Nginx upstream(Load Balance)

Load Balance 手段

Nginx可用來做正向(Forward)、反向(Reverse)代理
針對網址的流水號 or 特定參數，做切割分派
動靜態資料分流
HTTP 1.1 Long polling(長握手)，改用 301 將 Connection keep 到目標 server 上，別綁在 proxy server 身上

正向代理

server {
    listen 8080;
    resolver 168.95.1.1;
    access_log off;
    location / {
        proxy_pass http://$host$request_uri;
        proxy_set_header Host $http_host;
        proxy_buffers 256 4k;
    }
}

反向代理

round-robin(Default) 照順序輪，會跳過 Down 掉的 server

http {
    upstream myapp1 {
        server srv1.example.com;
        server srv2.example.com;
    }
    server {
     listen 80;
        location / {

      # 傳遞真實IP到後端
      #proxy_set_header Host $http_host;
      #proxy_set_header X-Real-IP $remote_addr;
      #proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
      proxy_pass http://myapp1;
  }
 }
}

Weight 權重

upstream myapp1 {
    server srv1.example.com weight=10;
    server srv2.example.com;
}

IP-Hash 用IP雜湊分配，可解決 session 問題

upstream myapp1 {
    ip_hash;
    server srv1.example.com;
    server srv2.example.com;
}

Least Connect 最少連線數的 server 優先使用

upstream myapp1 {
    least_conn;
    server srv1.example.com;
    server srv2.example.com;
}

fair（第三方）按後端服務器的回應時間來分配，反映快的優先分配。

upstream myapp1 {
    server server1;
    server server2;
    fair;
}

url_hash（第三方）

按訪問url的hash結果來分配，同 hash 指向同一個服務器，後端服務器為緩存時比較有效。
例：在upstream中加入hash語句，server語句中不能寫入weight等其他的參數

upstream myapp1 {
    server squid1:3128;
    server squid2:3128;
    hash $request_uri;
    hash_method crc32;
}

SSL 1 external port to N internal port (process)

將同一個服務，在內部用不同的 port 分開

upstream upstream_1{
    server 0.0.0.0:1338;
    server 0.0.0.0:1339;
    server 0.0.0.0:1340;
    server 0.0.0.0:1341;
}

server {
    listen 1337 ssl default_server;
    server_name api.mydomain.com;

    ssl_certificate        /var/www/abc/ssl/apache.crt;
    ssl_certificate_key    /var/www/abc/ssl/mydomain.key;
    ssl_client_certificate /var/www/abc/ssl/mydomain.chain.crt;
    ssl_verify_client      off;

    location ~ / {
        proxy_pass https://upstream_1;
    }
}

server 設定

down 暫時不參與負載
weight 數字越大，負載的權重就越大。
max_fails 允許失敗的預設次數，超過時，回傳 proxy_next_upstream 模組定義錯誤
fail_timeout 失敗N次失敗後，暫停的時間。
backup 備援機，在其他 server 忙碌或 down 才會動用

切割網址

server {
    listen 80;
    server_name www.domain.com;
    #ex. /profile/alice
    location ~* /profile/[a-m] {
        proxy_pass http://server0.domain.com;
    }
    #ex. /profile/nick
    location ~* /profile/[n-z] {
        proxy_pass http://server1.domain.com;
    }
    #ex. /profile/3002
    location ~* /profile/[0-9]*[02468]$ {
        proxy_read_timeout 10s;
        proxy_pass http://server0.domain.com;
    }
}

動靜態分流

location / {
    # css, js 靜態文件設置有效期12小時天
    location ~ .*\.(js|css)$ {
        access_log off; #不記入 log
        expires   12h;
    }

    #圖片設置有效期3天
    location ~ .*\.(gif|jpg|jpeg|png|bmp|swf)$ {
        access_log off;
        expires  3d;
    }
}
location ~ \.php$ {
    ...
 proxy_pass xxx;
}
location @proxy {
    ...
}

Long Polling

server {
    listen 80;
    server_name www.my-domain.com;

    location ~* /profile/[a-m] {
        rewrite ^(.*) http://server0.domain.com$1 permanent;
    }

    location ~* /profile/[n-z] {
        rewrite ^(.*) http://server1.domain.com$1 permanent;
    }   
}

參考文獻：
https://my.oschina.net/foreverich/blog/1517128
http://blog.yslin.tw/2012/02/nginx.html

http://blog.yslin.tw/2012/08/nginx-load-balance.html

http://tech.ddvip.com/2009-07/1246936747125436.html
http://www.ha97.com/5194.html
https://www.huaweicloud.com/articles/12528794.html (關於後面有無 / )

官方文獻：
http://nginx.org/en/docs/http/load_balancing.html