前置条件
k8s集群，版本1.23.8
安装方法略
istio安装完成demo，版本1.17.2
curl -L https://git.io/getLatestIstio | ISTIO_VERSION=1.17.2 sh
cd istio-1.17.2/
./bin/istioctl install --set profile=demo -y
kubectl label namespace default istio-injection=enabled --overwrite
安装httpbin，sleep 示例
httpbin主要为了提供http响应，也可以用已有的能够提供http服务的任意服务。
sleep 为了在pod里使用curl命令，有别的pod中能执行curl命令也可以。
kubectl apply -f samples/httpbin/httpbin.yaml
kubectl apply -f samples/sleep/sleep.yaml
本地docker环境，版本 20.10.21
docker安装略
go语言环境，版本1.18.1
go安装略
阿里云或其他镜像仓库
类似部署一个普通应用，wasm插件来源于某个镜像仓库。
为了方便使用了阿里云的免费镜像仓库，也可以本地搭建或使用别的仓库。
注意需要将阿里云的仓库设置为公开！
示例功能
-
在请求头增加自定义的返回信息
-
将插件的配置信息放到头信息中返回（测试读取配置的功能）
-
简单的限流功能
直接看效果
使用我编译好的镜像直接部署，保存以下内容为 gowasm.yaml
apiVersion: extensions.istio.io/v1alpha1
kind: WasmPlugin
metadata:
name: my-go-wasm-plugin
namespace: default
spec:
selector:
matchLabels:
app: httpbin
## 编译好的镜像
url: oci://registry.cn-hangzhou.aliyuncs.com/hallywang/gowasm:20230530181612
#插件的配置信息，在代码中可以获取到json string
pluginConfig:
testConfig: abcddeeeee
listconfig:
- abc
- def
部署到k8s中
kubectl apply -f gowasm.yaml
示例验证方法
- 执行以下命令，从sleep pod中发送http 请求到 httpbin ，打印出返回的header
SLEEP_POD=$(kubectl get pod -l app=sleep -o jsonpath={.items..metadata.name}
kubectl exec ${SLEEP_POD} -c sleep -- sh -c 'for i in $(seq 1 3); do curl --head -s httpbin:8000/headers; sleep 0.1; done'
-
在未部署gowasm.yaml之前，每次请求都会返回200成功，且头信息中没有自定义的内容
-
在部署了gowasm.yaml之后，返回如下结果（两次请求的结果），有自定义的头信息和403的返回说明插件部署成功。
## 第一次请求的返回结果： HTTP/1.1 200 OK server: envoy date: Wed, 31 May 2023 03:20:12 GMT content-type: application/json content-length: 526 access-control-allow-origin: * access-control-allow-credentials: true x-envoy-upstream-service-time: 3 ## 下面是插件增加的头信息 who-am-i: wasm-extension injected-by: istio-api! hally: wang wang: 1234567 configdata: {"listconfig":["abc","def"],"testConfig":"abcddeeeee"} ## 第二次请求的返回结果： ## 限流起作用，返回403 HTTP/1.1 403 Forbidden powered-by: proxy-wasm-go-sdk!! content-length: 29 content-type: text/plain who-am-i: wasm-extension injected-by: istio-api! hally: wang wang: 1234567 configdata: {"listconfig":["abc","def"],"testConfig":"abcddeeeee"} date: Wed, 31 May 2023 03:20:12 GMT server: envoy x-envoy-upstream-service-time: 0
从代码开始
安装tinygo
tinygo可以将go编译成wasm文件
https://tinygo.org/getting-started/install/
创建go工程
mkdir go-wasm-plugin
cd go-wasm-plugin
go mod init go-wasm
新增文件main.go
package main
import (
"time"
"github.com/tetratelabs/proxy-wasm-go-sdk/proxywasm"
"github.com/tetratelabs/proxy-wasm-go-sdk/proxywasm/types"
)
func main() {
proxywasm.SetVMContext(&vmContext{})
}
type vmContext struct {
// Embed the default VM context here,
// so that we don't need to reimplement all the methods.
types.DefaultVMContext
}
// Override types.DefaultVMContext.
func (*vmContext) NewPluginContext(contextID uint32) types.PluginContext {
return &pluginContext{}
}
type pluginContext struct {
// Embed the default plugin context here,
// so that we don't need to reimplement all the methods.
types.DefaultPluginContext
// the remaining token for rate limiting, refreshed periodically.
remainToken int
// // the preconfigured request per second for rate limiting.
// requestPerSecond int
// NOTE(jianfeih): any concerns about the threading and mutex usage for tinygo wasm?
// the last time the token is refilled with `requestPerSecond`.
lastRefillNanoSec int64
}
// Override types.DefaultPluginContext.
func (p *pluginContext) NewHttpContext(contextID uint32) types.HttpContext {
return &httpHeaders{contextID: contextID, pluginContext: p}
}
type httpHeaders struct {
// Embed the default http context here,
// so that we don't need to reimplement all the methods.
types.DefaultHttpContext
contextID uint32
pluginContext *pluginContext
}
// Additional headers supposed to be injected to response headers.
var additionalHeaders = map[string]string{
"who-am-i": "go-wasm-extension",
"injected-by": "istio-api!",
"hally": "wang",
"wang": "1234567",
// 定义自定义的header，每个返回中都添加以上header
}
// 读取部署yaml中的 pluginConfig 内容，用于插件的一些配置信息
var configData string
func (p *pluginContext) OnPluginStart(pluginConfigurationSize int) types.OnPluginStartStatus {
proxywasm.LogDebug("loading plugin config")
data, err := proxywasm.GetPluginConfiguration()
if data == nil {
return types.OnPluginStartStatusOK
}
if err != nil {
proxywasm.LogCriticalf("error reading plugin configuration: %v", err)
return types.OnPluginStartStatusFailed
}
// 插件启动的时候读取配置
configData = string(data)
return types.OnPluginStartStatusOK
}
func (ctx *httpHeaders) OnHttpResponseHeaders(numHeaders int, endOfStream bool) types.Action {
//添加headr
for key, value := range additionalHeaders {
proxywasm.AddHttpResponseHeader(key, value)
}
//为了便于演示观察，将配置信息也加到返回头里
proxywasm.AddHttpResponseHeader("configData", configData)
return types.ActionContinue
}
// 实现限流
func (ctx *httpHeaders) OnHttpRequestHeaders(int, bool) types.Action {
current := time.Now().UnixNano()
// We use nanoseconds() rather than time.Second() because the proxy-wasm has the known limitation.
// TODO(incfly): change to time.Second() once https://github.com/proxy-wasm/proxy-wasm-cpp-host/issues/199
// is resolved and released.
if current > ctx.pluginContext.lastRefillNanoSec+1e9 {
ctx.pluginContext.remainToken = 2
ctx.pluginContext.lastRefillNanoSec = current
}
proxywasm.LogCriticalf("Current time %v, last refill time %v, the remain token %v",
current, ctx.pluginContext.lastRefillNanoSec, ctx.pluginContext.remainToken)
if ctx.pluginContext.remainToken == 0 {
if err := proxywasm.SendHttpResponse(403, [][2]string{
{"powered-by", "proxy-wasm-go-sdk!!"},
}, []byte("rate limited, wait and retry."), -1); err != nil {
proxywasm.LogErrorf("failed to send local response: %v", err)
proxywasm.ResumeHttpRequest()
}
return types.ActionPause
}
ctx.pluginContext.remainToken -= 1
return types.ActionContinue
}
新增文件 Dockerfile
# Dockerfile for building "compat" variant of Wasm Image Specification.
# https://github.com/solo-io/wasm/blob/master/spec/spec-compat.md
FROM scratch
COPY main.wasm ./plugin.wasm
编译go代码为wasm
go get
tinygo build -o main.wasm -scheduler=none -target=wasi main.go
编译成功后，工程目录中将出现 main.wasm 文件
build一个Docker镜像,推送到镜像仓库
docker build . -t registy.cn-hangzhou.aliyuncs.com/USER_NAME/gowasm:0.1
docker push registy.cn-hangzhou.aliyuncs.com/USER_NAME/gowasm:0.1
新增部署yaml
gowasm.yaml
apiVersion: extensions.istio.io/v1alpha1
kind: WasmPlugin
metadata:
name: my-go-wasm-plugin
namespace: default
spec:
selector:
matchLabels:
app: httpbin
url: oci://registry.cn-hangzhou.aliyuncs.com/USER_NAME/gowasm:0.1
pluginConfig:
testConfig: abcddeeeee
listconfig:
- abc
- def
部署到k8s,执行测试脚本
kubectl apply -f gowasm.yaml
SLEEP_POD=$(kubectl get pod -l app=sleep -o jsonpath={.items..metadata.name}
kubectl exec ${SLEEP_POD} -c sleep -- sh -c 'for i in $(seq 1 3); do curl --head -s httpbin:8000/headers; sleep 0.1; done'
## 观察返回内容
删除插件
kubectl delete wasmplugins my-go-wasm-plugin
遇到的问题
- 修改代码重新发布部署后，如果镜像的tag没变化，可能出现不生效，这是因为wasmplugin有自己的缓存机制,tag版本发生变化，不会出现该问题
本文代码
https://github.com/hallywang/go-wasm-plugin-example.git
其他玩法
- istio官方提供的使用webassemblyhub来打包发布，内容参考
https://istio.io/latest/zh/blog/2020/deploy-wasm-declarative/
但是发现webassemblyhub提供的工具不支持最新版本的istio。
参考资料
https://tetrate.io/blog/istio-wasm-extensions-and-ecosystem/
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