Nginx fastcgi_cache权威指南
一、简介
Nginx版本从0.7.48开始,支持了类似Squid的缓存功能。这个缓存是把URL及相关组合当做Key,用Md5算法对Key进行哈希，得到硬盘上对应的哈希目录路径，从而将缓存内容保存在该目录内。
Nginx Web 缓存服务只能为指定URL或状态码设置过期时间，不支持类似Squid的PURGE指令手动清除缓存；但是我们可以通过Nginx的模块ngx_cache_purge清除指定URL的缓存。
- proxy_cache：缓存后端服务器的内容，可能是任何内容，包括静态的和动态，减少了nginx与后端通信的次数，节省了传输时间和后端宽带
- fastcgi_cache：缓存fastcgi生成的内容，很多情况是php生成的动态的内容，少了nginx与php的通信的次数，更减轻了php和数据库(mysql)的压力，这比用memcached之类的缓存要轻松得多
图片来自网络
二、配置
nginx.conf
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fastcgi_cache_path /var/run/nginx-cache levels=1:2 keys_zone=WORDPRESS:100m inactive=60m;fastcgi_cache_key "$scheme$request_method$host$request_uri";fastcgi_cache_use_stale error timeout invalid_header http_500;fastcgi_ignore_headers Cache-Control Expires Set-Cookie;fastcgi_temp_path /tmp/nginx/fcgi/temp; |
vhost配置
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server { server_name example.com www.example.com; access_log /var/log/nginx/example.com.access.log; error_log /var/log/nginx/example.com.error.log; root /var/www/example.com/htdocs; index index.php; set $skip_cache 0; # POST requests and urls with a query string should always go to PHP if ($request_method = POST) { set $skip_cache 1; } if ($query_string != "") { set $skip_cache 1; } # Don't cache uris containing the following segments if ($request_uri ~* "/wp-admin/|/xmlrpc.php|wp-.*.php|/feed/|index.php|sitemap(_index)?.xml") { set $skip_cache 1; } # Don't use the cache for logged in users or recent commenters if ($http_cookie ~* "comment_author|wordpress_[a-f0-9]+|wp-postpass|wordpress_no_cache|wordpress_logged_in") { set $skip_cache 1; } location / { try_files $uri $uri/ /index.php?$args; } location ~ \.php($|/) { try_files $uri =404; include fastcgi_params; fastcgi_split_path_info ^(.+\.php)(/.+)$; fastcgi_param PATH_INFO $fastcgi_path_info; fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name; fastcgi_pass unix:/dev/shm/php-socket; fastcgi_cache_bypass $skip_cache; fastcgi_no_cache $skip_cache; fastcgi_cache WORDPRESS; include fcgi_cache_params; } location ~ /purge(/.*) { fastcgi_cache_purge WORDPRESS "$scheme$request_method$host$1"; } location ~* ^.+\.(ogg|ogv|svg|svgz|eot|otf|woff|mp4|ttf|rss|atom|jpg|jpeg|gif|png|ico|zip|tgz|gz|rar|bz2|doc|xls|exe|ppt|tar|mid|midi|wav|bmp|rtf)$ { access_log off; log_not_found off; expires max; } location = /robots.txt { access_log off; log_not_found off; } location ~ /\. { deny all; access_log off; log_not_found off; }} |
fcgi_cache_params配置
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#include fcgi_cache_params;#fastcgi_cache_valid 200 302 1s;### fcgi-cachefastcgi_cache fcgi;fastcgi_cache_valid 200 302 1s;fastcgi_cache_valid 404 500 502 503 504 0s;fastcgi_cache_valid any 1m;fastcgi_cache_min_uses 1;fastcgi_cache_use_stale error timeout invalid_header http_500 http_503 updating;fastcgi_ignore_headers Cache-Control Expires Set-Cookie;#add_header X-Cache "$upstream_cache_status - $upstream_response_time";fastcgi_cache_key "$scheme$request_method$host$request_uri" |
大概解释下各个参数的含义：
fastcgi_cache 该指令用于设置哪个缓存区将被使用，zone_name的值为fastcgi_cache_path指令创建的缓存名称
fastcgi_cache_path 作用域：http
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fastcgi_cache_path path[levels=levels] [use_temp_path=on|off] keys_zone=name:size [inactive=time][max_size=size] [loader_files=number] [loader_sleep=time] [loader_threshold=time][purger=on|off] [purger_files=number] [purger_sleep=time] [purger_threshold=time]; |
该指令用于设置缓存文件的存放路径，示例如下：fastcgi_cache_path /data/nginx/cache levels=1:2 keys_zone=cache_one:100M inactive=1d max_size=10g;
a、levels:指定了该缓存空间有两层hash目录，设置缓存目录层数，levels=1:2，表示创建两层目录缓存，最多创建三层。第一层目录名取fastcgi_cache_key md5的最后一个字符，第二层目录名取倒数2-3字符，如：fastcgi_cache_key md5为b7f54b2df7773722d382f4809d65029c，则：
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levels=1:2为/data/nginx/cache/c/29/b7f54b2df7773722d382f4809d65029clevels=1:2:3为/data/nginx/cache/c/29/650/b7f54b2df7773722d382f4809d65029c |
b、keys_zone为这个缓存区起名为zone_name,500m指代缓存空间为500MB;
c、inactive=1d 代表如果缓存文件一天内没有被访问，则删除;
d、max_size=30g代表硬盘缓存最大为30G;
设置缓存多个磁盘
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fastcgi_cache_path /path/to/hdd1 levels=1:2 keys_zone=my_cache_hdd1:10m max_size=10g inactive=60m use_temp_path=off;fastcgi_cache_path /path/to/hdd2 levels=1:2 keys_zone=my_cache_hdd2:10m max_size=10g inactive=60m use_temp_path=off;split_clients $request_uri $my_cache { 50% "my_cache_hdd1"; 50% "my_cache_hdd2";}server { ... location / { fastcgi_cache $my_cache; }} |
将缓存文件放入内存中
编辑/etc/fstab 或者 放入 /dev/shm
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tmpfs /etc/nginx/cache tmpfs defaults,size=100M 0 0mount -adf -ah | grep tmpfs |
需要注意的是fastcgi_cache缓存是先写在fastcgi_temp_path再移到fastcgi_cache_path，所以这两个目录最好在同一个分区，从0.8.9之后可以在不同的分区，不过还是建议放同一分区
fastcgi_cache_methods 该指令用于设置缓存哪些HTTP方法，默认缓存HTTP GET/HEAD方法。
fastcgi_cache_min_uses URL经过多少次请求将被缓存
fastcgi_cache_valid reply_code [reply_code ... ] time
该指令用于对不同返回状态码的URL设置不同的缓存时间，例如：
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fastcgi_cache_valid 200 302 10m;fastcgi_cache_valid 404 1m; |
设置202 302状态URL缓存10分钟，404状态的URL缓存1分钟。
注意：如果不指定状态码，直接指定缓存时间，则只有200,301,302状态码会进行缓存。
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fastcgi_cache_valid 5m; |
any 可以指定缓存任何响应码
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fastcgi_cache_valid 200 302 10m;fastcgi_cache_valid 301 1h;fastcgi_cache_valid any 1m; |
缓存的参数也可以在响应头直接设置。这些的优先级高于缓存时间设定使用该指令
- The “X-Accel-Expires” header field sets caching time of a response in seconds. The zero value disables caching for a response. If the value starts with the
@prefix, it sets an absolute time in seconds since Epoch, up to which the response may be cached. - If the header does not include the “X-Accel-Expires” field, parameters of caching may be set in the header fields “Expires” or “Cache-Control”.
- If the header includes the “Set-Cookie” field, such a response will not be cached.
- If the header includes the “Vary” field with the special value “
*”, such a response will not be cached (1.7.7). If the header includes the “Vary” field with another value, such a response will be cached taking into account the corresponding request header fields (1.7.7).
fastcgi_cache_key
该指令用来设置Web缓存的Key值，Nginx根据Key值MD5缓存。一般根据host(域名),host(域名),request_uri(请求的路径)等变量组合成fastcgi_cache_key。
例如：fastcgi_cache_key "schemeschemerequest_methodhosthostrequest_uri";
定义fastcgi_cache的key，示例中就以请求的URI作为缓存的key，Nginx会取这个key的md5作为缓存文件，如果设置了缓存哈希目录，Nginx会从后往前取相应的位数做为目录。
注意一定要加上$request_method作为cache key，否则如果HEAD类型的先请求会导致后面的GET请求返回为空
fastcgi_temp_path path [level1 [level2 [level3]]]; 默认为 fastcgi_temp;
该指令用来设置fastcgi_cache临时文件目录
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fastcgi_temp_path /spool/nginx/fastcgi_temp 1 2; |
a temporary file might look like this:
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/spool/nginx/fastcgi_temp/7/45/00000123457 |
fastcgi_cache_use_stale : fastcgi_cache_use_stale error | timeout | invalid_header | updating | http_500 | http_503 | http_403 | http_404 | off ...;
定义哪些情况下用过期缓存
x-cache头，用于调试
$upstream_response_time为过期时间
$upstream_cache_status 变量表示此请求响应来自cache的状态，几种状态分别为：
- MISS – The response was not found in the cache and so was fetched from an origin server. The response might then have been cached.
- BYPASS – The response was fetched from the origin server instead of served from the cache because the request matched a proxy_cache_bypass directive (see Can I Punch a Hole Through My Cache? below.) The response might then have been cached.
- EXPIRED – The entry in the cache has expired. The response contains fresh content from the origin server.
- STALE – The content is stale because the origin server is not responding correctly, and proxy_cache_use_stale was configured.
- UPDATING – The content is stale because the entry is currently being updated in response to a previous request, and proxy_cache_use_stale updating is configured.
- REVALIDATED – The proxy_cache_revalidate directive was enabled and NGINX verified that the current cached content was still valid (If-Modified-Since or If-None-Match).
- HIT – The response contains valid, fresh content direct from the cache.
有一些情况会影响到cache的命中 这里需要特别注意
- Nginx fastcgi_cache在缓存后端fastcgi响应时，当响应里包含“set-cookie”时，不缓存;
- 当响应头包含Expires时，如果过期时间大于当前服务器时间，则nginx_cache会缓存该响应，否则，则不缓存;
- 当响应头包含Cache-Control时，如果Cache-Control参数值为no-cache、no-store、private中任意一个时，则不缓存，如果Cache-Control参数值为max-age时，会被缓存，且nginx设置的cache的过期时间，就是系统当前时间 + mag-age的值。
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header("Expires: ".gmdate("D, d M Y H:i:s", time()+10000).' GMT');header("Expires: ".gmdate("D, d M Y H:i:s", time()-99999).' GMT');header("X-Accel-Expires:5"); // 5sheader("Cache-Control: no-cache"); //no cacheheader("Cache-Control: no-store"); //no cacheheader("Cache-Control: private"); //no cacheheader("Cache-Control: max-age=10"); //cache 10ssetcookie('hello',"testaaaa"); //no cache |
注意session使用的时候有坑，可以用下面来设置
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session_cache_limiter("none");session_start();echo date("Y-m-d H:i:s",time()); |
可以看一下PHP源代码中的头信息 Expires等
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//ext/session/session.c line:1190 左右// ...CACHE_LIMITER_FUNC(private) /* {{{ */{ ADD_HEADER("Expires: Thu, 19 Nov 1981 08:52:00 GMT"); CACHE_LIMITER(private_no_expire)(TSRMLS_C);}/* }}} *///再到这里3 或者上面几个 ##默认是nocacheCACHE_LIMITER_FUNC(nocache) /* {{{ */{ ADD_HEADER("Expires: Thu, 19 Nov 1981 08:52:00 GMT"); /* For HTTP/1.1 conforming clients and the rest (MSIE 5) */ ADD_HEADER("Cache-Control: no-store, no-cache, must-revalidate, post-check=0, pre-check=0"); /* For HTTP/1.0 conforming clients */ ADD_HEADER("Pragma: no-cache");}/* }}} *///这里2static php_session_cache_limiter_t php_session_cache_limiters[] = { CACHE_LIMITER_ENTRY(public) CACHE_LIMITER_ENTRY(private) CACHE_LIMITER_ENTRY(private_no_expire) CACHE_LIMITER_ENTRY(nocache) {0}}; static int php_session_cache_limiter(TSRMLS_D) /* {{{ */{ php_session_cache_limiter_t *lim; if (PS(cache_limiter)[0] == '\0') return 0; if (SG(headers_sent)) { const char *output_start_filename = php_output_get_start_filename(TSRMLS_C); int output_start_lineno = php_output_get_start_lineno(TSRMLS_C); if (output_start_filename) { php_error_docref(NULL TSRMLS_CC, E_WARNING, "Cannot send session cache limiter - headers already sent (output started at %s:%d)", output_start_filename, output_start_lineno); } else { php_error_docref(NULL TSRMLS_CC, E_WARNING, "Cannot send session cache limiter - headers already sent"); } return -2; } for (lim = php_session_cache_limiters; lim->name; lim++) { if (!strcasecmp(lim->name, PS(cache_limiter))) { lim->func(TSRMLS_C); //这里1 return 0; } } return -1;} |
三、清除缓存
NGINX只在商业版中支持proxy_cache_purge指令清除缓存，开源的ngx_cache_purge模块只支持单一key的缓存清除。为了实现按目录清除缓存只能自己开发。
NGINX作为Cache服务器时将资源内容以文件形式进行缓存，缓存元信息存储于共享内存中，组织成一棵红黑树。红黑树中的每个节点代表一个Cache元信息。NGINX将Cache Key的HASH值作为红黑树节点的KEY。内容缓存文件以该HASH值作为文件名存储在磁盘上。
NGINX的处理流程简化描述是这样的：当请求到达时，根据Cache Key的HASH值在红黑树中进行查找。如果找到，并查看相关信息，如果Cache可用，返回相应的Cache文件。否则，则回源抓取。
因为元信息是以Cache Key的HASH值作为Key存储的，因而红黑树中并不能保留Cache Key中有层级关系. 如”/uri/foo”和”/uri/bar”在元信息红黑树中完全没有关系。要实现按照目录清除缓存，需要将Cache Key中层次关系存储起来。
可以这样做，在共享内存中建立一棵目录树来存储层级关系。将Cache Key类比于文件系统中的路径, 每级路径存储为树中的一个节点。当需要清除某一目录下的所有缓存时，将该节点子树的中的所有缓存清除即可。
安装Purge模块
Purge模块被用来清除缓存
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wget http://labs.frickle.com/files/ngx_cache_purge-1.2.tar.gztar -zxvf ngx_cache_purge-1.2.tar.gz |
编译
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./configure \…… \--with-http_geoip_module \--add-module=/usr/local/ngx_cache_purge-1.2 |
四、需要注意的一些问题
设置了之后重启nginx就可以生效了，这个时候再访问php的页面的话，就会被缓存了，可以查看/var/logs/nginx/fastcgi_cache_dir这个目录下面是有缓存文件的。最后再说明一点，如果更改了缓存目录的路径，一定要把缓存的名称也改掉，后端调用的名称也同步改掉，如果只改掉了缓存目录，不改缓存名称的话，缓存的时候还是会缓存到之前的路径下面去，但是调用的时候调用的是新的路径，这个时候就会出现找不到的情况
参考文章
http://www.nginxtips.com/configure-nginx-fastcgi-cache/
http://www.haidx.com/fastcgi-cache-details.html
http://www.just4coding.com/blog/2014/11/01/nginx-purge-directory/
http://weizhifeng.net/nginx-proxy-cache.html
https://www.nginx.com/blog/nginx-caching-guide/#gs.6PdbraI
http://nginx.org/en/docs/http/ngx_http_fastcgi_module.html#fastcgi_cache
https://www.cnxct.com/several-reminder-in-nginx-fastcgi_cache-and-php-session_cache_limiter/
https://rtcamp.com/wordpress-nginx/tutorials/single-site/fastcgi-cache-with-purging/
http://nginx.org/en/docs/http/ngx_http_fastcgi_module.html#fastcgi_cache
本文来自博客园，作者：sunsky303，转载请注明原文链接：https://www.cnblogs.com/sunsky303/p/11045194.html
