流量编排系统Easegress初探

Easegress是一个开源的流量编排系统（An all-rounder traffic orchestration system），居官方介绍这个系统通过Raft共识算法（实际上就是etcd）提供了分布式情况下的高可用、可以实现流量API调度、支持高并发高性能场景；

当然在我体验之后发现其实这个系统最特别的地方（与传统Nginx相比）在于Easegress是通过插件的方式直接进行热替换进行的（如果你使用过K8S，对于这种方式应该不会陌生）；

本文介绍了Easegress的基本用法；

源代码：

• https://github.com/JasonkayZK/Go_Learn/tree/easegress-demo

流量编排系统Easegress初探

安装Easegress

Easegress的安装可以说是相当简单了；

其实就是两个二进制文件：

• easegress-server
• egctl

可以直接通过下载仓库的Release安装：

• https://github.com/megaease/easegress/releases/tag/v1.0.0

下载后解压，然后将二进制直接放入$PATH$环境变量即可；

当然，也可以通过编译源码安装，这里不作介绍了；

启动服务器

启动服务器非常简单，我们可以直接使用默认参数启动：

[root@localhost easegress]# easegress-server 
WARNING: Package "github.com/golang/protobuf/protoc-gen-go/generator" is deprecated.
        A future release of golang/protobuf will delete this package,
        which has long been excluded from the compatibility promise.

2021-06-13T09:47:09.205+08:00   INFO    server/main.go:61       Easegress release: v1.0.0, repo: megaease/easegress, commit: 3dd74e5b01d0852ed5dffe03de9b4d48a64667e7
2021-06-13T09:47:09.205+08:00   INFO    storage/storage.go:250  /root/workspace/easegress/running_objects.yaml not exist
2021-06-13T09:47:09.205+08:00   INFO    cluster/cluster.go:186  starting etcd cluster
2021-06-13T09:47:09.205+08:00   INFO    cluster/cluster.go:382  client connect with endpoints: [http://localhost:2380]
2021-06-13T09:47:09.205+08:00   INFO    cluster/config.go:126   etcd config: init-cluster:eg-default-name=http://localhost:2380 cluster-state:new force-new-cluster:false
2021-06-13T09:47:09.206+08:00   INFO    cluster/cluster.go:396  client is ready
2021-06-13T09:47:09.733+08:00   INFO    cluster/cluster.go:607  server is ready
2021-06-13T09:47:09.734+08:00   INFO    cluster/cluster.go:468  lease is ready
2021-06-13T09:47:09.734+08:00   INFO    cluster/cluster.go:204  cluster is ready
2021-06-13T09:47:09.763+08:00   INFO    storage/storage.go:250  /root/workspace/easegress/running_objects.yaml not exist
2021-06-13T09:47:09.764+08:00   INFO    supervisor/supervisor.go:197    create system controller StatusSyncController
2021-06-13T09:47:09.764+08:00   INFO    cluster/cluster.go:513  session is ready
2021-06-13T09:47:09.765+08:00   INFO    api/api.go:113  api server running in localhost:2381
2021-06-13T09:47:14.738+08:00   INFO    cluster/member.go:233   self ID changed from 0 to 689e371e88f78b6a
2021-06-13T09:47:14.739+08:00   INFO    cluster/member.go:154   store clusterMembers: eg-default-name(689e371e88f78b6a)=http://localhost:2380
2021-06-13T09:47:14.739+08:00   INFO    cluster/member.go:155   store knownMembers  : eg-default-name(689e371e88f78b6a)=http://localhost:2380

此时会监听默认的2379、2380、2381三个端口；

同时会在当前启动目录创建一些文件：

• data目录；
• log目录；
• member目录；
• easegress.pid文件：记录当前easegress-server的pid；

启动成功后尝试查看成员列表：

[root@localhost easegress]# egctl member list
- options:
    name: eg-default-name
    labels: {}
    cluster-name: eg-cluster-default-name
    cluster-role: writer
    cluster-request-timeout: 10s
    cluster-listen-client-urls:
    - http://localhost:2379
    cluster-listen-peer-urls:
    - http://localhost:2380
    cluster-advertise-client-urls:
    - http://localhost:2379
    cluster-initial-advertise-peer-urls:
    - http://localhost:2380
    cluster-join-urls: []
    api-addr: localhost:2381
    debug: false
    home-dir: ./
    data-dir: data
    wal-dir: ""
    log-dir: log
    member-dir: member
    cpu-profile-file: ""
    memory-profile-file: ""
  lastHeartbeatTime: "2021-06-13T12:55:21+08:00"
  etcd:
    id: 689e371e88f78b6a
    startTime: "2021-06-13T09:47:09+08:00"
    state: Leader

这是我们所启动的一个单节点集群的信息；

系统测试

创建HTTPServer

首先，我们创建一个HTTPServer来控制服务器的流量：

下面是官方提供的一个例子：

$ echo '
kind: HTTPServer
name: server-demo
port: 10080
keepAlive: true
https: false
rules:
  - paths:
    - pathPrefix: /pipeline
      backend: pipeline-demo' | egctl object create

上面的配置会创建一个名称为server-demo的HTTPServer类型的组件，该组件监听10080端口的/pipeline路由，并转发至pipeline-demo组件；

创建完成后，server端产生日志：

2021-06-13T09:48:30.195+08:00   INFO    supervisor/supervisor.go:273    create server-demo

注意到：我们还没有创建名称叫做pipeline-demo的组件，因此，此时访问127.0.0.1:10080/pipeline会报503错误；

如下：

[root@localhost easegress]# curl -v 127.0.0.1:10080/pipeline
* About to connect() to 127.0.0.1 port 10080 (#0)
*   Trying 127.0.0.1...
* Connected to 127.0.0.1 (127.0.0.1) port 10080 (#0)
> GET /pipeline HTTP/1.1
> User-Agent: curl/7.29.0
> Host: 127.0.0.1:10080
> Accept: */*
> 
< HTTP/1.1 503 Service Unavailable
< Date: Sun, 13 Jun 2021 05:08:14 GMT
< Content-Length: 0
< 
* Connection #0 to host 127.0.0.1 left intact

下面创建HTTPPipeline；

创建HTTPPipeline

HTTPPipeline是Easegress的核心部分，用于过滤、校验和转发HTTP请求！

下面我们来创建一个HTTPPipeline；

下面的例子同样由官方提供：

$ echo '
name: pipeline-demo
kind: HTTPPipeline
flow:
  - filter: proxy
filters:
  - name: proxy
    kind: Proxy
    mainPool:
      servers:
      - url: http://127.0.0.1:9095
      - url: http://127.0.0.1:9096
      - url: http://127.0.0.1:9097
      loadBalance:
        policy: roundRobin' | egctl object create

server端日志：

2021-06-13T13:14:54.667+08:00   INFO    supervisor/supervisor.go:273    create pipeline-demo

这个HTTPPipeline将使用roundRobin算法为后端的三个服务提供负载均衡：

• url: http://127.0.0.1:9095
• url: http://127.0.0.1:9096
• url: http://127.0.0.1:9097

这时我们还是不能进行测试的，因为我们还没有后端服务；

所幸官方已经提供了这么一个后端服务：

• https://github.com/megaease/easegress/blob/main/example/backend-service/mirror.go

下面我们来启动后端服务；

启动后端服务

为了让我们的测试更加明显，我对官方提供的服务做了一些修改；

修改后的后端服务的代码如下：

mirror.go

package main

import (
    "flag"
    "fmt"
    "io"
    "io/ioutil"
    "net/http"
    "time"
)

func main() {
    port := flag.Int("p", 9095, "server port, default: 9095")
    flag.Parse()

    helloHandler := func(w http.ResponseWriter, req *http.Request) {
        _, _ = io.WriteString(w, "hello")
    }
    mirrorHandler := func(w http.ResponseWriter, req *http.Request) {
        time.Sleep(10 * time.Millisecond)
        body, err := ioutil.ReadAll(req.Body)
        if err != nil {
            body = []byte(fmt.Sprintf("<read failed: %v>", err))
        }

        url := req.URL.Path
        if req.URL.Query().Encode() != "" {
            url += "?" + req.URL.Query().Encode()
        }

        content := fmt.Sprintf(`Your Request server from port %d
===============
Method: %s
URL   : %s
Header: %v
Body  : %s\n
`, *port, req.Method, url, req.Header, body)

        _, _ = io.WriteString(w, content)
    }

    http.HandleFunc("/", mirrorHandler)
    http.HandleFunc("/pipeline/activity/1", helloHandler)
    http.HandleFunc("/pipeline/activity/2", helloHandler)

    fmt.Printf("Server started at port: %d\n", *port)
    _ = http.ListenAndServe(fmt.Sprintf(":%d", *port), nil)
}

可以看到，服务默认监听了9095端口，但是我们可以通过

同时，各个路由的Handler：

• /：mirrorHandler；
• /pipeline/activity/1：helloHandler；
• /pipeline/activity/2：helloHandler；

下面启动服务：

[root@localhost easegress]# go run mirror.go &
Server started at port: 9095
[root@localhost easegress]# go run mirror.go -p 9096 &
Server started at port: 9096
[root@localhost easegress]# go run mirror.go -p 9097 &
Server started at port: 9097

# 查看后台服务
[root@localhost easegress]# jobs
[1]   Running                 go run mirror.go &
[2]-  Running                 go run mirror.go -p 9096 &
[3]+  Running                 go run mirror.go -p 9097 &

服务已经成功启动，并监听9095~9097端口；

服务测试

注意到，在之前的配置中，我们创建的HTTPServer监听的是10080端口的/pipeline路由，并将流量转发至HTTPPipeline；

而HTTPPipeline会负载均衡至http://127.0.0.1:9095~http://127.0.0.1:9097三个服务；

所以我们通过访问http://127.0.0.1:10080/pipeline进行测试！

测试如下：

[root@localhost easegress]# curl http://127.0.0.1:10080/pipeline -d 'Hello, Easegress'
Your Request server from port 9095
===============
Method: POST
URL   : /pipeline
Header: map[Accept:[*/*] Accept-Encoding:[gzip] Content-Type:[application/x-www-form-urlencoded] User-Agent:[curl/7.29.0]]
Body  : Hello, Easegress

[root@localhost easegress]# curl http://127.0.0.1:10080/pipeline -d 'Hello, Easegress'
Your Request server from port 9096
===============
Method: POST
URL   : /pipeline
Header: map[Accept:[*/*] Accept-Encoding:[gzip] Content-Type:[application/x-www-form-urlencoded] User-Agent:[curl/7.29.0]]
Body  : Hello, Easegress

[root@localhost easegress]# curl http://127.0.0.1:10080/pipeline -d 'Hello, Easegress'
Your Request server from port 9097
===============
Method: POST
URL   : /pipeline
Header: map[Accept:[*/*] Accept-Encoding:[gzip] Content-Type:[application/x-www-form-urlencoded] User-Agent:[curl/7.29.0]]
Body  : Hello, Easegress

[root@localhost easegress]# curl http://127.0.0.1:10080/pipeline -d 'Hello, Easegress'
Your Request server from port 9095
===============
Method: POST
URL   : /pipeline
Header: map[Accept:[*/*] Accept-Encoding:[gzip] Content-Type:[application/x-www-form-urlencoded] User-Agent:[curl/7.29.0]]
Body  : Hello, Easegress

可以看到，服务的确是以roundRobin算法来进行负载均衡的！

热替换Filter

上面我们定义了一个负载均衡的Filter，具体内容如下：

name: pipeline-demo
kind: HTTPPipeline
flow:
  - filter: proxy
filters:
  - name: proxy
    kind: Proxy
    mainPool:
      servers:
      - url: http://127.0.0.1:9095
      - url: http://127.0.0.1:9096
      - url: http://127.0.0.1:9097
      loadBalance:
        policy: roundRobin

下面，我们通过Easegress插件式的热替换，将现有的HTTPPipeline替换为其他类型的；

我们在原来的HTTPPipeline之上，增加参数校验和请求适配功能；

创建pipeline-demo.yaml文件：

pipeline-demo.yaml

name: pipeline-demo
kind: HTTPPipeline
flow:
  - filter: validator
    jumpIf: { invalid: END }
  - filter: requestAdaptor
  - filter: proxy
filters:
  - name: validator
    kind: Validator
    headers:
      Content-Type:
        values:
        - application/json
  - name: requestAdaptor
    kind: RequestAdaptor
    header:
      set:
        X-Adapt-Key: goodplan
  - name: proxy
    kind: Proxy
    mainPool:
      servers:
      - url: http://127.0.0.1:9095
      - url: http://127.0.0.1:9096
      - url: http://127.0.0.1:9097
      loadBalance:
        policy: roundRobin

下面介绍一下上面的配置；

首先在flow部分，定义了整个HTTPPipeline的过滤流（过滤链），同时如果在validator部分出现了invalid，则直接退出Filter；

flow部分定义的各个步骤都在下面的filters数组中定义；

在validator中，我们定义了一个Validator类型的Filter，用于校验header中包括了Content-Type:"application/json"；

在requestAdaptor中，我们定义了RequestAdaptor类型的Filter，用于在响应的Header中添加X-Adapt-Key: "goodplan"；

proxy仍然是我们之前的定义；

文件编辑后，通过egctl object update -f应用（类似于kubectl apply -f）：

egctl object update -f pipeline-demo.yaml

更新后server端日志：

2021-06-13T14:19:44.233+08:00   INFO    supervisor/supervisor.go:276    update pipeline-demo

此时再进行测试：

[root@localhost easegress]# curl -v http://127.0.0.1:10080/pipeline -d 'Hello, Easegress'
* About to connect() to 127.0.0.1 port 10080 (#0)
*   Trying 127.0.0.1...
* Connected to 127.0.0.1 (127.0.0.1) port 10080 (#0)
> POST /pipeline HTTP/1.1
> User-Agent: curl/7.29.0
> Host: 127.0.0.1:10080
> Accept: */*
> Content-Length: 16
> Content-Type: application/x-www-form-urlencoded
> 
* upload completely sent off: 16 out of 16 bytes
< HTTP/1.1 400 Bad Request
< Date: Sun, 13 Jun 2021 06:20:25 GMT
< Content-Length: 0
< 
* Connection #0 to host 127.0.0.1 left intact

可以看到Server端返回400错误！

加上Header后再次测试：

[root@localhost easegress]# curl http://127.0.0.1:10080/pipeline -H 'Content-Type: application/json' -d '{"message": "Hello, Easegress"}'
Your Request server from port 9095
===============
Method: POST
URL   : /pipeline
Header: map[Accept:[*/*] Accept-Encoding:[gzip] Content-Type:[application/json] User-Agent:[curl/7.29.0] X-Adapt-Key:[goodplan]]
Body  : {"message": "Hello, Easegress"}

可以看到，请求正常返回；

同时，返回的响应中的Header部分加入了X-Adapt-Key:[goodplan]]；

也可以通过egctl object list查看相关组件：

[root@localhost easegress]# egctl object list
- filters:
  - headers:
      Content-Type:
        values:
        - application/json
    kind: Validator
    name: validator
  - header:
      set:
        X-Adapt-Key: goodplan
    kind: RequestAdaptor
    name: requestAdaptor
  - kind: Proxy
    mainPool:
      loadBalance:
        policy: roundRobin
      servers:
      - url: http://127.0.0.1:9095
      - url: http://127.0.0.1:9096
      - url: http://127.0.0.1:9097
    name: proxy
  flow:
  - filter: validator
    jumpIf:
      invalid: END
  - filter: requestAdaptor
  - filter: proxy
  kind: HTTPPipeline
  name: pipeline-demo
- https: false
  keepAlive: true
  kind: HTTPServer
  name: server-demo
  port: 10080
  rules:
  - paths:
    - backend: pipeline-demo
      pathPrefix: /pipeline

实验成功！

此处包括了更多类型的Filter说明：

• https://github.com/megaease/easegress/blob/main/doc/filters.md

总结

从上面的实验可以看到，Easegress使用起来还是很方便的；

仅仅通过配置文件即可对请求、路由等进行设置，体验和K8S基本上类似；

当然Easegress所提供的功能还有很多很多，有兴趣的可以查看官方文档：

• https://www.megaease.com/docs/easegress/

附录

源代码：

• https://github.com/JasonkayZK/Go_Learn/tree/easegress-demo

Easegress项目地址：

• https://github.com/megaease/easegress#get-started

官方文档：

• https://www.megaease.com/docs/easegress/