nginx 1.6 cache objects depend on proxy_cache_key,such as

nginx 1.6的缓存对象取决于proxy_cache_key的设置,比如

proxy_cache_key $uri$is_args$args;

nginx 1.7 cache objects depend on proxy_cache_key and VARY Header

nginx 1.7的缓存对象取决于proxy_cache_key 和 服务器返回的VARY头的内容
Changes with nginx 1.7.7 28 Oct 2014

*) Change: now nginx takes into account the "Vary" header line in a
backend response while caching.

If the upstream server reponsed this header: “Vary: Accept-Encoding”, cache object of the same url may save many copys depend on the different request headers: “Accept-Encoding”, in nginx 1.7 or above versions.

假如,你的upstream服务器返回了这样的header: “Vary: Accept-Encoding”,

相同一个url的缓存对象会基于请求header里边的”Accept-Encoding”的不同值 保存为许多份不同的副本,这个特性起于nginx1.7 版本

In this case, purge cache may failed, cause you don’t how many cache objects with “Accept-Encoding” headers

在这种情况下,清理缓存通常会失败,因为你不知道有多少的缓存对象有着哪些对应的”Accept-Encoding” headers

You have 2 choices to fix this problem:

你有两种选择来对付这个问题:

1. Rewrite the reuqest header “Accept-Encoding” in the front proxy serve

在最前端的代理服务器 重写请求的header: “Accept-Encoding”

set $compress "none";
if ($http_accept_encoding ~* "gzip|deflate|compress") {set $compress "gzip,deflate";}
proxy_set_header Accept-Encoding $compress;

2. Ignore the response header “Vary” in the middle cache server

或者在中间层的cache服务器 忽略掉服务器返回的header “Vary”
proxy_ignore_headers  Vary;

在这里, “Vary: Accept-Encoding”, 只是一个非常常见的举例,实际上你的后端源站可能会返回特异的Vary Header.

nginx 里边在server_name 或者 if的时候会用到一些简单的正则,实际上跟普通的正则会有些不同,简单举2个例子

1. server_name *.4os.org
它其实能匹配 test.www.4os.org, 它能匹配多级,这个需要注意下

2. 普通正则里边的 \s* 这里的* 表示 匹配前面的子表达式 零次 或 多次
而nginx 里边的* 一般都是表示存在的东西,这个是概念上的不同

Adds the specified field to a response header provided that the response code equals 200, 201 (1.3.10), 204, 206, 301, 302, 303, 304, 307 (1.1.16, 1.0.13), or 308 (1.13.0). The value can contain variables.

There could be several add_header directives. These directives are inherited from the previous level if and only if there are no add_header directives defined on the current level.

add_header指令可以从上一级继承  当且仅当 当前级别没有add_header指令

If the always parameter is specified (1.7.5), the header field will be added regardless of the response code.

在全局配置加了个需要使用的header, 现在假如在某个location 或者 server 也需要add_header,则会覆盖掉全局配置的

http {… add_header http-global ‘123’;…}

server {… add_header server-conf ‘321’;…}

则 这个server 是看不到 http-global: 123  这个header的,需要注意

其实,proxy_set_header 也是完全相同的情况

proxy_set_header Host $proxy_host;

proxy_set_header Connection close;

Allows redefining or appending fields to the request header passed to the proxied server. The value can contain text, variables, and their combinations. These directives are inherited from the previous level if and only if there are no proxy_set_header directives defined on the current level. By default, only two fields are redefined:

nginx有时候希望嵌套的处理error_page
比如 location / {
error_page 404 @fetch
}

location @fetch {
error_page 404 @fetch2
proxy_pass http://backend1/one/;
}
location @fetch2 {
proxy_pass http://backend2/two/;
return 200 “xxx”;
}

这是个简单的例子,如果需要实现功能需要两个参数: proxy_intercept_errors on; recursive_error_pages on;
syntax: recursive_error_pages on | off;
default:
recursive_error_pages off;
context: http, server, location
Enables or disables doing several redirects using the error_page directive. The number of such redirects is limited.

syntax: proxy_intercept_errors on | off;
default:
proxy_intercept_errors off;
context: http, server, location
Determines whether proxied responses with codes greater than or equal to 300 should be passed to a client or be redirected to nginx for processing with the error_page directive.