Nginx 的跳转有三种写法，即 rewrite、return、error_page

server {
    listen 80;
    server_name domain.com;
    rewrite ^(.*) https://$server_name$1 permanent;
}
server {
    listen 443 ssl;
    server_name domain.com;
    ssl on;
    # other
}

server {
    listen 80;
    server_name domain.com;
    return 301 https://$server_name$request_uri;
}
server {
    listen 443 ssl;
    server_name domain.com;
    ssl on;
    # other
}

非常规手段，即利用 497 状态码。

当此虚拟机只允许 HTTPS 来访问时，用 HTTP 访问会让 Nginx 报 497 错误，然后利用 error_page 将链接重定向至 HTTPS 上，即

server {
    listen 443 ssl;
    listen 80;
    server_name domain.com;
    ssl on;
    # other
    error_page 497 https://$server_name$request_uri;
}

当然 497 一般用于非标准端口上，譬如 9443 端口默认使用使用 ssl

server {
    listen 9443 ssl;
    server_name domain.com;
    # other
    error_page 497 https://$server_name$server_port$request_uri;
}