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<h3 id="负载均衡是什么">负载均衡是什么？<a role="anchor" aria-hidden="true" tabindex="-1" data-no-popover="true" href="#负载均衡是什么" class="internal"><svg width="18" height="18" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><path d="M10 13a5 5 0 0 0 7.54.54l3-3a5 5 0 0 0-7.07-7.07l-1.72 1.71"></path><path d="M14 11a5 5 0 0 0-7.54-.54l-3 3a5 5 0 0 0 7.07 7.07l1.71-1.71"></path></svg></a></h3>
<blockquote>
<p>负载均衡是现代高可用、高性能网站架构的核心组件。</p>
</blockquote>
<p>负载均衡（Server Load Balancer，简称 SLB）是一种网络负载均衡服务，它在多个服务器（通常称为后端服务器）之间分配网络或应用程序流量。这样做的目的是优化资源使用，最大化吞吐量，最小化响应时间，并确保高可用性。</p>
<pre><code class="mermaid">graph TD;
subgraph Client
A[客户端] --> B[负载均衡器]
end
subgraph LoadBalancer
B --> C[服务器1]
B --> D[服务器2]
B --> E[服务器3]
end
</code></pre>
<h3 id="负载均衡的重要性">负载均衡的重要性<a role="anchor" aria-hidden="true" tabindex="-1" data-no-popover="true" href="#负载均衡的重要性" class="internal"><svg width="18" height="18" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><path d="M10 13a5 5 0 0 0 7.54.54l3-3a5 5 0 0 0-7.07-7.07l-1.72 1.71"></path><path d="M14 11a5 5 0 0 0-7.54-.54l-3 3a5 5 0 0 0 7.07 7.07l1.71-1.71"></path></svg></a></h3>
<ul>
<li><strong>可靠性</strong>：如果一个服务器失败，负载均衡器可以将流量重定向到健康的服务器，确保服务的持续性。</li>
<li><strong>可扩展性</strong>：随着需求的增加，可以轻松地添加更多的服务器来处理增加的流量。</li>
<li><strong>性能</strong>：通过分配请求，确保没有单个服务器承受过多的负载。</li>
<li><strong>灵活性</strong>：负载均衡器可以动态地添加或删除服务器，以应对不同的负载需求。</li>
</ul>
<h3 id="负载均衡的方法">负载均衡的方法<a role="anchor" aria-hidden="true" tabindex="-1" data-no-popover="true" href="#负载均衡的方法" class="internal"><svg width="18" height="18" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><path d="M10 13a5 5 0 0 0 7.54.54l3-3a5 5 0 0 0-7.07-7.07l-1.72 1.71"></path><path d="M14 11a5 5 0 0 0-7.54-.54l-3 3a5 5 0 0 0 7.07 7.07l1.71-1.71"></path></svg></a></h3>
<ul>
<li>
<p><strong>轮询（Round Robin）</strong>：每个请求按顺序轮流分配到不同的服务器。这种方法简单且易于实现，<strong>适用于服务器性能大致相同的场景。</strong></p>
<pre><code class="mermaid">sequenceDiagram
participant Client
participant LoadBalancer
participant Server1
participant Server2
Client->>LoadBalancer: 发送请求
LoadBalancer->>Server1: 将请求转发给Server1
Server1->>LoadBalancer: 处理请求并响应
LoadBalancer->>Client: 将Server1的响应返回给Client
Client->>LoadBalancer: 发送请求
LoadBalancer->>Server2: 将请求转发给Server2
Server2->>LoadBalancer: 处理请求并响应
LoadBalancer->>Client: 将Server2的响应返回给Client
Note right of LoadBalancer: 下一轮请求会轮询到Server1
</code></pre>
</li>
<li>
<p><strong>最少连接（Least Connections）</strong>：新的请求会被发送到连接数最少的服务器。这种方法<strong>适用于处理长时间运行的连接或会话。</strong></p>
<pre><code class="mermaid">sequenceDiagram
participant Client
participant LoadBalancer
participant Server1
participant Server2
participant Server3
Client->>LoadBalancer: 发送请求
LoadBalancer->>Server1: 将请求转发给Server1
Server1->>LoadBalancer: 处理请求并响应
LoadBalancer->>Client: 将Server1的响应返回给Client
Client->>LoadBalancer: 发送请求
LoadBalancer->>Server2: 将请求转发给Server2
Server2->>LoadBalancer: 处理请求并响应
LoadBalancer->>Client: 将Server2的响应返回给Client
Client->>LoadBalancer: 发送请求
LoadBalancer->>Server3: 将请求转发给Server3
Server3->>LoadBalancer: 处理请求并响应
LoadBalancer->>Client: 将Server3的响应返回给Client
Client->>LoadBalancer: 发送请求
LoadBalancer->>Server1: 将请求转发给Server1（因为Server1连接数最少）
Server1->>LoadBalancer: 处理请求并响应
LoadBalancer->>Client: 将Server1的响应返回给Client
Note right of LoadBalancer: 使用最小连接数策略
</code></pre>
</li>
<li>
<p><strong>哈希（Hash）</strong>：根据请求的参数（如客户端 IP 地址、URL、Cookie 等）Hash 决定将请求发送到哪个服务器，<strong>确保来自同一客户端的请求总是被发送到同一服务器</strong>。这种方法有助于实现会话持久性，适用于需要维持用户状态的应用。</p>
<pre><code class="mermaid">sequenceDiagram
participant Client
participant LoadBalancer
participant Server1
participant Server2
participant Server3
Client->>LoadBalancer: 发送请求
LoadBalancer->>Server1: 根据客户端IP哈希值选择Server1
Server1->>LoadBalancer: 处理请求并响应
LoadBalancer->>Client: 将Server1的响应返回给Client
Client->>LoadBalancer: 发送请求
LoadBalancer->>Server2: 根据客户端IP哈希值选择Server2
Server2->>LoadBalancer: 处理请求并响应
LoadBalancer->>Client: 将Server2的响应返回给Client
Client->>LoadBalancer: 发送请求
LoadBalancer->>Server3: 根据客户端IP哈希值选择Server3
Server3->>LoadBalancer: 处理请求并响应
LoadBalancer->>Client: 将Server3的响应返回给Client
Note right of LoadBalancer: 使用IP哈希策略
</code></pre>
</li>
</ul>
<h2 id="nginx-负载均衡">Nginx 负载均衡<a role="anchor" aria-hidden="true" tabindex="-1" data-no-popover="true" href="#nginx-负载均衡" class="internal"><svg width="18" height="18" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><path d="M10 13a5 5 0 0 0 7.54.54l3-3a5 5 0 0 0-7.07-7.07l-1.72 1.71"></path><path d="M14 11a5 5 0 0 0-7.54-.54l-3 3a5 5 0 0 0 7.07 7.07l1.71-1.71"></path></svg></a></h2>
<p>Nginx 是一个轻量级的 Web 服务器/反向代理服务器及电子邮件（IMAP/POP3）代理服务器，并在一个 BSD-like 协议下发行。由于其高性能、稳定性、丰富的功能集、简单的配置以及低资源消耗，Nginx 在全球范围内被广泛使用，包括知名的大型网站和服务。</p>
<p>**在 Nginx 中，负载均衡通常可以分为两大类：七层（HTTP ）负载均衡和四层（TCP/UDP）负载均衡。**每种类型都有其特定的用途和配置方法。</p>
<h3 id="七层http-负载均衡">七层（HTTP ）负载均衡<a role="anchor" aria-hidden="true" tabindex="-1" data-no-popover="true" href="#七层http-负载均衡" class="internal"><svg width="18" height="18" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><path d="M10 13a5 5 0 0 0 7.54.54l3-3a5 5 0 0 0-7.07-7.07l-1.72 1.71"></path><path d="M14 11a5 5 0 0 0-7.54-.54l-3 3a5 5 0 0 0 7.07 7.07l1.71-1.71"></path></svg></a></h3>
<p>七层负载均衡操作于应用层，直接处理消息内容。它主要处理基于 TCP 的流量，如 HTTP。通过分析消息内容（例如 URL 或 cookie），进行更精细的路由决策。Nginx 提供了以下关键特性：</p>
<ul>
<li><strong>灵活的负载均衡算法</strong>：包括轮询、最少连接和 IP 哈希等。</li>
<li><strong>健康检查</strong>：周期性地检查后端服务器的健康状态，确保流量仅被路由到健康的服务器。Nginx Plus 版本提供更高级的健康检查功能，包括被动和主动健康检查。</li>
<li><strong>SSL 终止</strong>：在负载均衡器层面处理 SSL 连接，有效减轻后端服务器的加密和解密负担。</li>
<li><strong>会话持久性</strong>：通过特定的策略（如 cookie 或 IP 哈希）保持用户会话与同一后端服务器的连接。</li>
<li><strong>动态内容处理</strong>：能够根据请求路径（URI）或请求头等条件将流量智能地路由到不同的应用或服务。</li>
<li><strong>高级缓存功能</strong>：提供高效的缓存机制，减少后端服务器的压力并加快内容的响应速度。</li>
</ul>
<h4 id="配置示例">配置示例<a role="anchor" aria-hidden="true" tabindex="-1" data-no-popover="true" href="#配置示例" class="internal"><svg width="18" height="18" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><path d="M10 13a5 5 0 0 0 7.54.54l3-3a5 5 0 0 0-7.07-7.07l-1.72 1.71"></path><path d="M14 11a5 5 0 0 0-7.54-.54l-3 3a5 5 0 0 0 7.07 7.07l1.71-1.71"></path></svg></a></h4>
<figure data-rehype-pretty-code-figure><pre tabindex="0" data-language="nginx" data-theme="github-light github-dark"><code data-language="nginx" data-theme="github-light github-dark" style="display:grid;"><span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">http</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> {</span></span>
<span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> upstream</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> myapp </span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">{</span></span>
<span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> server</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> backend1.example.com;</span></span>
<span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> server</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> backend2.example.com;</span></span>
<span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> server</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> backend3.example.com;</span></span>
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> }</span></span>
<span data-line> </span>
<span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> server</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> {</span></span>
<span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> listen </span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">80</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">;</span></span>
<span data-line> </span>
<span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> location</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> / </span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">{</span></span>
<span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> proxy_pass </span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">http://myapp;</span></span>
<span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> proxy_set_header </span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">Host $host;</span></span>
<span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> proxy_set_header </span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">X-Real-IP $remote_addr;</span></span>
<span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> proxy_set_header </span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">X-Forwarded-For $proxy_add_x_forwarded_for;</span></span>
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> }</span></span>
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> }</span></span>
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">}</span></span></code></pre></figure>
<p>在这个配置中，所有到达端口 80 的 HTTP 请求都会被转发到 <code>myapp</code> 这个上游服务器组，Nginx 将会轮询 <code>backend1</code>、<code>backend2</code>、和 <code>backend3</code> 服务器。</p>
<h3 id="四层tcpudp负载均衡">四层（TCP/UDP）负载均衡<a role="anchor" aria-hidden="true" tabindex="-1" data-no-popover="true" href="#四层tcpudp负载均衡" class="internal"><svg width="18" height="18" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><path d="M10 13a5 5 0 0 0 7.54.54l3-3a5 5 0 0 0-7.07-7.07l-1.72 1.71"></path><path d="M14 11a5 5 0 0 0-7.54-.54l-3 3a5 5 0 0 0 7.07 7.07l1.71-1.71"></path></svg></a></h3>
<p>Nginx 在作为四层负载均衡器时，处理非 HTTP 流量，如数据库连接、邮件服务或其他自定义 TCP/UDP 协议。这一功能自 Nginx 1.9.0 版本起被引入，后续版本中增加了对 UDP 的支持。</p>
<p>四层负载均衡器在 OSI 网络模型的传输层上操作，直接处理网络数据包。不同于应用层的七层负载均衡，四层负载均衡通过转发 TCP/UDP 流量，提供高效率和高可用性的服务。</p>
<ul>
<li><strong>通用性</strong>：支持所有基于 TCP 或 UDP 的协议。</li>
<li><strong>流量透传</strong>：直接传递 TCP/UDP 流量，保持数据的原始状态。</li>
<li><strong>简单的健康检查</strong>：通过检查 TCP 端口是否能接受连接来判断后端服务的健康状态。</li>
<li><strong>SSL/TLS 穿透</strong>：实现 SSL/TLS 穿透，即直接将加密的流量转发给后端的 SSL/TLS 终点。</li>
<li><strong>高效率</strong>：因为不需要处理复杂的应用层内容，所以转发效率高于七层负载均衡。</li>
</ul>
<h4 id="配置示例-1">配置示例<a role="anchor" aria-hidden="true" tabindex="-1" data-no-popover="true" href="#配置示例-1" class="internal"><svg width="18" height="18" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><path d="M10 13a5 5 0 0 0 7.54.54l3-3a5 5 0 0 0-7.07-7.07l-1.72 1.71"></path><path d="M14 11a5 5 0 0 0-7.54-.54l-3 3a5 5 0 0 0 7.07 7.07l1.71-1.71"></path></svg></a></h4>
<figure data-rehype-pretty-code-figure><pre tabindex="0" data-language="nginx" data-theme="github-light github-dark"><code data-language="nginx" data-theme="github-light github-dark" style="display:grid;"><span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">stream</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> {</span></span>
<span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> upstream</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> myapp_tcp </span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">{</span></span>
<span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> server</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> backend1.example.com:1234;</span></span>
<span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> server</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> backend2.example.com:1234;</span></span>
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> }</span></span>
<span data-line> </span>
<span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> server</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> {</span></span>
<span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> listen </span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">1234</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">;</span></span>
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> </span></span>
<span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> proxy_pass </span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">myapp_tcp;</span></span>
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> }</span></span>
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">}</span></span></code></pre></figure>
<h3 id="内置策略">内置策略<a role="anchor" aria-hidden="true" tabindex="-1" data-no-popover="true" href="#内置策略" class="internal"><svg width="18" height="18" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><path d="M10 13a5 5 0 0 0 7.54.54l3-3a5 5 0 0 0-7.07-7.07l-1.72 1.71"></path><path d="M14 11a5 5 0 0 0-7.54-.54l-3 3a5 5 0 0 0 7.07 7.07l1.71-1.71"></path></svg></a></h3>
<h4 id="轮询">轮询<a role="anchor" aria-hidden="true" tabindex="-1" data-no-popover="true" href="#轮询" class="internal"><svg width="18" height="18" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><path d="M10 13a5 5 0 0 0 7.54.54l3-3a5 5 0 0 0-7.07-7.07l-1.72 1.71"></path><path d="M14 11a5 5 0 0 0-7.54-.54l-3 3a5 5 0 0 0 7.07 7.07l1.71-1.71"></path></svg></a></h4>
<p><strong>默认策略</strong>，按时间顺序逐一分配到不同的后端服务器，如果后端服务挂了，能自动剔除。</p>
<figure data-rehype-pretty-code-figure><pre tabindex="0" data-language="nginx" data-theme="github-light github-dark"><code data-language="nginx" data-theme="github-light github-dark" style="display:grid;"><span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">upstream</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> backend </span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">{</span></span>
<span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> server</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> 127.0.0.1:3000;</span></span>
<span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> server</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> 127.0.0.1:3001;</span></span>
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">}</span></span></code></pre></figure>
<h4 id="加权轮询">加权轮询<a role="anchor" aria-hidden="true" tabindex="-1" data-no-popover="true" href="#加权轮询" class="internal"><svg width="18" height="18" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><path d="M10 13a5 5 0 0 0 7.54.54l3-3a5 5 0 0 0-7.07-7.07l-1.72 1.71"></path><path d="M14 11a5 5 0 0 0-7.54-.54l-3 3a5 5 0 0 0 7.07 7.07l1.71-1.71"></path></svg></a></h4>
<p>与轮询相似，但可以指定权重，<code>weight</code> 值越大，分配到的访问几率越高。</p>
<figure data-rehype-pretty-code-figure><pre tabindex="0" data-language="nginx" data-theme="github-light github-dark"><code data-language="nginx" data-theme="github-light github-dark" style="display:grid;"><span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">upstream</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> backend </span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">{</span></span>
<span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> server</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> 127.0.0.1:3000 </span><span style="--shiki-light:#E36209;--shiki-dark:#FFAB70;">weight</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">2</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">;</span></span>
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> server 127.0.0.1:3001 </span><span style="--shiki-light:#E36209;--shiki-dark:#FFAB70;">weight</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">1</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">;</span></span>
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">}</span></span></code></pre></figure>
<h4 id="关键值-hash">关键值 Hash<a role="anchor" aria-hidden="true" tabindex="-1" data-no-popover="true" href="#关键值-hash" class="internal"><svg width="18" height="18" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><path d="M10 13a5 5 0 0 0 7.54.54l3-3a5 5 0 0 0-7.07-7.07l-1.72 1.71"></path><path d="M14 11a5 5 0 0 0-7.54-.54l-3 3a5 5 0 0 0 7.07 7.07l1.71-1.71"></path></svg></a></h4>
<p>自定义 key（如 IP 地址、请求头、cookie 等）作为 hash 的依据，决定请求应该转发到哪个服务器。</p>
<figure data-rehype-pretty-code-figure><pre tabindex="0" data-language="nginx" data-theme="github-light github-dark"><code data-language="nginx" data-theme="github-light github-dark" style="display:grid;"><span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">upstream</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> backend </span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">{</span></span>
<span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> hash </span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">$remote_addr; </span><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;"># 使用客户端IP地址作为hash键值</span></span>
<span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> server</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> 127.0.0.1:3000;</span></span>
<span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> server</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> 127.0.0.1:3001;</span></span>
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">}</span></span></code></pre></figure>
<h4 id="ip_hash">ip_hash<a role="anchor" aria-hidden="true" tabindex="-1" data-no-popover="true" href="#ip_hash" class="internal"><svg width="18" height="18" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><path d="M10 13a5 5 0 0 0 7.54.54l3-3a5 5 0 0 0-7.07-7.07l-1.72 1.71"></path><path d="M14 11a5 5 0 0 0-7.54-.54l-3 3a5 5 0 0 0 7.07 7.07l1.71-1.71"></path></svg></a></h4>
<p>每个请求按访问 IP 的 hash 结果分配，可以解决动态网页 session 共享问题。</p>
<figure data-rehype-pretty-code-figure><pre tabindex="0" data-language="nginx" data-theme="github-light github-dark"><code data-language="nginx" data-theme="github-light github-dark" style="display:grid;"><span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">upstream</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> backend </span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">{</span></span>
<span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> ip_hash</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">;</span></span>
<span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> server</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> 127.0.0.1:3000;</span></span>
<span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> server</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> 127.0.0.1:3001;</span></span>
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">}</span></span></code></pre></figure>
<h4 id="least_conn">least_conn<a role="anchor" aria-hidden="true" tabindex="-1" data-no-popover="true" href="#least_conn" class="internal"><svg width="18" height="18" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><path d="M10 13a5 5 0 0 0 7.54.54l3-3a5 5 0 0 0-7.07-7.07l-1.72 1.71"></path><path d="M14 11a5 5 0 0 0-7.54-.54l-3 3a5 5 0 0 0 7.07 7.07l1.71-1.71"></path></svg></a></h4>
<p>最少连接数策略，那个机器连接数少就分配到那个机器，适用于处理长时间运行的连接。</p>
<figure data-rehype-pretty-code-figure><pre tabindex="0" data-language="nginx" data-theme="github-light github-dark"><code data-language="nginx" data-theme="github-light github-dark" style="display:grid;"><span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">upstream</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> backend </span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">{</span></span>
<span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> least_conn</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">;</span></span>
<span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> server</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> 127.0.0.1:3000;</span></span>
<span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> server</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> 127.0.0.1:3001;</span></span>
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">}</span></span></code></pre></figure>
<h3 id="配置选项">配置选项<a role="anchor" aria-hidden="true" tabindex="-1" data-no-popover="true" href="#配置选项" class="internal"><svg width="18" height="18" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><path d="M10 13a5 5 0 0 0 7.54.54l3-3a5 5 0 0 0-7.07-7.07l-1.72 1.71"></path><path d="M14 11a5 5 0 0 0-7.54-.54l-3 3a5 5 0 0 0 7.07 7.07l1.71-1.71"></path></svg></a></h3>
<div class="table-container"><table><thead><tr><th>配置选项</th><th>描述</th><th>语句示例</th></tr></thead><tbody><tr><td>backup</td><td>标记服务器为备份服务器，仅在主服务器不可用时使用</td><td><code>upstream backend { server server1; server server2 backup; }</code></td></tr><tr><td>down</td><td>标记服务器为永久离线状态</td><td><code>upstream backend { server server1 down; server server2; }</code></td></tr><tr><td>max_fails</td><td>允许请求失败的次数，默认为 1</td><td><code>upstream backend { server server1 max_fails=3 fail_timeout=30s; }</code></td></tr><tr><td>fail_timeout</td><td>经过 max_fails 失败后，服务暂停的时间</td><td>同上，通常与 max_fails 一起配置</td></tr><tr><td>weight</td><td>设置服务器的权重，默认为 1</td><td><code>upstream backend { server server1 weight=2; server server2; }</code></td></tr><tr><td>max_conns</td><td>限制最大的接收的连接数</td><td><code>upstream backend { server server1 max_conns=100; }</code></td></tr></tbody></table></div>
<h3 id="常见示例">常见示例<a role="anchor" aria-hidden="true" tabindex="-1" data-no-popover="true" href="#常见示例" class="internal"><svg width="18" height="18" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><path d="M10 13a5 5 0 0 0 7.54.54l3-3a5 5 0 0 0-7.07-7.07l-1.72 1.71"></path><path d="M14 11a5 5 0 0 0-7.54-.54l-3 3a5 5 0 0 0 7.07 7.07l1.71-1.71"></path></svg></a></h3>
<figure data-rehype-pretty-code-figure><pre tabindex="0" data-language="nginx" data-theme="github-light github-dark"><code data-language="nginx" data-theme="github-light github-dark" style="display:grid;"><span data-line><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;"># 基本的加权和备份服务器配置</span></span>
<span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">upstream</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> backend </span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">{</span></span>
<span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> server</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> 127.0.0.1:3000 </span><span style="--shiki-light:#E36209;--shiki-dark:#FFAB70;">weight</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">3</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">;</span></span>
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> server 127.0.0.1:3001 </span><span style="--shiki-light:#E36209;--shiki-dark:#FFAB70;">weight</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">2</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">;</span></span>
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> server 127.0.0.1:3002 backup; </span><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;"># 备份服务器</span></span>
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">}</span></span>
<span data-line> </span>
<span data-line><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;"># 组合健康检查和备份</span></span>
<span data-line><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;"># 当它们连续失败超过max_fails次后，在fail_timeout时间内被认为是不可用的。</span></span>
<span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">upstream</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> backend </span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">{</span></span>
<span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> server</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> 127.0.0.1:3000 </span><span style="--shiki-light:#E36209;--shiki-dark:#FFAB70;">max_fails</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">2</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> fail_timeout=30s;</span></span>
<span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> server</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> 127.0.0.1:3001 </span><span style="--shiki-light:#E36209;--shiki-dark:#FFAB70;">max_fails</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">2</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> fail_timeout=30s;</span></span>
<span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> server</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> 127.0.0.1:3002 backup; </span><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;"># 备份服务器</span></span>
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">}</span></span>
<span data-line> </span>
<span data-line><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;"># 使用权重、连接数限制和离线状态</span></span>
<span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">upstream</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> backend </span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">{</span></span>
<span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> server</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> 127.0.0.1:3000 </span><span style="--shiki-light:#E36209;--shiki-dark:#FFAB70;">weight</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">3</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> max_conns=100;</span></span>
<span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> server</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> 127.0.0.1:3001 </span><span style="--shiki-light:#E36209;--shiki-dark:#FFAB70;">weight</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">2</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> max_conns=150;</span></span>
<span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> server</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> 127.0.0.1:3002 down; </span><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;"># 暂时离线的服务器</span></span>
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">}</span></span>
<span data-line> </span>
<span data-line><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;"># 综合使用所有配置</span></span>
<span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">upstream</span><span style="--shiki-light:#6F42C1;--shiki-dark:#B392F0;"> backend </span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">{</span></span>
<span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> server</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> 127.0.0.1:3000 </span><span style="--shiki-light:#E36209;--shiki-dark:#FFAB70;">weight</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">3</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> max_fails=2 </span><span style="--shiki-light:#E36209;--shiki-dark:#FFAB70;">fail_timeout</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">30s</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> max_conns=100;</span></span>
<span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> server</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> 127.0.0.1:3001 </span><span style="--shiki-light:#E36209;--shiki-dark:#FFAB70;">weight</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">2</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> max_fails=2 </span><span style="--shiki-light:#E36209;--shiki-dark:#FFAB70;">fail_timeout</span><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;">=</span><span style="--shiki-light:#005CC5;--shiki-dark:#79B8FF;">30s</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> max_conns=150;</span></span>
<span data-line><span style="--shiki-light:#D73A49;--shiki-dark:#F97583;"> server</span><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;"> 127.0.0.1:3002 backup; </span><span style="--shiki-light:#6A737D;--shiki-dark:#6A737D;"># 备份服务器</span></span>
<span data-line><span style="--shiki-light:#24292E;--shiki-dark:#E1E4E8;">}</span></span></code></pre></figure></article><hr/><div class="page-footer"></div></div><div class="right sidebar"><div class="graph"><h3>关系图谱</h3><div class="graph-outer"><div id="graph-container" data-cfg="{&quot;drag&quot;:true,&quot;zoom&quot;:true,&quot;depth&quot;:1,&quot;scale&quot;:1.1,&quot;repelForce&quot;:0.5,&quot;centerForce&quot;:0.3,&quot;linkDistance&quot;:30,&quot;fontSize&quot;:0.6,&quot;opacityScale&quot;:1,&quot;showTags&quot;:true,&quot;removeTags&quot;:[],&quot;focusOnHover&quot;:false}"></div><button id="global-graph-icon" aria-label="Global Graph"><svg version="1.1" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" x="0px" y="0px" viewBox="0 0 55 55" fill="currentColor" xml:space="preserve"><path d="M49,0c-3.309,0-6,2.691-6,6c0,1.035,0.263,2.009,0.726,2.86l-9.829,9.829C32.542,17.634,30.846,17,29,17
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