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Nginx

Nginx - 代理、缓存

發(fā)布時間：2025/3/17 Nginx 32 豆豆
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Nginx

標(biāo)簽 ： nginx

代理

代理服務(wù)可簡單的分為正向代理和反向代理:

  • 正向代理: 用于代理內(nèi)部網(wǎng)絡(luò)對Internet的連接請求(如VPN/NAT),客戶端指定代理服務(wù)器,并將本來要直接發(fā)送給目標(biāo)Web服務(wù)器的HTTP請求先發(fā)送到代理服務(wù)器上, 然后由代理服務(wù)器去訪問Web服務(wù)器, 并將Web服務(wù)器的Response回傳給客戶端:

  • 反向代理: 與正向代理相反,如果局域網(wǎng)向Internet提供資源,并讓Internet上的其他用戶可以訪問局域網(wǎng)內(nèi)資源, 也可以設(shè)置一個代理服務(wù)器, 它提供的服務(wù)就是反向代理. 反向代理服務(wù)器接受來自Internet的連接,然后將請求轉(zhuǎn)發(fā)給內(nèi)部網(wǎng)絡(luò)上的服務(wù)器,并將Response回傳給Internet上請求連接的客戶端:

  • 總結(jié)來說:

    • 正向代理和客戶端同屬一個陣營,對于目標(biāo)服務(wù)器來說,可將他們看成一個客戶端;
    • 反向代理和目標(biāo)服務(wù)器同屬一個陣營,對于客戶端來說,他們”偽裝”成了一個目標(biāo)服務(wù)器.

正向代理

由于使用Nginx做正向代理服務(wù)的相對較少, 因此Nginx提供的代理服務(wù)本身也比較簡單, 提供的指令也不多, 直接由ngx_http_core_module模塊支持.

指令

  • resolver
Syntax: resolver address ... [valid=time] [ipv6=on|off]; Default: — Context: http, server, location - address: DNS服務(wù)器IP地址, 如果不指定端口號, 默認(rèn)使用53; 從1.1.7版本開始, 該指令支持多個IP地址. - time: 設(shè)置數(shù)據(jù)包在網(wǎng)絡(luò)中的有效時間.
  • resolver_timeout
Syntax: resolver_timeout time; Default: resolver_timeout 30s; Context: http, server, location 設(shè)置DNS服務(wù)器域名解析超時時間.
  • proxy_pass
Syntax: proxy_pass URL; Default: — Context: location, if in location, limit_except 設(shè)置被代理服務(wù)器的協(xié)議和地址,在正向代理中,該指令的配置相對固定: proxy_pass http://$http_host$request_uri;

注: proxy_pass不僅用于正向代理,更主要是應(yīng)用于反向代理服務(wù),后面還有關(guān)于它的詳細(xì)敘述.

示例

server {listen 8001;resolver 192.168.111.9 192.168.111.8 192.168.100.8 192.168.100.9;location / {proxy_pass http://$http_host$request_uri;}error_page 500 502 503 504 /50x.html;location = /50x.html {root html;}}

注意:
1. 在配置正向代理的server塊中,不要使用server_name指令,即不能設(shè)置虛擬主機(jī)名或IP.
2. Nginx正向代理不支持代理HTTPS站點.

反向代理

反向代理是Nginx最常用且最重要的功能之一,由標(biāo)準(zhǔn)HTTP模塊ngx_http_proxy_model支持.同正向代理類似,反向代理一般也單獨配置一個server塊.

指令

  • proxy_pass
Syntax: proxy_pass URL; Default: — Context: location, if in location, limit_except

同正向代理, 該指令用來配置被代理服務(wù)器地址,可以是主機(jī)名稱/IP地址+端口號等形式:

proxy_pass http://localhost:8000/uri/;
  • upstream
Syntax: upstream name { ... } Default: — Context: http

如果被代理的是一組服務(wù)器的話, 可以使用upstream指令配置一組后端服務(wù)器.Defines a group of servers. Servers can listen on different por ts. In addition, servers listening on TCP and UNIX-domain sockets can be mixed.

http {## ...upstream proxy_servs {server 10.45.156.170:80;server 10.45.156.171:80;server 10.45.156.172:80;}server {location ~* \.(do|jsp|jspx)?$ {proxy_pass http://proxy_servs;}## ...} }

注意: 對于proxy_pass/server指令后的URL中是否包含URI, Nginx有不同的處理方式:
1. 如果URL中不包含URI, 則Nginx不會改變原地址的URI;
2. 如果URL中包含了URI, 則Nginx會使用新的URI 代替 原來的URI.

  • 其他反向代理指令
指令描述
proxy_pass_request_headers on | off;Indicates whether the header fields of the original request are passed to the proxied server.
proxy_pass_request_body on | off;Indicates whether the original request body is passed to the proxied server.
proxy_set_header field value;Allows redefining or appending fields to the request header passed to the proxied server.
proxy_set_body value;Allows redefining the request body passed to the proxied server.
proxy_hide_header field;The proxy_hide_header directive sets additional fields that will not be passed.
proxy_pass_header field;Permits passing “Date”, “Server”, “X-Pad” and “X-Accel-…” header fields from a proxied server to a client.
proxy_bind address [transparent] | off;Makes outgoing connections to a proxied server originate from the specified local IP address.
proxy_connect_timeout time;Defines a timeout for establishing a connection with a proxied server.
proxy_read_timeout time;Defines a timeout for reading a response from the proxied server.
proxy_send_timeout time;Sets a timeout for transmitting a request to the proxied server.
proxy_http_version 1.0 | 1.1;Sets the HTTP protocol version for proxying. By default, version 1.0 is used.
proxy_method method;Specifies the HTTP method to use in requests forwarded to the proxied server instead of the method from the client request.
proxy_ignore_client_abort on | off;Determines whether the connection with a proxied server should be closed when a client closes the connection without waiting for a response.
proxy_ignore_headers field ...;Disables processing of certain response header fields from the proxied server.
proxy_redirect default | off | redirect replacement;Sets the text that should be changed in the “Location” and “Refresh” header fields of a proxied server response.
proxy_intercept_errors on | off;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.
proxy_headers_hash_max_size size;Sets the maximum size of hash tables used by the proxy_hide_header and proxy_set_header directives.
proxy_headers_hash_bucket_size size;Sets the bucket size for hash tables used by the proxy_hide_header and proxy_set_header directives.
proxy_next_upstream [flag];Specifies in which cases a request should be passed to the next server, detail
proxy_ssl_session_reuse on | off;Determines whether SSL sessions can be reused when working with the proxied server.

Proxy-Buffer

Proxy Buffer啟用后,Nginx會將被代理的服務(wù)器的響應(yīng)數(shù)據(jù)異步地傳遞給客戶端:

Nginx首先盡可能地從后端服務(wù)器那里接收響應(yīng)數(shù)據(jù)放在*Buffer*中,如果在接收過程中發(fā)現(xiàn)*Buffer*已經(jīng)裝滿,Nginx會將部分接收到的數(shù)據(jù)臨時存放到磁盤的臨時文件中.當(dāng)一次響應(yīng)數(shù)據(jù)被萬千接收或*Buffer*已經(jīng)裝滿時,Nginx開始向客戶端傳輸數(shù)據(jù).此時Nginx處于`BUSY`狀態(tài).

而當(dāng)Proxy Buffer關(guān)閉時, Nginx只要接收到響應(yīng)數(shù)據(jù)就會同步地傳遞給客戶端,不會讀取完整響應(yīng)數(shù)據(jù).

指令描述
proxy_buffering on | off;Enables or disables buffering of responses from the proxied server.
proxy_buffers number size;Sets the number and size of the buffers used for reading a response from the proxied server, for a single connection.
proxy_buffer_size size;Sets the size of the buffer used for reading the first part of the response received from the proxied server.
proxy_busy_buffers_size size;When buffering of responses from the proxied server is enabled, limits the total size of buffers that can be busy sending a response to the client while the response is not yet fully read.
proxy_temp_path path [level1 [level2 [level3]]];Defines a directory for storing temporary files with data received from proxied servers.
proxy_temp_file_write_size size;Limits the size of data written to a temporary file at a time, when buffering of responses from the proxied server to temporary files is enabled.
proxy_max_temp_file_size size;This directive sets the maximum size of the temporary file.

注意: Proxy Buffer配置是針對每一個請求起作用,而不是全局概念,即每個請求都會按照這些指令來配置各自的Buffer, Nginx不會生成一個公共的Proxy Buffer供代理請求使用.

負(fù)載均衡

Nginx反向代理的一個重要用途就是負(fù)載均衡:

負(fù)載均衡的原理是利用一定的分配策略將網(wǎng)絡(luò)負(fù)載平衡地分?jǐn)偟骄W(wǎng)絡(luò)集群的各個節(jié)點, 使得單個重負(fù)載任務(wù)能夠分擔(dān)到多個單元上并行處理,或使得大量的并發(fā)訪問數(shù)據(jù)流量分?jǐn)偟蕉鄠€節(jié)點上分別處理,從而減少用戶的等待響應(yīng)時間.

在實際應(yīng)用中, 負(fù)載均衡會根據(jù)網(wǎng)絡(luò)的不同層次(一般按照ISO/OSI七層參考模型)進(jìn)行劃分. 現(xiàn)代負(fù)載均衡技術(shù)主要實現(xiàn)和作用于第四層/第七層,完全獨立于網(wǎng)絡(luò)基礎(chǔ)硬件設(shè)備; Nginx一般被認(rèn)為是第七層負(fù)載均衡.
負(fù)載均衡算法多種多樣: 靜態(tài)負(fù)載均衡算法/動態(tài)負(fù)載均衡算法.靜態(tài)負(fù)載均衡算法比較簡單,主要有一般輪詢算法/基于比率的加權(quán)輪詢算法以及基于優(yōu)先級的加權(quán)輪詢算法等.動態(tài)負(fù)載均衡算法在較復(fù)雜的網(wǎng)絡(luò)環(huán)境中適應(yīng)性更強(qiáng),表現(xiàn)更好,主要有基于任務(wù)量的最少連接優(yōu)先算法/基于性能的最快響應(yīng)優(yōu)先算法/預(yù)測算法以及動態(tài)性能分配算法等; Nginx實現(xiàn)采用基于優(yōu)先級的加權(quán)輪詢算法.

Nginx負(fù)載均衡

前在介紹upstream時使用了對所有請求的一般輪詢規(guī)則的負(fù)載均衡, 下面介紹基于優(yōu)先級的加權(quán)輪詢規(guī)則的負(fù)載均衡:

http {## ...upstream proxy_servs {server 10.45.156.170:80 weight=5;server 10.45.156.171:80 weight=2;server 10.45.156.172:80; #默認(rèn)weight=1}server {location ~* \.(do|jsp|jspx)?$ {proxy_pass http://proxy_servs;}## ...} }

upstream的服務(wù)器組中每個server被賦予了不同的優(yōu)先級,weight就是輪詢策略的”權(quán)值”, 其中以10.45.156.170:80優(yōu)先級最高.

緩存

響應(yīng)速度是衡量Web應(yīng)用服務(wù)性能優(yōu)劣的重要指標(biāo)之一,在動態(tài)網(wǎng)站中,除了優(yōu)化發(fā)布的內(nèi)容本身之外,另一個重要的方法就是把不需要實時更新的動態(tài)頁面輸出結(jié)果轉(zhuǎn)化成靜態(tài)頁面緩存,進(jìn)而按照靜態(tài)網(wǎng)頁來訪問,提升響應(yīng)速度.

緩存驅(qū)動技術(shù)

在Nginx中, 緩存驅(qū)動技術(shù)有兩種:

404驅(qū)動

  • 原理:

    Nginx處理客戶端請求時,一旦發(fā)現(xiàn)請求資源不存在,則會產(chǎn)生404錯誤,Nginx通過捕獲該錯誤,進(jìn)一步轉(zhuǎn)向后端服務(wù)器請求數(shù)據(jù),最后將后端服務(wù)器響應(yīng)數(shù)據(jù)傳回給客戶端,同時在本地進(jìn)行緩存.

  • 配置:

location / {root html;error_page 404 =200 @send_to_backend; }location @send_to_backend {internal;proxy_pass http://proxy_servs;proxy_set_header Accept-Encoding "";proxy_store on;proxy_store_access user:rw group:rw all:r;proxy_temp_path /var/www/tmp; }

proxy_store指令是由Nginx-Proxy Store模塊提供的簡單緩存機(jī)制,詳見下文介紹.

資源不存在驅(qū)動

  • 原理:

    與404驅(qū)動大同小異, 該方法時通過location塊中的if條件判斷直接判斷請求資源是否存在, 不存在則直接驅(qū)動Nginx與后端服務(wù)器通信更新Web緩存.

  • 配置:

location / {root html;proxy_set_header Accept-Encoding "";proxy_store on;proxy_store_access user:rw group:rw all:r;proxy_temp_path /var/www/tmp;if ( !-f $request_filename ){proxy_pass http://proxy_servs;} }

!-f判斷請求資源是否存,如不存在就proxy_pass給后端服務(wù)器生成數(shù)據(jù)傳給客戶端,同時Proxy Store緩存.

Nginx緩存

Nginx自身實現(xiàn)了兩種緩存機(jī)制, Proxy Cache/Proxy Store:

Proxy Cache

Proxy Cache是Nginx自身實現(xiàn)的一個功能完整,性能不錯的緩存機(jī)制.Nginx服務(wù)啟動后, 會生成專門的進(jìn)程對磁盤上的緩存文件進(jìn)行掃描, 在內(nèi)存中建立緩存索引, 提高訪問效率, 并且還會生成專門的管理進(jìn)程對磁盤上的緩存文件進(jìn)行過期判定/更新等方面的管理. Proxy Cache緩存支持任意連接響應(yīng)數(shù)據(jù)的緩存, 不僅限于200狀態(tài)的數(shù)據(jù).

與前面介紹過的Proxy Buffer不同:Proxy Buffer實現(xiàn)了后端服務(wù)器響應(yīng)數(shù)據(jù)的異步傳輸, 而Proxy Cahce則實現(xiàn)了Nginx對客戶端數(shù)據(jù)請求的快速響應(yīng). Nginx在接收到后端服務(wù)器響應(yīng)數(shù)據(jù)后, 一方面通過Proxy Buffer機(jī)制將數(shù)據(jù)傳遞給客戶端, 另一方面根據(jù)Proxy Cahce的配置將這些數(shù)據(jù)緩存到本地, 當(dāng)客戶端下次訪問相同數(shù)據(jù)時, Nginx直接從本地檢索數(shù)據(jù)返回給客戶端, 從而減少與后端服務(wù)器的交互時間.

指令描述
proxy_cache zone | off;Defines a shared memory zone used for caching.
proxy_cache_bypass string ...;Defines conditions under which the response will not be taken from a cache.
proxy_cache_key string;Defines a key for caching.
proxy_cache_lock on | off;When enabled, only one request at a time will be allowed to populate a new cache element identified according to the proxy_cache_key directive by passing a request to a proxied server.
proxy_cache_lock_timeout time;Sets a timeout for proxy_cache_lock.
proxy_cache_min_uses number;Sets the number of requests after which the response will be cached.
proxy_cache_use_stale [stale]Determines in which cases a stale cached response can be used when an error occurs during communication with the proxied server. The directive’s parameters match the parameters of the proxy_next_upstream directive.
proxy_cache_valid [code ...] time;Sets caching time for different response codes.
proxy_cache_path path keys_zone=name:size;Sets the path and other parameters of a cache
proxy_no_cache string ...;Defines conditions under which the response will not be saved to a cache.
http {## ...upstream proxy_servs {server 10.45.156.170:80;server 10.45.156.171:80;server 10.45.156.172:80;}proxy_cache_path /var/www/proxycache levels=1:2 max_size=2m inactive=5m loader_sleep=1m keys_zone=MYPROXYCACHE:10m;proxy_temp_path /var/www/tmp;server {## ...location / {proxy_pass http://proxy_servs;proxy_cache MYPROXYCACHE;proxy_cache_valid 200 302 1h;proxy_cache_valid 301 1d;proxy_cache_valid any 1m;}location @send_to_backend {proxy_pass http://proxy_servs;}} }

注: Proxy Cache依賴于Proxy Buffer.且Proxy Cache沒有實現(xiàn)自動清理磁盤上緩存數(shù)據(jù)的能力, 因此在長時間使用過程中會對服務(wù)器存儲造成一定的壓力.

Proxy Store

Nginx還支持另一種將后端服務(wù)器數(shù)據(jù)緩存到本地的方法Proxy Store, 與Proxy Cache的區(qū)別是, 它對來自后端服務(wù)器的響應(yīng)數(shù)據(jù), 尤其是靜態(tài)數(shù)據(jù)只進(jìn)行簡單的緩存, 且只能緩存200狀態(tài)碼下的響應(yīng)數(shù)據(jù), 不支持緩存過期更新, 內(nèi)存索引建立等功能, 但支持設(shè)置用戶/用戶組對緩存的訪問權(quán)限.

指令描述
proxy_store on | off | string;Enables saving of files to a disk.
proxy_store_access users:permissions ...;Sets access permissions for newly created files and directories.

Memcached緩存

Memcached是一套高性能的基于分布式環(huán)境的緩存系統(tǒng),用于動態(tài)Web應(yīng)用可減輕后臺數(shù)據(jù)服務(wù)器的負(fù)載, 提高客戶端響應(yīng)速度.Nginx的標(biāo)準(zhǔn)模塊ngx_http_memcached_module提供了對Memcached的支持.

指令描述
memcached_pass address;Sets the memcached server address.
memcached_connect_timeout time;Defines a timeout for establishing a connection with a memcached server.
memcached_read_timeout time;Defines a timeout for reading a response from the memcached server.
memcached_send_timeout time;Sets a timeout for transmitting a request to the memcached server.
memcached_buffer_size size;Sets the size of the buffer used for reading the response received from the memcached server.
memcached_next_upstream status ...Specifies in which cases a request should be passed to the next server.

在配置Nginx使用Memcached時,還需要對Nginx配置的全局變量$memcached_key進(jìn)行設(shè)置.

示例

Nginx首先請求Memcached, 如果緩存沒有命中(key為"$uri?$args"), Nginx則proxy_pass給后端服務(wù)器響應(yīng)該請求, 但此時也需要后端服務(wù)器配合, 在將數(shù)據(jù)響應(yīng)給客戶端之后, 需要將響應(yīng)內(nèi)容手動寫入Memcached, 以供下次直接從Memcached檢索數(shù)據(jù).

  • nginx.conf
location / {set $memcached_key "$uri?$args";memcached_pass 127.0.0.1:11211;error_page 404 =200 @send_to_backend;index index.html index.htm; }location @send_to_backend {proxy_pass http://proxy_servs; }
  • Java: MemcachedFilter
/*** @author jifang.* @since 2016/5/21 15:50.*/ public class MemcachedFilter implements Filter {private MemcachedClient memcached;private static final int _1MIN = 60;@Overridepublic void init(FilterConfig filterConfig) throws ServletException {try {MemcachedClientBuilder builder = new XMemcachedClientBuilder(AddrUtil.getAddresses("127.0.0.1:11211"));memcached = builder.build();} catch (IOException e) {throw new RuntimeException(e);}}@Overridepublic void doFilter(ServletRequest req, ServletResponse response, FilterChain chain) throws IOException, ServletException {// 對PrintWriter包裝MemcachedWriter mWriter = new MemcachedWriter(response.getWriter());chain.doFilter(req, new MemcachedResponse((HttpServletResponse) response, mWriter));HttpServletRequest request = (HttpServletRequest) req;String key = request.getRequestURI();Enumeration<String> names = request.getParameterNames();if (names.hasMoreElements()) {String name = names.nextElement();StringBuilder sb = new StringBuilder(key).append("?").append(name).append("=").append(request.getParameter(name));while (names.hasMoreElements()) {name = names.nextElement();sb.append("&").append(name).append("=").append(request.getParameter(name));}key = sb.toString();}try {String rspContent = mWriter.getRspContent();memcached.set(key, _1MIN, rspContent);} catch (TimeoutException | InterruptedException | MemcachedException e) {throw new RuntimeException(e);}}@Overridepublic void destroy() {}private static class MemcachedWriter extends PrintWriter {private StringBuilder sb = new StringBuilder();private PrintWriter writer;public MemcachedWriter(PrintWriter out) {super(out);this.writer = out;}@Overridepublic void print(String s) {sb.append(s);this.writer.print(s);}public String getRspContent() {return sb.toString();}}private static class MemcachedResponse extends HttpServletResponseWrapper {private PrintWriter writer;public MemcachedResponse(HttpServletResponse response, PrintWriter writer) {super(response);this.writer = writer;}@Overridepublic PrintWriter getWriter() throws IOException {return this.writer;}} }

分布式Memcached

為了充分發(fā)揮Memcached分布式優(yōu)勢,提升服務(wù)器響應(yīng)速度,我們使用Nginx的一致性Hash模塊, 將request分布到不同的Memcached Server中, 同時, 對于訪問不命中的情況, 也需要后端服務(wù)器的支持, 后端服務(wù)器在對客戶端做出響應(yīng)的同時, 需要將響應(yīng)數(shù)據(jù)按照一致性Hash規(guī)則, 將響應(yīng)數(shù)據(jù)寫入Memcached.

  • 安裝Nginx一致性Hash模塊

    • git clone https://github.com/replay/ngx_http_consistent_hash.git
    • ./configure --add-module=/root/src/ngx_http_consistent_hash/
    • make && make install

    Nginx官方還提供了其他一致性Hash算法的實現(xiàn), 詳細(xì)可參考https://www.nginx.com/resources/wiki/modules/

  • 配置Memcached一致性Hash規(guī)則

  • upstream memcached_servs {consistent_hash "$uri?$args";server 127.0.0.1:11211;server 127.0.0.1:11212;server 127.0.0.1:11213;}server {location / {set $memcached_key "$uri?$args";memcached_pass memcached_servs;error_page 404 =200 @send_to_backend;index index.html index.htm;}}


    • Java: MemcachedFilter

    注意: Java端的一致性Hash算法的選用需要和Nginx一致, 否則會出現(xiàn)Nginx讀取的Memcached與Java寫入的Memcached不在同一臺的情況. public class MemcachedFilter implements Filter {private MemcachedClient memcached;@Overridepublic void init(FilterConfig filterConfig) throws ServletException {try {MemcachedClientBuilder builder = new XMemcachedClientBuilder(AddrUtil.getAddresses("127.0.0.1:11211 127.0.0.1:11212 127.0.0.1:11213"));builder.setSessionLocator(new ElectionMemcachedSessionLocator());memcached = builder.build();} catch (IOException e) {throw new RuntimeException(e);}}// ... }

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