背景介紹

上篇介紹了利用Nginx反向代理實現負載均衡，本文詳細講述Nginx下的幾種負載均衡策略。

輪詢

輪詢，顧名思義，就是輪流請求，基于上篇文章的介紹，我們將負載均衡策略聚焦于default.conf文件的upstream。

upstream backend {server web02:80;server web03:80; }

在瀏覽器中對localhost:8080連續發出請求，根據nginx請求日志可以看出web02與web03訪問的次數是相同的。

web01 | 172.24.0.1 - - [26/Jun/2019:10:03:06 +0000] "GET / HTTP/1.1" 304 0 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36" "-" web02 | 172.24.0.3 - - [26/Jun/2019:10:03:06 +0000] "GET / HTTP/1.0" 304 0 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36" "-" web01 | 172.24.0.1 - - [26/Jun/2019:10:03:07 +0000] "GET / HTTP/1.1" 304 0 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36" "-" web03 | 172.24.0.3 - - [26/Jun/2019:10:03:07 +0000] "GET / HTTP/1.0" 304 0 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36" "-" web02 | 172.24.0.3 - - [26/Jun/2019:10:05:25 +0000] "GET / HTTP/1.0" 304 0 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36" "-" web01 | 172.24.0.1 - - [26/Jun/2019:10:05:25 +0000] "GET / HTTP/1.1" 304 0 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36" "-" web03 | 172.24.0.3 - - [26/Jun/2019:10:05:26 +0000] "GET / HTTP/1.0" 304 0 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36" "-" web01 | 172.24.0.1 - - [26/Jun/2019:10:05:26 +0000] "GET / HTTP/1.1" 304 0 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36" "-" web02 | 172.24.0.3 - - [26/Jun/2019:10:05:27 +0000] "GET / HTTP/1.0" 304 0 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36" "-" web01 | 172.24.0.1 - - [26/Jun/2019:10:05:27 +0000] "GET / HTTP/1.1" 304 0 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36" "-" web01 | 172.24.0.1 - - [26/Jun/2019:10:05:27 +0000] "GET / HTTP/1.1" 304 0 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36" "-" web03 | 172.24.0.3 - - [26/Jun/2019:10:05:27 +0000] "GET / HTTP/1.0" 304 0 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36" "-"

加權輪詢

加權輪詢是指基于上文中的輪詢，加上一定的權重，使得某個服務器被轉發的次數更多一些，加權通過在IP后方拼接weight實現。

upstream backend {server web02:80 weight=5;server web03:80 weight=1; }

weight值越大，所分配的請求就越多，根據nginx的請求日志可以看出web02被訪問了8次，web03被訪問了兩次。

web01 | 172.24.0.1 - - [26/Jun/2019:14:48:13 +0000] "GET / HTTP/1.1" 304 0 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36" "-" web02 | 172.24.0.3 - - [26/Jun/2019:14:48:13 +0000] "GET / HTTP/1.0" 304 0 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36" "-" web02 | 172.24.0.3 - - [26/Jun/2019:14:48:16 +0000] "GET / HTTP/1.0" 304 0 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36" "-" web01 | 172.24.0.1 - - [26/Jun/2019:14:48:16 +0000] "GET / HTTP/1.1" 304 0 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36" "-" web01 | 172.24.0.1 - - [26/Jun/2019:14:48:16 +0000] "GET / HTTP/1.1" 304 0 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36" "-" web02 | 172.24.0.3 - - [26/Jun/2019:14:48:16 +0000] "GET / HTTP/1.0" 304 0 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36" "-" web01 | 172.24.0.1 - - [26/Jun/2019:14:48:17 +0000] "GET / HTTP/1.1" 304 0 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36" "-" web03 | 172.24.0.3 - - [26/Jun/2019:14:48:17 +0000] "GET / HTTP/1.0" 304 0 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36" "-" web01 | 172.24.0.1 - - [26/Jun/2019:14:48:17 +0000] "GET / HTTP/1.1" 304 0 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36" "-" web02 | 172.24.0.3 - - [26/Jun/2019:14:48:17 +0000] "GET / HTTP/1.0" 304 0 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36" "-" web02 | 172.24.0.3 - - [26/Jun/2019:14:48:18 +0000] "GET / HTTP/1.0" 304 0 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36" "-" web01 | 172.24.0.1 - - [26/Jun/2019:14:48:18 +0000] "GET / HTTP/1.1" 304 0 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36" "-" web01 | 172.24.0.1 - - [26/Jun/2019:14:48:19 +0000] "GET / HTTP/1.1" 304 0 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36" "-" web02 | 172.24.0.3 - - [26/Jun/2019:14:48:19 +0000] "GET / HTTP/1.0" 304 0 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36" "-" web01 | 172.24.0.1 - - [26/Jun/2019:14:48:19 +0000] "GET / HTTP/1.1" 304 0 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36" "-" web02 | 172.24.0.3 - - [26/Jun/2019:14:48:19 +0000] "GET / HTTP/1.0" 304 0 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36" "-" web01 | 172.24.0.1 - - [26/Jun/2019:14:48:20 +0000] "GET / HTTP/1.1" 304 0 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36" "-" web02 | 172.24.0.3 - - [26/Jun/2019:14:48:20 +0000] "GET / HTTP/1.0" 304 0 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36" "-" web03 | 172.24.0.3 - - [26/Jun/2019:14:48:20 +0000] "GET / HTTP/1.0" 304 0 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36" "-" web01 | 172.24.0.1 - - [26/Jun/2019:14:48:20 +0000] "GET / HTTP/1.1" 304 0 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36" "-"

ip_hash

如果一個客戶端的請求可能被轉發到任何一臺服務器，可能會導致每臺服務器都緩存了該客戶端的信息，比較浪費資源，ip_hash作用就是通過客戶端IP的前三個部分計算出key，以便將同一個客戶端的請求轉發到指定的服務器中，配置的方法比較簡單，只需要在upstream上方加一行代碼即可。

upstream backend {ip_hash;server web02:80;server web03:80; }

重復請求了5次，通過日志看出請求一直被鎖定在了web03上。

web01 | 172.24.0.1 - - [27/Jun/2019:11:48:15 +0000] "GET / HTTP/1.1" 304 0 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36" "-" web03 | 172.24.0.2 - - [27/Jun/2019:11:48:15 +0000] "GET / HTTP/1.0" 304 0 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36" "172.24.0.1" web01 | 172.24.0.1 - - [27/Jun/2019:11:48:22 +0000] "GET / HTTP/1.1" 304 0 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36" "-" web03 | 172.24.0.2 - - [27/Jun/2019:11:48:22 +0000] "GET / HTTP/1.0" 304 0 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36" "172.24.0.1" web03 | 172.24.0.2 - - [27/Jun/2019:11:48:23 +0000] "GET / HTTP/1.0" 304 0 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36" "172.24.0.1" web01 | 172.24.0.1 - - [27/Jun/2019:11:48:23 +0000] "GET / HTTP/1.1" 304 0 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36" "-" web03 | 172.24.0.2 - - [27/Jun/2019:11:48:24 +0000] "GET / HTTP/1.0" 304 0 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36" "172.24.0.1" web01 | 172.24.0.1 - - [27/Jun/2019:11:48:24 +0000] "GET / HTTP/1.1" 304 0 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36" "-" web01 | 172.24.0.1 - - [27/Jun/2019:11:48:24 +0000] "GET / HTTP/1.1" 304 0 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36" "-" web03 | 172.24.0.2 - - [27/Jun/2019:11:48:24 +0000] "GET / HTTP/1.0" 304 0 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36" "172.24.0.1"

url_hash

這種模式是將url進行哈希，然后定位到具體的某一臺服務器，相同的url永遠會被轉發到同一臺服務器上。

upstream backend {hash $request_uri;server web02:80;server web03:80; }

通過瀏覽器訪問兩次http://localhost:8080，通過日志可以看到轉發被固定在了web03。

web01 | 172.24.0.1 - - [27/Jun/2019:11:58:31 +0000] "GET / HTTP/1.1" 304 0 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36" "-" web03 | 172.24.0.4 - - [27/Jun/2019:11:58:31 +0000] "GET / HTTP/1.0" 304 0 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36" "-" web03 | 172.24.0.4 - - [27/Jun/2019:11:58:38 +0000] "GET / HTTP/1.0" 304 0 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36" "-" web01 | 172.24.0.1 - - [27/Jun/2019:11:58:38 +0000] "GET / HTTP/1.1" 304 0 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36" "-"

在鏈接后面拼接一些參數，就可以看到轉發發生了變化，固定在了web02，隨著參數的變化，請求也會采用輪詢的方式轉發給服務器，但使用過的url再訪問就不會再變化了。

web02 | 172.24.0.4 - - [27/Jun/2019:11:59:54 +0000] "GET /?a=1 HTTP/1.0" 304 0 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36" "-" web01 | 172.24.0.1 - - [27/Jun/2019:11:59:54 +0000] "GET /?a=1 HTTP/1.1" 304 0 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36" "-" web02 | 172.24.0.4 - - [27/Jun/2019:11:59:55 +0000] "GET /?a=1 HTTP/1.0" 304 0 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36" "-" web01 | 172.24.0.1 - - [27/Jun/2019:11:59:55 +0000] "GET /?a=1 HTTP/1.1" 304 0 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36" "-"

轉載于:https://www.cnblogs.com/enochzzg/p/11099354.html

總結

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