我有一个API服务器的Nginx代理. API有时会设置缓存控制标头.如果API没有设置缓存控件,我希望Nginx覆盖它.
我怎么做？
我想我想做这样的事情,但它不起作用.
location /api {
if ($sent_http_cache_control !~* "max-age=90") {
add_header Cache-Control no-store;
add_header Cache-Control no-cache;
add_header Cache-Control private;
}
proxy_pass $apiPath;
}
如果在这里,则不能使用,因为如果作为重写模块的一部分,在请求处理的早期阶段进行评估,则在调用proxy_pass并从上游服务器返回标头之前.
解决问题的一种方法是使用map指令.使用map定义的变量仅在使用时进行评估,这正是您在此处所需的.概略地说,在这种情况下您的配置如下所示：
# When the $custom_cache_control variable is being addressed
# look up the value of the Cache-Control header held in
# the $upstream_http_cache_control variable
map $upstream_http_cache_control $custom_cache_control {
# Set the $custom_cache_control variable with the original
# response header from the upstream server if it consists
# of at least one character (. is a regular expression)
"~." $upstream_http_cache_control;
# Otherwise set it with this value
default "no-store,no-cache,private";
}
server {
...
location /api {
proxy_pass $apiPath;
# Prevent sending the original response header to the client
# in order to avoid unnecessary duplication
proxy_hide_header Cache-Control;
# Evaluate and send the right header
add_header Cache-Control $custom_cache_control;
}
...
}
