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How Higress Works

发表于 分类于 ， ， 阅读次数：

在 阿里巴巴开源下一代云原生网关Higress：基于Envoy，支持Nginx Ingress零成本快速迁移中，介绍了阿里开源的云原生网关。
我们今天就来探索下，这个项目是做了什么，他又是怎么工作的。

Intro

对于一个全新的系统，我们首先从架构上切入是一个比较的好的选择。

从架构图上，我们可以发现，整体还是分成了

  • 控制面: istio + Higress Controller
  • 数据面: Higress Data Plane

从图上我们就可以猜测出，数据面 是基于 Envoy + 一些自定义的插件来构成的。而控制面 看起来并不是很直观。
从上图可以看出 istio 和 Envoy 通讯，而 higress 不直接和 Envoy 通讯，因此，我们可以大胆的猜测 Higress 作为 istio 的 MCP 远端数据源提供服务给 istio。那么基于这的假设我们来看看它是如何工作的。

How it works

初始化环境

直接看代码是不明智的，一般来说我们先从一个项目的 Statup 开始，对一个项目有自己的观感才是比较好的选择。那我们先按照社区的文档初始化这个项目

  1. 安装 istio
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kubectl create ns istio-system
helm install istio -n istio-system oci://higress-registry.cn-hangzhou.cr.aliyuncs.com/charts/istio

需要 helm 较高版本的，如果运行出现 failed to download “oci://higress-registry.cn-hangzhou.cr.aliyuncs.com/charts/istio” (hint: running helm repo update may help)，更新helm即可。

  1. 安装 higess
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kubectl create ns higress-system
helm install higress -n higress-system oci://higress-registry.cn-hangzhou.cr.aliyuncs.com/charts/higress
  1. 创建 Ingress 配置

假设在 default 命名空间下已经部署了一个 demo service，服务端口为 80 ，则创建下面这个 K8s Ingress

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apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: simple-example
spec:
  rules:
  - host: demo.bar.com
    http:
      paths:
      - path: /demo
        pathType: Prefix
        backend:
          service:
            name: demo
            port:
              number: 80

最终环境

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$ kubectl get pod -A
NAMESPACE        NAME                                 READY   STATUS    RESTARTS   AGE
default          echo-web-89668cbcc-7jsx7             1/1     Running   0          82s
default          echo-web-89668cbcc-zxjsl             1/1     Running   0          82s
higress-system   higress-controller-857bc7484-znslv   1/1     Running   0          2m54s
higress-system   higress-gateway-74cb5978cc-fw28r     1/1     Running   0          2m54s
istio-system     istiod-5bf74cd79b-9gzm9              1/1     Running   0          6m59s
  1. 执行访问
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$ curl "$(k get svc -n higress-system higress-gateway -o jsonpath='{.status.loadBalancer.ingress[0].ip}')"/demo -H 'host: demo.bar.com'
{"host":{"hostname":"demo.bar.com","ip":"::ffff:172.30.52.234","ips":[]},"http":{"method":"GET","baseUrl":"","originalUrl":"/demo","protocol":"http"},"request":{"params":{"0":"/demo"},"query":{},"cookies":{},"body":{},"headers":{"host":"demo.bar.com","user-agent":"curl/7.79.1","accept":"*/*","DETAILS_SERVICE_PORT":"9080","HELLOWORLD_SERVICE_PORT_HTTP":"5000","KUBERNETES_PORT_443_TCP_PORT":"443","KUBERNETES_PORT_443_TCP":"tcp://172.31.160.1:443","HOME":"/root"}}

从日志验证

首先第一步，我们可以从启动日志中去看出一些端倪，这是一个比较好的习惯。

从 istiod 日志中我们就可以获得如同我们猜想的日志信息。

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$ kubectl logs -n istio-system istiod-5bf74cd79b-9gzm9

nc: getaddrinfo for host "higress-controller.higress-system" port 15051: Name or service not known
testing higress controller is ready to connect...
nc: getaddrinfo for host "higress-controller.higress-system" port 15051: Name or service not known
testing higress controller is ready to connect...
nc: getaddrinfo for host "higress-controller.higress-system" port 15051: Name or service not known
testing higress controller is ready to connect...
2022-11-07T02:22:11.924444Z	info	FLAG: --caCertFile=""
2022-11-07T02:22:11.924484Z	info	FLAG: --clusterAliases="[]"
2022-11-07T02:22:11.938185Z	info	klog	Config not found: /var/run/secrets/remote/config
2022-11-07T02:22:11.939130Z	info	initializing mesh configuration ./etc/istio/config/mesh
2022-11-07T02:22:11.939963Z	warn	Using local mesh config file ./etc/istio/config/mesh, in cluster configs ignored
2022-11-07T02:22:11.940311Z	info	mesh configuration: {
    "proxyListenPort": 15001,
    "connectTimeout": "10s",
    "protocolDetectionTimeout": "0.100s",
    "ingressClass": "istio",
    "ingressService": "istio-ingressgateway",
    "ingressControllerMode": "STRICT",
    "enableTracing": true,
    "accessLogFile": "/dev/stdout",
    "accessLogFormat": "{\"authority\":\"%REQ(:AUTHORITY)%\",\"bytes_received\":\"%BYTES_RECEIVED%\",\"bytes_sent\":\"%BYTES_SENT%\",\"downstream_local_address\":\"%DOWNSTREAM_LOCAL_ADDRESS%\",\"downstream_remote_address\":\"%DOWNSTREAM_REMOTE_ADDRESS%\",\"duration\":\"%DURATION%\",\"istio_policy_status\":\"%DYNAMIC_METADATA(istio.mixer:status)%\",\"method\":\"%REQ(:METHOD)%\",\"path\":\"%REQ(X-ENVOY-ORIGINAL-PATH?:PATH)%\",\"protocol\":\"%PROTOCOL%\",\"request_id\":\"%REQ(X-REQUEST-ID)%\",\"requested_server_name\":\"%REQUESTED_SERVER_NAME%\",\"response_code\":\"%RESPONSE_CODE%\",\"response_flags\":\"%RESPONSE_FLAGS%\",\"route_name\":\"%ROUTE_NAME%\",\"start_time\":\"%START_TIME%\",\"trace_id\":\"%REQ(X-B3-TRACEID)%\",\"upstream_cluster\":\"%UPSTREAM_CLUSTER%\",\"upstream_host\":\"%UPSTREAM_HOST%\",\"upstream_local_address\":\"%UPSTREAM_LOCAL_ADDRESS%\",\"upstream_service_time\":\"%RESP(X-ENVOY-UPSTREAM-SERVICE-TIME)%\",\"upstream_transport_failure_reason\":\"%UPSTREAM_TRANSPORT_FAILURE_REASON%\",\"user_agent\":\"%REQ(USER-AGENT)%\",\"x_forwarded_for\":\"%REQ(X-FORWARDED-FOR)%\"}\n",
    "defaultConfig": {
        "configPath": "./etc/istio/proxy",
        "binaryPath": "/usr/local/bin/envoy",
        "serviceCluster": "istio-proxy",
        "drainDuration": "45s",
        "parentShutdownDuration": "60s",
        "discoveryAddress": "istiod.istio-system.svc:15012",
        "proxyAdminPort": 15000,
        "controlPlaneAuthPolicy": "MUTUAL_TLS",
        "statNameLength": 189,
        "concurrency": 2,
        "tracing": {
            "zipkin": {
                "address": "zipkin.istio-system:9411"
            }
        },
        "statusPort": 15020,
        "terminationDrainDuration": "5s",
        "proxyStatsMatcher": {
            "inclusionRegexps": [
                ".*"
            ]
        }
    },
    "outboundTrafficPolicy": {
        "mode": "ALLOW_ANY"
    },
    "configSources": [
        {
            "address": "k8s://"
        },
        {
            "address": "xds://higress-controller.higress-system:15051"
        }
    ],
    "enableAutoMtls": false,
    "trustDomain": "cluster.local",
    "trustDomainAliases": [
    ],
    "defaultServiceExportTo": [
        "*"
    ],
    "defaultVirtualServiceExportTo": [
        "*"
    ],
    "defaultDestinationRuleExportTo": [
        "*"
    ],
    "rootNamespace": "istio-system",
    "localityLbSetting": {
        "enabled": true
}
2022-11-07T02:22:11.940338Z	info	version: 1.12-dev-e9de7ac36deb19dcc4738a397ef3dc03579aa336-Modified
2022-11-07T02:22:11.993517Z	info	Adding Kubernetes registry adapter
2022-11-07T02:22:11.993539Z	info	handling remote clusters in *controller.Multicluster
2022-11-07T02:22:11.993557Z	info	initializing Istiod DNS certificates host: istiod.istio-system.svc, custom host:
2022-11-07T02:22:11.993606Z	info	adsc	Received higress-controller.higress-system:15051 type core/v1alpha1/MeshConfig cnt=0 nonce=51897ff3-8583-4965-ada3-0c58b6e63867
2022-11-07T02:22:11.993672Z	info	adsc	Received higress-controller.higress-system:15051 type extensions.istio.io/v1alpha1/WasmPlugin cnt=0 nonce=807490a6-10ec-4977-b21b-3ceca4eda34c
2022-11-07T02:22:11.993703Z	info	adsc	Received higress-controller.higress-system:15051 type networking.istio.io/v1alpha3/DestinationRule cnt=0 nonce=ab806b12-17e7-42da-9ab2-46ce16fdb362
2022-11-07T02:22:11.993718Z	info	adsc	Received higress-controller.higress-system:15051 type networking.istio.io/v1alpha3/EnvoyFilter cnt=0 nonce=c7ff2b1d-5a33-4c2e-aeac-d37cb1f4a1ec
2022-11-07T02:22:11.993731Z	info	adsc	Received higress-controller.higress-system:15051 type networking.istio.io/v1alpha3/Gateway cnt=0 nonce=f485bfb3-4bd9-4ff0-b069-99cdcd3849d0
2022-11-07T02:22:11.993744Z	info	adsc	Received higress-controller.higress-system:15051 type networking.istio.io/v1alpha3/ServiceEntry cnt=0 nonce=be689b82-6def-4979-9d40-538821e24328
2022-11-07T02:22:11.993760Z	info	adsc	Received higress-controller.higress-system:15051 type networking.istio.io/v1alpha3/ServiceSubscriptionList cnt=0 nonce=49ec0b57-a6e1-46ab-9ee0-99e5dfd1c758
2022-11-07T02:22:11.993773Z	info	adsc	Received higress-controller.higress-system:15051 type networking.istio.io/v1alpha3/Sidecar cnt=0 nonce=5756d43f-c8e5-44aa-bf55-38dd54911646
2022-11-07T02:22:11.993785Z	info	adsc	Received higress-controller.higress-system:15051 type networking.istio.io/v1alpha3/VirtualService cnt=0 nonce=ba88c77d-d062-4d5e-a61c-e2c98f5a4068
2022-11-07T02:22:11.993806Z	info	adsc	Received higress-controller.higress-system:15051 type networking.istio.io/v1alpha3/WorkloadEntry cnt=0 nonce=e6453814-dfff-474f-bf8d-85b190764a36
2022-11-07T02:22:11.993824Z	info	adsc	Received higress-controller.higress-system:15051 type networking.istio.io/v1alpha3/WorkloadGroup cnt=0 nonce=c8b12853-306d-443d-89de-141a02c6f525
2022-11-07T02:22:11.993840Z	info	adsc	Received higress-controller.higress-system:15051 type security.istio.io/v1beta1/AuthorizationPolicy cnt=0 nonce=b7de10db-dc94-4b15-8e02-e79173664372
2022-11-07T02:22:11.993861Z	info	adsc	Received higress-controller.higress-system:15051 type security.istio.io/v1beta1/PeerAuthentication cnt=0 nonce=273eca9d-b148-4b85-bf09-3b2bd7585353
2022-11-07T02:22:11.993879Z	info	adsc	Received higress-controller.higress-system:15051 type security.istio.io/v1beta1/RequestAuthentication cnt=0 nonce=d8b6b803-58f3-4467-a176-db911ab829f8
2022-11-07T02:22:11.993908Z	info	adsc	Received higress-controller.higress-system:15051 type telemetry.istio.io/v1alpha1/Telemetry cnt=0 nonce=5d222fc3-f44a-4a5a-a8d8-38464ec9da90

从日志中，我们就可以比较明确的得到我们之前的判断了。

  1. getaddrinfo for host "higress-controller.higress-system" port 15051: Name or service not known testing higress controller is ready to connect... 在启动之前会等待 higress-controller 的启动（应该是魔改版的 istio chart)
  2. 在配置源中多了一个上游的 MCP XDS 服务
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{
    "address": "xds://higress-controller.higress-system:15051"
}
  1. higress 会向服务器推送 istio 的配置项
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2022-11-07T02:22:11.993861Z	info	adsc	Received higress-controller.higress-system:15051 type security.istio.io/v1beta1/PeerAuthentication cnt=0 nonce=273eca9d-b148-4b85-bf09-3b2bd7585353
2022-11-07T02:22:11.993879Z	info	adsc	Received higress-controller.higress-system:15051 type security.istio.io/v1beta1/RequestAuthentication cnt=0 nonce=d8b6b803-58f3-4467-a176-db911ab829f8
2022-11-07T02:22:11.993908Z	info	adsc	Received higress-controller.higress-system:15051 type telemetry.istio.io/v1alpha1/Telemetry cnt=0 nonce=5d222fc3-f44a-4a5a-a8d8-38464ec9da90

从配置项认证

当我们已经有了明确的认知的时候，我们再来看 Envoy 的配置项

首先生成了一个 80 的 Listener

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{
    "name": "0.0.0.0_80",
    "active_state": {
    "version_info": "2022-11-07T02:41:43Z/8",
    "listener": {
        "@type": "type.googleapis.com/envoy.config.listener.v3.Listener",
        "name": "0.0.0.0_80",
        "address": {
        "socket_address": {
            "address": "0.0.0.0",
            "port_value": 80
        }
        },
        "filter_chains": [
        {
            "filters": [
            {
                "name": "envoy.filters.network.http_connection_manager",
                "typed_config": {
                "@type": "type.googleapis.com/envoy.extensions.filters.network.http_connection_manager.v3.HttpConnectionManager",
                "stat_prefix": "outbound_0.0.0.0_80",
                "rds": {
                    "config_source": {
                    "ads": {
                        
                    },
                    "initial_fetch_timeout": "0s",
                    "resource_api_version": "V3"
                    },
                    "route_config_name": "http.80"
                },

然后生成了 Router

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{
    "version_info": "2022-11-07T02:41:43Z/9",
    "route_config": {
    "@type": "type.googleapis.com/envoy.config.route.v3.RouteConfiguration",
    "name": "http.80",
    "virtual_hosts": [
        {
        "name": "demo.bar.com:80",
        "domains": [
            "demo.bar.com",
            "demo.bar.com:*"
        ],
        "routes": [
            {
            "match": {
                "case_sensitive": true,
                "safe_regex": {
                "google_re2": {
                    
                },
                "regex": "/demo((\\/).*)?"
                }
            },
            "route": {
                "cluster": "outbound|80||echo-web.default.svc.cluster.local",
                "timeout": "0s",
                "retry_policy": {
                "retry_on": "connect-failure,refused-stream,unavailable,cancelled,retriable-status-codes",
                "num_retries": 2,
                "retry_host_predicate": [
                    {
                    "name": "envoy.retry_host_predicates.previous_hosts"
                    }
                ],
                "host_selection_retry_max_attempts": "5",
                "retriable_status_codes": [
                    503
                ],
                "retriable_request_headers": [
                    {
                    "name": ":method",
                    "invert_match": true,
                    "string_match": {
                        "safe_regex": {
                        "google_re2": {
                            
                        },
                        "regex": "POST|PATCH|LOCK"
                        }
                    }
                    }
                ]
                },
                "max_grpc_timeout": "0s"
            },
            "metadata": {
                "filter_metadata": {
                "istio": {
                    "config": "/apis/networking.istio.io/v1alpha3/namespaces/higress-system/virtual-service/default-simple-example-demo-bar-com"
                }
                }
            },
            "decorator": {
                "operation": "echo-web.default.svc.cluster.local:80/demo((\\/).*)?"
            },
            "name": "default-simple-example-34da3948"
            },
    ],
    "validate_clusters": false
    },

这么看起来也挺明显的。并且因为 Higress Gateway 连接的地址是 istiod

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$ kubectl logs -n higress-system higress-gateway-74cb5978cc-2sv8k

defaultConfig:
  discoveryAddress: istiod.istio-system.svc:15012

那和我们猜测的架构一致。

阅读代码

最后我们来看看代码里面，做了些什么，从项目的结构上，我们就知道他分为 数据面和 控制面，数据面对 Envoy 做了一些扩展，这部分都在 extensions 中。这部分的逻辑就不做展开了。

重点还是看看控制面的逻辑。这部分的代码都在 ingress 之中。

控制面启动 XDS

对于任何的 Operator 组件来说，我们第一步需要关心的是它关注什么资源的变化，这里在下面的代码中，我们可以看出来，Ingress Controller 关注下面的几个配置类型。

initRegistryEventHandlersgithub
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var IngressIR = collection.NewSchemasBuilder().
	MustAdd(collections.IstioExtensionsV1Alpha1Wasmplugins).
	MustAdd(collections.IstioNetworkingV1Alpha3Destinationrules).
	MustAdd(collections.IstioNetworkingV1Alpha3Envoyfilters).
	MustAdd(collections.IstioNetworkingV1Alpha3Gateways).
	MustAdd(collections.IstioNetworkingV1Alpha3Serviceentries).
	MustAdd(collections.IstioNetworkingV1Alpha3Virtualservices).
	Build()

// initRegistryEventHandlers sets up event handlers for config updates
func (s *Server) initRegistryEventHandlers() error {
	log.Info("initializing registry event handlers")
	configHandler := func(prev config.Config, curr config.Config, event model.Event) {
		// For update events, trigger push only if spec has changed.
		pushReq := &model.PushRequest{
			Full: true,
			ConfigsUpdated: map[model.ConfigKey]struct{}{{
				Kind:      curr.GroupVersionKind,
				Name:      curr.Name,
				Namespace: curr.Namespace,
			}: {}},
			Reason: []model.TriggerReason{model.ConfigUpdate},
		}
		s.xdsServer.ConfigUpdate(pushReq)
	}
	schemas := IngressIR.All()
	for _, schema := range schemas {
		s.configController.RegisterEventHandler(schema.Resource().GroupVersionKind(), configHandler)
	}
	return nil
}

对于这些资源的处理在

RegisterEventHandlergithub
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func (m *IngressConfig) RegisterEventHandler(kind config.GroupVersionKind, f model.EventHandler) {
	IngressLog.Infof("register resource %v", kind)
	if kind != gvk.VirtualService && kind != gvk.Gateway &&
		kind != gvk.DestinationRule && kind != gvk.EnvoyFilter {
		return
	}

	switch kind {
	case gvk.VirtualService:
		m.virtualServiceHandlers = append(m.virtualServiceHandlers, f)

	case gvk.Gateway:
		m.gatewayHandlers = append(m.gatewayHandlers, f)

	case gvk.DestinationRule:
		m.destinationRuleHandlers = append(m.destinationRuleHandlers, f)

	case gvk.EnvoyFilter:
		m.envoyFilterHandlers = append(m.envoyFilterHandlers, f)
	}

	for _, remoteIngressController := range m.remoteIngressControllers {
		remoteIngressController.RegisterEventHandler(kind, f)
	}
}

而执行逻辑就是把这个 handlers 挨个执行一遍

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for _, f := range c.gatewayHandlers {
    f(config.Config{Meta: gatewaymetadata}, config.Config{Meta: gatewaymetadata}, event)
}

实际上，也只是通知下 istiod，Push 一个事件给 istiod，等 istiod 来拉取。

这是这个 Xds 的逻辑，我们来看看 higress 到底做了什么。

Controller

在 Controller 的 onEvent 事件中，我们发现也就是关注了 Ingress 这个 CR 资源，然后把所有的 Handlers 执行了一遍。

onEventgithub
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func (c *controller) onEvent(namespacedName types.NamespacedName) error {
	event := model.EventUpdate
	ing, err := c.ingressLister.Ingresses(namespacedName.Namespace).Get(namespacedName.Name)
	if err != nil {
		if kerrors.IsNotFound(err) {
			event = model.EventDelete
			c.mutex.Lock()
			ing = c.ingresses[namespacedName.String()]
			delete(c.ingresses, namespacedName.String())
			c.mutex.Unlock()
		} else {
			return err
		}
	}

	// ingress deleted, and it is not processed before
	if ing == nil {
		return nil
	}

	// we should check need process only when event is not delete,
	// if it is delete event, and previously processed, we need to process too.
	if event != model.EventDelete {
		shouldProcess, err := c.shouldProcessIngressUpdate(ing)
		if err != nil {
			return err
		}
		if !shouldProcess {
			IngressLog.Infof("no need process, ingress %s", namespacedName)
			return nil
		}
	}

	drmetadata := config.Meta{
		Name:             ing.Name + "-" + "destinationrule",
		Namespace:        ing.Namespace,
		GroupVersionKind: gvk.DestinationRule,
		// Set this label so that we do not compare configs and just push.
		Labels: map[string]string{constants.AlwaysPushLabel: "true"},
	}
	vsmetadata := config.Meta{
		Name:             ing.Name + "-" + "virtualservice",
		Namespace:        ing.Namespace,
		GroupVersionKind: gvk.VirtualService,
		// Set this label so that we do not compare configs and just push.
		Labels: map[string]string{constants.AlwaysPushLabel: "true"},
	}
	efmetadata := config.Meta{
		Name:             ing.Name + "-" + "envoyfilter",
		Namespace:        ing.Namespace,
		GroupVersionKind: gvk.EnvoyFilter,
		// Set this label so that we do not compare configs and just push.
		Labels: map[string]string{constants.AlwaysPushLabel: "true"},
	}
	gatewaymetadata := config.Meta{
		Name:             ing.Name + "-" + "gateway",
		Namespace:        ing.Namespace,
		GroupVersionKind: gvk.Gateway,
		// Set this label so that we do not compare configs and just push.
		Labels: map[string]string{constants.AlwaysPushLabel: "true"},
	}

	for _, f := range c.destinationRuleHandlers {
		f(config.Config{Meta: drmetadata}, config.Config{Meta: drmetadata}, event)
	}

	for _, f := range c.virtualServiceHandlers {
		f(config.Config{Meta: vsmetadata}, config.Config{Meta: vsmetadata}, event)
	}

	for _, f := range c.envoyFilterHandlers {
		f(config.Config{Meta: efmetadata}, config.Config{Meta: efmetadata}, event)
	}

	for _, f := range c.gatewayHandlers {
		f(config.Config{Meta: gatewaymetadata}, config.Config{Meta: gatewaymetadata}, event)
	}

	return nil
}

当前的大部分代码逻辑都在 annotations 里面，也就是当前支持的各个功能

NewAnnotationHandlerManagergithub
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func NewAnnotationHandlerManager() AnnotationHandler {
	return &AnnotationHandlerManager{
		parsers: []Parser{
			canary{},
			cors{},
			downstreamTLS{},
			redirect{},
			rewrite{},
			upstreamTLS{},
			ipAccessControl{},
			headerControl{},
			timeout{},
			retry{},
			loadBalance{},
			localRateLimit{},
			fallback{},
			auth{},
		},
		gatewayHandlers: []GatewayHandler{
			downstreamTLS{},
		},
		virtualServiceHandlers: []VirtualServiceHandler{
			ipAccessControl{},
		},
		routeHandlers: []RouteHandler{
			cors{},
			redirect{},
			rewrite{},
			ipAccessControl{},
			headerControl{},
			timeout{},
			retry{},
			localRateLimit{},
			fallback{},
		},
		trafficPolicyHandlers: []TrafficPolicyHandler{
			upstreamTLS{},
			loadBalance{},
		},
	}
}

这里以 cors 为例子。

Parsegithub
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func (c cors) Parse(annotations Annotations, config *Ingress, _ *GlobalContext) error {
    // 判断了anontations 中是否需要配置 cors
	if !needCorsConfig(annotations) {
		return nil
	}

	// cors enable
	enable, _ := annotations.ParseBoolASAP(enableCors)
	if !enable {
		return nil
	}
    
    // 生成一个 CORS 的配置
	corsConfig := &CorsConfig{
		Enabled:          enable,
		AllowOrigin:      []string{defaultAllowOrigin},
		AllowMethods:     splitStringWithSpaceTrim(defaultAllowMethods),
		AllowHeaders:     splitStringWithSpaceTrim(defaultAllowHeaders),
		AllowCredentials: defaultAllowCredentials,
		MaxAge:           defaultMaxAge,
	}
    
    // 最终 Append 到配置中去，再下面就是各种配置
	defer func() {
		config.Cors = corsConfig
	}()

	// allow origin
	if origin, err := annotations.ParseStringASAP(allowOrigin); err == nil {
		corsConfig.AllowOrigin = splitStringWithSpaceTrim(origin)
	}

	// allow methods
	if methods, err := annotations.ParseStringASAP(allowMethods); err == nil {
		corsConfig.AllowMethods = splitStringWithSpaceTrim(methods)
	}

	// allow headers
	if headers, err := annotations.ParseStringASAP(allowHeaders); err == nil {
		corsConfig.AllowHeaders = splitStringWithSpaceTrim(headers)
	}

	// expose headers
	if exposeHeaders, err := annotations.ParseStringASAP(exposeHeaders); err == nil {
		corsConfig.ExposeHeaders = splitStringWithSpaceTrim(exposeHeaders)
	}

	// allow credentials
	if allowCredentials, err := annotations.ParseBoolASAP(allowCredentials); err == nil {
		corsConfig.AllowCredentials = allowCredentials
	}

	// max age
	if age, err := annotations.ParseIntASAP(maxAge); err == nil {
		corsConfig.MaxAge = age
	}

	return nil
}

处理逻辑衔接

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func (m *IngressConfig) List(typ config.GroupVersionKind, namespace string) ([]config.Config, error) {
	if typ != gvk.Gateway &&
		typ != gvk.VirtualService &&
		typ != gvk.DestinationRule &&
		typ != gvk.EnvoyFilter {
		return nil, common.ErrUnsupportedOp
	}

	// Currently, only support list all namespaces gateways or virtualservices.
	if namespace != "" {
		IngressLog.Warnf("ingress store only support type %s of all namespace.", typ)
		return nil, common.ErrUnsupportedOp
	}

	if typ == gvk.EnvoyFilter {
		m.mutex.RLock()
		defer m.mutex.RUnlock()
		IngressLog.Infof("resource type %s, configs number %d", typ, len(m.cachedEnvoyFilters))
		return m.cachedEnvoyFilters, nil
	}

	var configs []config.Config
	m.mutex.RLock()
	for _, ingressController := range m.remoteIngressControllers {
		configs = append(configs, ingressController.List()...)
	}
	m.mutex.RUnlock()

	common.SortIngressByCreationTime(configs)
	wrapperConfigs := m.createWrapperConfigs(configs)

    // 根据 istiod 的 List 请求的内容就返回对应的数据
	IngressLog.Infof("resource type %s, configs number %d", typ, len(wrapperConfigs))
	switch typ {
	case gvk.Gateway:
		return m.convertGateways(wrapperConfigs), nil
	case gvk.VirtualService:
		return m.convertVirtualService(wrapperConfigs), nil
	case gvk.DestinationRule:
		return m.convertDestinationRule(wrapperConfigs), nil
	}

	return nil, nil
}

到这里其实我们把整个流程梳理下

到这里我们发现其实整个 Higress 的逻辑当前还是比较的简单的，就是处理一些 annotations 中的信息，转为 istio 的数据。

开发环境搭建

社区Readme 少了这部分，也就是初始化 submodules

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make prebuild

即可。

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来杯奶茶, 嗝~~~