Location: https://www.example.com/ (or the specific path you tested).

Why This Eliminates the Loop #

By splitting HTTPS traffic into two separate server blocks, we ensure the redirect rule only runs when the request is for example.com (non-www). The main www server block handles valid https://www.example.com traffic without triggering any redirects, breaking the loop entirely.

内容的提问来源于stack exchange，提问作者user500963