基于值头的平衡器nginx

如何解决基于值头的平衡器nginx

我是 Nginx 新手，想请教一下。我需要为平衡器编写以下逻辑。请求转到公共地址 gate.mysite.com，然后代理到四个外部服务器 remote[1-4].server.com 之一。 如果请求包含带有某个数字的标头“X-Stamp”，则请求将路由到服务器，其数量使用公式 (X-Stamp mod 4)+1 计算。如果没有标题“X-Stamp”，则为循环。此外，还有以下路由规则：

gate1.mysite.com -> remote1.server.com
gate2.mysite.com -> remote2.server.com
gate3.mysite.com -> remote3.server.com
gate4.mysite.com -> remote4.server.com

我使用 Nginx openresty 编写了这样的配置。

http {
upstream host1 {
        server remote1.server.com:443;
}
upstream host2 {
        server remote2.server.com:443;
}
upstream host3 {
        server remote3.server.com:443;
}
upstream host4 {
        server remote4.server.com:443;
}
upstream all {
        server remote1.server.com:443;
        server remote2.server.com:443;
        server remote3.server.com:443;
        server remote4.server.com:443;
}
server {
        listen 80;
        server_name _;
        return 301 https://$host$request_uri;
}
server {
        listen   443 ssl;
        server_name gate.mysite.com;
        ...
        location / {
                set $num_header_glob '';
                rewrite_by_lua_block {
                        --reading request headers
                        local req_headers = ngx.req.get_headers()
                        local num_header  = ""
                        -- checking an a header value to determine target uri
                        if req_headers["X-Stamp"] then
                                num_header = ((req_headers["X-Stamp"])%4)+1
                        else
                                -- default path if not header found
                                num_header = "5"
                        end
                        ngx.log(ngx.NOTICE,string.format("resolved num_header: %s",num_header))
                        ngx.var.num_header_glob = num_header
                }
            proxy_pass https://$target_uri;
        }
        
}
map $num_header_glob $target_uri {
                "1" "host1";
                "2" "host2";
                "3" "host3";
                "4" "host4";
                "5" "all";
                }

}
server {
        listen   443 ssl;
        server_name gate1.mysite.com;
        ...
        location / {
                proxy_pass https://host1;
        }
}
server {
        listen   443 ssl;
        server_name gate2.mysite.com;
        ...
        location / {
                proxy_pass https://host2;
        }
}
server {
        listen   443 ssl;
        server_name gate3.mysite.com;
        ...
        location / {
                proxy_pass https://host3;
        }
}
server {
        listen   443 ssl;
        server_name gate4.mysite.com;
        ...
        location / {
                proxy_pass https://host4;
        }
}
}

但是我需要补充以下条件——如果我在响应中收到一个HTTP-status 307，我需要替换传输给客户端的HTTP头位置值

"remote1.server.com" to "gate1.mysite.com"
"remote2.server.com" to "gate2.mysite.com"
"remote3.server.com" to "gate3.mysite.com"
"remote4.server.com" to "gate4.mysite.com"

如何实现？

解决方法

您正在寻找的是 header_filter 阶段。类似的东西：

header_filter_by_lua_block {
  if ngx.status == 307 then
    ngx.header["Location"] = (ngx.header["Location"] or ""):gsub("://remote(%d).server.com","://gate%1.mysite.com")
  end
}