nginx proxy_pass同时支持http/https的小技巧

个人学习笔记，谢绝转载！！！

原文：https://www.cnblogs.com/wshenjin/p/13183929.html

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nginx在配置http/https代理，最开始比较麻烦的写法：

upstream example
{
        server 1.1.1.1:80;
        server 2.2.2.2:80 backup;
}

upstream example_https
{
        server 1.1.1.1:443;
        server 2.2.2.2:443 backup;
}

server
{
    listen       80;
    server_name  www.example.com;
    index index.html index.htm index.php;
    root /data/web/webclose;
    location / {
        proxy_pass  http://example;
        expires off;
        proxy_redirect     off;
        proxy_set_header   Host             $host;
        proxy_set_header   X-Real-IP        $remote_addr;
        proxy_set_header   X-Forwarded-For  $proxy_add_x_forwarded_for;
    }
    access_log  /data/logs/$host.log  access;
}

server
{
    listen       443 ssl;
    server_name  www.example.com;
    root /data/web/webclose;
    include ssl_example.conf;
    location / {
        proxy_pass  https://example_https;
        expires off;
        proxy_redirect     off;
        proxy_set_header   Host             $host;
        proxy_set_header   X-Real-IP        $remote_addr;
        proxy_set_header   X-Forwarded-For  $proxy_add_x_forwarded_for;
    }
    access_log  /data/logs/$host.log  access;
}

这种写法比较麻烦，要写两份。
因此投机取巧换个写法：

upstream example_http
{
        server 1.1.1.1:80;
        server 2.2.2.2:80 backup;
}

upstream example_https
{
        server 1.1.1.1:443;
        server 2.2.2.2:443 backup;
}

server
{
    listen       80;
    listen       443 ssl;
    server_name  www.example.com;
    index index.html index.htm index.php;
    root /data/web/webclose;
    include ssl_example.conf;
    location / {
        proxy_pass  $scheme://example_$scheme;
        expires off;
        proxy_redirect     off;
        proxy_set_header   Host             $host;
        proxy_set_header   X-Real-IP        $remote_addr;
        proxy_set_header   X-Forwarded-For  $proxy_add_x_forwarded_for;
    }
    access_log  /data/logs/$host.log  access;
}

可以充分利用nginx的变量简化配置的编写。