300 lines
10 KiB
Markdown
300 lines
10 KiB
Markdown
# Envoy 作为前端代理
|
||
|
||
本文是使用 Envoy 作为前端代理的介绍，仅使用 docker 容器和 docker-compose 做编排在单机中运行，帮助我们从更底层了解 Envoy，当我们将 Envoy 作为 Istio Service Mesh 的 data panel 的时候将更加游刃有余。
|
||
|
||
## 快速开始
|
||
|
||
Envoy 中的所有规则配置跟 Kubernetes 一样都是通过 YAML 文件来完成的。在继续下面的步骤之前，首先克隆 Envoy 的 GitHub repo。
|
||
|
||
```bash
|
||
git clone https://github.com/envoyproxy/envoy.git
|
||
```
|
||
|
||
## 运行 sandbox 测试
|
||
|
||
Envoy 官方提供了以下打包用例：
|
||
|
||
- [Front Proxy](https://www.envoyproxy.io/docs/envoy/latest/start/sandboxes/front_proxy)
|
||
- [Zipkin Tracing](https://www.envoyproxy.io/docs/envoy/latest/start/sandboxes/zipkin_tracing)
|
||
- [Jaeger Tracing](https://www.envoyproxy.io/docs/envoy/latest/start/sandboxes/jaeger_tracing)
|
||
- [gRPC Bridge](https://www.envoyproxy.io/docs/envoy/latest/start/sandboxes/grpc_bridge)
|
||
|
||
全部可以使用 `docker-compose` 运行，代码可以在 [GitHub](https://github.com/envoyproxy/envoy/tree/master/examples) 找到。
|
||
|
||
## Front proxy
|
||
|
||
Envoy 在 Envoy mesh 的边缘做反向代理，详细使用方式见 [Envoy 文档](https://www.envoyproxy.io/docs/envoy/latest/start/sandboxes/front_proxy)，在此我将解说下以下问题：
|
||
|
||
- Envoy 是如何作为进程外架构运行的？
|
||
- 为何说 Envoy 是无侵入式架构？
|
||
- Envoy 作为边缘反向代理能做什么？
|
||
|
||
本示例的架构图如下所示，此时 Envoy 将作为一个反向代理，类似于 Nginx，但与 Nginx 不同的是它还会作为一个进程，伴随每个服务一起运行在同一个容器中（在 Kubernetes 中可以作为 Sidecar 与应用容器一起运行在同一个 Pod 中）。
|
||
|
||
|
||
|
||
在此示例中一共有 3 个服务，我们需要为其创建容器编排的 `docker-compose.yml` 文件。
|
||
|
||
```yaml
|
||
version: '2'
|
||
services:
|
||
|
||
front-envoy:
|
||
build:
|
||
context: .
|
||
dockerfile: Dockerfile-frontenvoy
|
||
volumes:
|
||
- ./front-envoy.yaml:/etc/front-envoy.yaml
|
||
networks:
|
||
- envoymesh
|
||
expose:
|
||
- "80"
|
||
- "8001"
|
||
ports:
|
||
- "8000:80"
|
||
- "8001:8001"
|
||
|
||
service1:
|
||
build:
|
||
context: .
|
||
dockerfile: Dockerfile-service
|
||
volumes:
|
||
- ./service-envoy.yaml:/etc/service-envoy.yaml
|
||
networks:
|
||
envoymesh:
|
||
aliases:
|
||
- service1
|
||
environment:
|
||
- SERVICE_NAME=1
|
||
expose:
|
||
- "80"
|
||
|
||
service2:
|
||
build:
|
||
context: .
|
||
dockerfile: Dockerfile-service
|
||
volumes:
|
||
- ./service-envoy.yaml:/etc/service-envoy.yaml
|
||
networks:
|
||
envoymesh:
|
||
aliases:
|
||
- service2
|
||
environment:
|
||
- SERVICE_NAME=2
|
||
expose:
|
||
- "80"
|
||
|
||
networks:
|
||
envoymesh: {}
|
||
```
|
||
|
||
使用 docker-compose 启动可以保证三个服务都在同一个网络内，即 `frontproxy_envoymesh` 网络中。
|
||
|
||
其中 `front-envoy` 是前端（边缘）Envoy 服务，用来做反向代理，它使用的是 `Dockerfile-frontenvoy` 文件来构建镜像的，我们来看下该 `Dockerfile` 的内容。
|
||
|
||
```docker
|
||
FROM envoyproxy/envoy:latest
|
||
|
||
RUN apt-get update && apt-get -q install -y \
|
||
curl
|
||
CMD /usr/local/bin/envoy -c /etc/front-envoy.yaml --service-cluster front-proxy
|
||
```
|
||
|
||
其中 `/etc/front-envoy.yaml` 是本地的 `front-envoy.yaml` 挂载进去的。我们看下该文件的内容。
|
||
|
||
```yaml
|
||
static_resources:
|
||
listeners:
|
||
- address:
|
||
socket_address:
|
||
address: 0.0.0.0
|
||
port_value: 80
|
||
filter_chains:
|
||
- filters:
|
||
- name: envoy.http_connection_manager
|
||
config:
|
||
codec_type: auto
|
||
stat_prefix: ingress_http
|
||
route_config:
|
||
name: local_route
|
||
virtual_hosts:
|
||
- name: backend
|
||
domains:
|
||
- "*"
|
||
routes:
|
||
- match:
|
||
prefix: "/service/1"
|
||
route:
|
||
cluster: service1
|
||
- match:
|
||
prefix: "/service/2"
|
||
route:
|
||
cluster: service2
|
||
http_filters:
|
||
- name: envoy.router
|
||
config: {}
|
||
clusters:
|
||
- name: service1
|
||
connect_timeout: 0.25s
|
||
type: strict_dns
|
||
lb_policy: round_robin
|
||
http2_protocol_options: {}
|
||
hosts:
|
||
- socket_address:
|
||
address: service1
|
||
port_value: 80
|
||
- name: service2
|
||
connect_timeout: 0.25s
|
||
type: strict_dns
|
||
lb_policy: round_robin
|
||
http2_protocol_options: {}
|
||
hosts:
|
||
- socket_address:
|
||
address: service2
|
||
port_value: 80
|
||
admin:
|
||
access_log_path: "/dev/null"
|
||
address:
|
||
socket_address:
|
||
address: 0.0.0.0
|
||
port_value: 8001
|
||
```
|
||
|
||
我们看到其中包括了三大配置项：
|
||
|
||
- **static_resources**：路由配置信息
|
||
- **cluster**：envoymesh 的服务注册信息
|
||
- **admin**：管理接口，可以通过访问 8001 端口的，访问 `/stats` 获取当前 envoymesh 的一些统计信息，访问 `/server_info` 获取 Envoy 的版本信息
|
||
|
||
使用 `docker-compose` 启动三个容器。
|
||
|
||
```bash
|
||
$ 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
|
||
```
|
||
|
||
我们下面将过一遍 Envoy 作为前端代理的所有功能，这些功能是通用功能。
|
||
|
||
### 路由
|
||
|
||
访问 service1 <http://localhost:8000/service/1> 将看到如下输出。
|
||
|
||
```bash
|
||
$ curl -v localhost:8000/service/1
|
||
*
|
||
Trying ::1...
|
||
* TCP_NODELAY set
|
||
* Connected to localhost (::1) port 8000 (#0)
|
||
> GET /service/1 HTTP/1.1
|
||
> Host: localhost:8000
|
||
> User-Agent: curl/7.54.0
|
||
> Accept: */*
|
||
>
|
||
< HTTP/1.1 200 OK
|
||
< content-type: text/html; charset=utf-8
|
||
< content-length: 89
|
||
< server: envoy
|
||
< date: Fri, 20 Apr 2018 08:26:33 GMT
|
||
< x-envoy-upstream-service-time: 14
|
||
<
|
||
Hello from behind Envoy (service 1)! hostname: a3e4185a9a49 resolvedhostname: 172.18.0.4
|
||
* Connection #0 to host localhost left intact
|
||
```
|
||
|
||
访问 service2 <http://localhost:8000/service/2> 将看到如下输出。
|
||
|
||
```bash
|
||
* Trying ::1...
|
||
* TCP_NODELAY set
|
||
* Connected to localhost (::1) port 8000 (#0)
|
||
> GET /service/2 HTTP/1.1
|
||
> Host: localhost:8000
|
||
> User-Agent: curl/7.54.0
|
||
> Accept: */*
|
||
>
|
||
< HTTP/1.1 200 OK
|
||
< content-type: text/html; charset=utf-8
|
||
< content-length: 89
|
||
< server: envoy
|
||
< date: Fri, 20 Apr 2018 08:27:27 GMT
|
||
< x-envoy-upstream-service-time: 10
|
||
<
|
||
Hello from behind Envoy (service 2)! hostname: f6650e1911a0 resolvedhostname: 172.18.0.3
|
||
* Connection #0 to host localhost left intact
|
||
```
|
||
|
||
我们看到访问请求被路由到了正确的服务后端。
|
||
|
||
### 负载均衡
|
||
|
||
增加 service1 的示例数。
|
||
|
||
```bash
|
||
$ docker-compose scale service1=3
|
||
WARNING: The scale command is deprecated. Use the up command with the --scale flag instead.
|
||
Starting frontproxy_service1_1 ... done
|
||
Creating frontproxy_service1_2 ... done
|
||
Creating frontproxy_service1_3 ... done
|
||
|
||
$ docker-compose ps
|
||
Name Command State Ports
|
||
---------------------------------------------------------------------------------------------------------------------------
|
||
frontproxy_front-envoy_1 /usr/bin/dumb-init -- /bin ... Up 10000/tcp, 0.0.0.0:8000->80/tcp, 0.0.0.0:8001->8001/tcp
|
||
frontproxy_service1_1 /bin/sh -c /usr/local/bin/ ... Up 10000/tcp, 80/tcp
|
||
frontproxy_service1_2 /bin/sh -c /usr/local/bin/ ... Up 10000/tcp, 80/tcp
|
||
frontproxy_service1_3 /bin/sh -c /usr/local/bin/ ... Up 10000/tcp, 80/tcp
|
||
frontproxy_service2_1 /bin/sh -c /usr/local/bin/ ... Up 10000/tcp, 80/tcp
|
||
```
|
||
|
||
我们看到现在 service1 已经有了 3 个实例，现在再访问 service1 <http://localhost:8000/service/1>。
|
||
|
||
```bash
|
||
$ while true;do curl localhost:8000/service/1;sleep 1;done
|
||
Hello from behind Envoy (service 1)! hostname: a3e4185a9a49 resolvedhostname: 172.18.0.4
|
||
Hello from behind Envoy (service 1)! hostname: fe44dba64122 resolvedhostname: 172.18.0.5
|
||
Hello from behind Envoy (service 1)! hostname: c5b9f1289e0f resolvedhostname: 172.18.0.6
|
||
Hello from behind Envoy (service 1)! hostname: a3e4185a9a49 resolvedhostname: 172.18.0.4
|
||
Hello from behind Envoy (service 1)! hostname: fe44dba64122 resolvedhostname: 172.18.0.5
|
||
Hello from behind Envoy (service 1)! hostname: c5b9f1289e0f resolvedhostname: 172.18.0.6
|
||
```
|
||
|
||
我们看到对 service1 的已经有负载均衡了，使用的策略是 `round_robin`，这些都是在 `front-envoy.yaml` 文件中的 `cluster` 项下配置的。
|
||
|
||
### admin 端点
|
||
|
||
访问 <http://localhost:8001> 可以看到 Envoy admin 提供以下管理 API 端点。
|
||
|
||
| 命令 | 描述 |
|
||
| -------------------- | ---------------------------------------- |
|
||
| / | Admin 主页 |
|
||
| /certs | 打印机器上的 certs |
|
||
| /clusters | upstream cluster 状态 |
|
||
| /config_dump | 输出当前的 Envoy 配置 |
|
||
| /cpuprofiler | 开启/关闭 CPU profiler |
|
||
| /healthcheck/fail | 导致服务失败健康检查 |
|
||
| /healthcheck/ok | 导致服务通过健康检查 |
|
||
| /help | 打印管理命令的帮助信息 |
|
||
| /hot_restart_version | 打印热重启兼容版本 |
|
||
| /listeners | 打印 listener 地址 |
|
||
| /logging | 查询/更改日志级别 |
|
||
| /quitquitquit | 退出服务 |
|
||
| /reset_counters | 将计数器重置为 1 |
|
||
| /runtime | 打印运行时值 |
|
||
| /runtime_modify | 修改运行时值 |
|
||
| /server_info | 打印服务器版本/状态信息 |
|
||
| /stats | 打印服务器状态统计信息 |
|
||
| /stats/prometheus | 打印 prometheus 格式的服务器状态统计信息 |
|
||
|
||
Envoy 提供了 API 管理端点，可以对 Envoy 进行动态配置。
|
||
|
||
## 参考
|
||
|
||
- [Front proxy - envoyproxy.io](https://www.envoyproxy.io/docs/envoy/latest/start/sandboxes/front_proxy)
|