title: 流量编排系统Easegress初探 toc: true cover: 'https://img.paulzzh.com/touhou/random?123' date: 2021-06-13 10:06:46 categories: Golang tags: [Golang, Easegress]
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：
<br/>
<!--more-->Easegress的安装可以说是相当简单了；
其实就是两个二进制文件：
可以直接通过下载仓库的Release安装：
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；
<br/>
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：
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；
<br/>
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
<font color="#ff0000">**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；**</font>
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；
<br/>
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：
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：
下面我们来启动后端服务；
<br/>
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；
<br/>
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！
<br/>
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：
<br/>
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：
<br/>
源代码：
Easegress项目地址：
官方文档：
<br/>