# 前端代理

## 前端代理

为让大家尽快了解Envoy如何作为前端代理，我们发布了一个[docker compose](https://docs.docker.com/compose/)沙箱，这个沙箱部署了一个前端Envoy代理和几个后端服务（简单的flask应用），并与一个正在运行的合作的Envoy服务。这三个容器将部署在名为`envoymesh`的虚拟网格中。

该Docker compose的部署图如下所示：

![部署图](/files/-LlnozGN7vx2sQFien4l)

所有传入的请求都通过前端Envoy进行路由，该Envoy充当位于`envoymesh`网络边缘的反向代理。端口`80`通过docker compose映射到端口`8000`（请参阅[/examples/front-proxy/docker-compose.yml](https://github.com/envoyproxy/envoy/blob/master//examples/front-proxy/docker-compose.yml)）。此外，请注意，由前端Envoy路由到容器内的服务，实际上所有流量都是路由到服务的Envoy代理（在[/examples/front-proxy/front-envoy.json](https://github.com/envoyproxy/envoy/blob/master//examples/front-proxy/front-envoy.json)中设置的路由）。反过来，服务的Envoy通过环回地址（[/examples/front-proxy/service-envoy.json](https://github.com/envoyproxy/envoy/blob/master//examples/front-proxy/service-envoy.json)中的路由设置）将请求路由到flask应用程序。此阐述了Envoy与您服务搭配的优势：所有请求都由Envoy代理，并有效地路由到您的服务。

### 运行沙箱

以下文档将按照上图中所述的envoy集群进行运行设置。

**第1步：安装Docker工具集**

请您确保已经安装了最新版本的`docker`，`docker-compose`和`docker-machine`。

[Docker工具箱](https://www.docker.com/products/docker-toolbox)提供了简单的方法来获取这些工具。

**第2步：设置Docker Machine**

首先让我们创建一个新的机器来容纳容器：

```
$ docker-machine create --driver virtualbox default
$ eval $(docker-machine env default)
```

**第3步：建立本地Envoy克隆仓库，并启动所有的容器**

如果你还没有克隆Envoy仓库，请用git克隆`git clone git@github.com:envoyproxy/envoy`或者`git clone https://github.com/envoyproxy/envoy.git`：

```
$ pwd
envoy/examples/front-proxy
$ docker-compose up --build -d
$ docker-compose ps
        Name                       Command               State      Ports
-------------------------------------------------------------------------------------------------------------
example_service1_1      /bin/sh -c /usr/local/bin/ ...    Up       80/tcp
example_service2_1      /bin/sh -c /usr/local/bin/ ...    Up       80/tcp
example_front-envoy_1   /bin/sh -c /usr/local/bin/ ...    Up       0.0.0.0:8000->80/tcp, 0.0.0.0:8001->8001/tcp
```

**第4步：测试Envoy的路由功能**

您现在可以通过前端Envoy向两个服务发送请求。

对于service1：

```
$ curl -v $(docker-machine ip default):8000/service/1
*   Trying 192.168.99.100...
* Connected to 192.168.99.100 (192.168.99.100) port 8000 (#0)
> GET /service/1 HTTP/1.1
> Host: 192.168.99.100:8000
> User-Agent: curl/7.43.0
> Accept: */*
>
< HTTP/1.1 200 OK
< content-type: text/html; charset=utf-8
< content-length: 89
< x-envoy-upstream-service-time: 1
< server: envoy
< date: Fri, 26 Aug 2016 19:39:19 GMT
< x-envoy-protocol-version: HTTP/1.1
<
Hello from behind Envoy (service 1)! hostname: f26027f1ce28 resolvedhostname: 172.19.0.6
* Connection #0 to host 192.168.99.100 left intact
```

对于service2：

```
$ curl -v $(docker-machine ip default):8000/service/2
*   Trying 192.168.99.100...
* Connected to 192.168.99.100 (192.168.99.100) port 8000 (#0)
> GET /service/2 HTTP/1.1
> Host: 192.168.99.100:8000
> User-Agent: curl/7.43.0
> Accept: */*
>
< HTTP/1.1 200 OK
< content-type: text/html; charset=utf-8
< content-length: 89
< x-envoy-upstream-service-time: 2
< server: envoy
< date: Fri, 26 Aug 2016 19:39:23 GMT
< x-envoy-protocol-version: HTTP/1.1
<
Hello from behind Envoy (service 2)! hostname: 92f4a3737bbc resolvedhostname: 172.19.0.2
* Connection #0 to host 192.168.99.100 left intact
```

请注意，每个请求在发送给前端Envoy时，已正确路由到相应的应用程序。

**第5步：测试Envoy的负载均衡能力**

现在扩展我们的service1节点来演示Envoy的集群能力。

```
$ docker-compose scale service1=3
Creating and starting example_service1_2 ... done
Creating and starting example_service1_3 ... done
```

现在，如果我们多次向service1发送请求，前端Envoy会将请求通过负载均衡发给三个service1服务：

```
$ curl -v $(docker-machine ip default):8000/service/1
*   Trying 192.168.99.100...
* Connected to 192.168.99.100 (192.168.99.100) port 8000 (#0)
> GET /service/1 HTTP/1.1
> Host: 192.168.99.100:8000
> User-Agent: curl/7.43.0
> Accept: */*
>
< HTTP/1.1 200 OK
< content-type: text/html; charset=utf-8
< content-length: 89
< x-envoy-upstream-service-time: 1
< server: envoy
< date: Fri, 26 Aug 2016 19:40:21 GMT
< x-envoy-protocol-version: HTTP/1.1
<
Hello from behind Envoy (service 1)! hostname: 85ac151715c6 resolvedhostname: 172.19.0.3
* Connection #0 to host 192.168.99.100 left intact
$ curl -v $(docker-machine ip default):8000/service/1
*   Trying 192.168.99.100...
* Connected to 192.168.99.100 (192.168.99.100) port 8000 (#0)
> GET /service/1 HTTP/1.1
> Host: 192.168.99.100:8000
> User-Agent: curl/7.43.0
> Accept: */*
>
< HTTP/1.1 200 OK
< content-type: text/html; charset=utf-8
< content-length: 89
< x-envoy-upstream-service-time: 1
< server: envoy
< date: Fri, 26 Aug 2016 19:40:22 GMT
< x-envoy-protocol-version: HTTP/1.1
<
Hello from behind Envoy (service 1)! hostname: 20da22cfc955 resolvedhostname: 172.19.0.5
* Connection #0 to host 192.168.99.100 left intact
$ curl -v $(docker-machine ip default):8000/service/1
*   Trying 192.168.99.100...
* Connected to 192.168.99.100 (192.168.99.100) port 8000 (#0)
> GET /service/1 HTTP/1.1
> Host: 192.168.99.100:8000
> User-Agent: curl/7.43.0
> Accept: */*
>
< HTTP/1.1 200 OK
< content-type: text/html; charset=utf-8
< content-length: 89
< x-envoy-upstream-service-time: 1
< server: envoy
< date: Fri, 26 Aug 2016 19:40:24 GMT
< x-envoy-protocol-version: HTTP/1.1
<
Hello from behind Envoy (service 1)! hostname: f26027f1ce28 resolvedhostname: 172.19.0.6
* Connection #0 to host 192.168.99.100 left intact
```

**第6步：进入容器开启curl服务**

除了使用主机上的curl外，您还可以自己输入容器并从里面curl。要输入一个容器镜像，你可以使用`docker-compose exec <container_name> /bin/bash`。例如，我们可以进入`front-envoy`容器，并在执行本地的curl服务：

```
$ docker-compose exec front-envoy /bin/bash
root@81288499f9d7:/# curl localhost:80/service/1
Hello from behind Envoy (service 1)! hostname: 85ac151715c6 resolvedhostname: 172.19.0.3
root@81288499f9d7:/# curl localhost:80/service/1
Hello from behind Envoy (service 1)! hostname: 20da22cfc955 resolvedhostname: 172.19.0.5
root@81288499f9d7:/# curl localhost:80/service/1
Hello from behind Envoy (service 1)! hostname: f26027f1ce28 resolvedhostname: 172.19.0.6
root@81288499f9d7:/# curl localhost:80/service/2
Hello from behind Envoy (service 2)! hostname: 92f4a3737bbc resolvedhostname: 172.19.0.2
```

**第7步：进入容器和使用curl管理**

当Envoy运行时，它也将`admin`连接到所需的端口。在示例配置`admin`被绑定到`8001`端口.我们可以`curl`它获得有用的信息。例如，您可以`curl` `/server_info`来获取有关您正在运行的Envoy版本信息。另外，你可以·curl· ·/stats·得到统计数据。例如在`frontenvoy`里面我们可以得到：

```
$ docker-compose exec front-envoy /bin/bash
root@e654c2c83277:/# curl localhost:8001/server_info
envoy 10e00b/RELEASE live 142 142 0
root@e654c2c83277:/# curl localhost:8001/stats
cluster.service1.external.upstream_rq_200: 7
...
cluster.service1.membership_change: 2
cluster.service1.membership_total: 3
...
cluster.service1.upstream_cx_http2_total: 3
...
cluster.service1.upstream_rq_total: 7
...
cluster.service2.external.upstream_rq_200: 2
...
cluster.service2.membership_change: 1
cluster.service2.membership_total: 1
...
cluster.service2.upstream_cx_http2_total: 1
...
cluster.service2.upstream_rq_total: 2
...
```

请注意，我们还可以获得上游群集的成员数量，完成的请求数量，有关http入站的信息以及其他大量有用的统计信息。

## 返回

* [上一级](/envoy/buildingandinstallation/sandboxes.md)
* [首页目录](/envoy/master.md)


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://lixiangyun.gitbook.io/envoy/buildingandinstallation/sandboxes/frontproxy.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.