Nginx configuration for HTTP to HTTPS redirect - force HTTPS access

Preface

Recently, several projects went live, and corresponding SSL certificates were applied for. However, I discovered an issue: when users type the domain directly in the browser, the browser defaults to the HTTP site, but our website only supports HTTPS access, so it becomes inaccessible.

You can actually redirect all access to HTTPS in the global nginx configuration, but some sites on the server provide HTTP services, so each site needs to be configured separately.

Based on the information found through search engines, this article summarizes three configuration methods. If needed, you can choose the one that suits you best.

nginx's Rewrite Method

Description

This should be the most straightforward method everyone thinks of: simply redirect all HTTP requests to HTTPS using rewrite rules.

Configuration

server {
	listen	192.168.1.111:80;
	server_name	test.com;
	
	rewrite ^(.*)$	https://$host$1	permanent;
}

Once this virtual host is set up, all requests to http://test.com will be rewritten to https://test.com.

nginx's 497 Status Code

Error Code 497

497 - normal request was sent to HTTPS

Explanation: This error code occurs when a virtual site only allows HTTPS access, but an attempt is made to access it via HTTP. In this case, Nginx returns the 497 error code.

Instructions

Use the error_page directive to redirect links with a 497 status code to the domain https://test.com.

Configuration

server {
	listen       192.168.1.11:443;	# SSL port
	listen       192.168.1.11:80;	# Users are accustomed to accessing via http, so port 80 is added. Later, through the 497 status code, it automatically redirects to port 443.
	server_name  test.com;
	# Enable SSL support for a server block {......}
	ssl                  on;
	# Specify the certificate file in PEM format
	ssl_certificate      /etc/nginx/test.pem; 
	# Specify the private key file in PEM format
	ssl_certificate_key  /etc/nginx/test.key;
	
	# Redirect http requests to https requests
	error_page 497	https://$host$uri?$args;
}

index.html Refresh Method

Explanation

Both of the above methods require server-side computation and will consume server resources. The page refresh method was learned from Baidu.
Let's use curl to access baidu.com to see how Baidu implements the redirect from baidu.com to www.baidu.com.

As you can see, Baidu cleverly uses the meta refresh to redirect baidu.com to www.baidu.com. Therefore, we can also create an index.html file in the virtual host path for http://test.com, with content that redirects from http to https.

index.html Web Content

<html>
<meta http-equiv="refresh" content="0;url=https://test.com/">
</html>

Site Configuration

Add an HTTP site configuration in the server configuration to provide access to the index.html file mentioned earlier.

server {
	listen 80;
	server_name	test.com;
	
	location / {
                #index.html is placed in the root directory listened by the virtual host
		root /srv/www/http.test.com/;
	}
        #Redirect 404 page to the https homepage
	error_page	404	https://test.com/;
}

References

https://blog.csdn.net/wzy_1988/article/details/8549290