Istio traffic management -- progress gateway

Traditionally ,Kubernetes Use Ingress Controller to handle traffic from outside into the cluster . Use Istio when , This is no longer the case . Istio Have used new Gateway and VirtualServices Resources replace the familiar Ingress resources . They work together , Route traffic to the grid . Inside the grid , Unwanted Gateway, Because services can access each other through cluster local service names .

As I mentioned in my previous article ,kubernetes Provided Ingress Too simple , The exposed attributes are too weak to express . Of course, the community is aware of the problem , from kubernetes1.19 edition , Gradually complete the function .Istio In solution , Did it on its own Istio gateway. In Africa istio Out of the scene ,gloo,ambasaador ,contour Equal gateway It can meet the needs of our production environment .

Deploy

Let's take a look at the community's default deployment .

adopt Deployment A group of managers istio-ingressgateway Pod.

IngressGateway, This is a Envoy Encapsulation of agents . It is configured in the same way as the one used in the service grid Sidecar identical . When we create or change Gateway or VirtualService when ,Istio Pilot The controller will detect the change , The controller will convert this information into Envoy Configure and send it to the relevant agents , Include IngressGateway Inside Envoy.

apiVersion: apps/v1
kind: Deployment
metadata:
  labels:
    app: istio-ingressgateway
    istio: ingressgateway
    release: istio
  name: istio-ingressgateway
  namespace: istio-system
spec:
  selector:
    matchLabels:
      app: istio-ingressgateway
      istio: ingressgateway
  strategy:
    rollingUpdate:
      maxSurge: 100%
      maxUnavailable: 25%
  template:
    metadata:
      annotations:
        prometheus.io/path: /stats/prometheus
        prometheus.io/port: "15090"
        prometheus.io/scrape: "true"
        sidecar.istio.io/inject: "false"
      labels:
        app: istio-ingressgateway
        chart: gateways
        heritage: Tiller
        istio: ingressgateway
        release: istio
        service.istio.io/canonical-name: istio-ingressgateway
        service.istio.io/canonical-revision: latest
    spec:
      affinity:
        nodeAffinity:
          preferredDuringSchedulingIgnoredDuringExecution:
          - preference:
              matchExpressions:
              - key: kubernetes.io/arch
                operator: In
                values:
                - amd64
            weight: 2
          - preference:
              matchExpressions:
              - key: kubernetes.io/arch
                operator: In
                values:
                - ppc64le
            weight: 2
          - preference:
              matchExpressions:
              - key: kubernetes.io/arch
                operator: In
                values:
                - s390x
            weight: 2
          requiredDuringSchedulingIgnoredDuringExecution:
            nodeSelectorTerms:
            - matchExpressions:
              - key: kubernetes.io/arch
                operator: In
                values:
                - amd64
                - ppc64le
                - s390x
      containers:
      - args:
        - proxy
        - router
        - --domain
        - $(POD_NAMESPACE).svc.cluster.local
        - --proxyLogLevel=warning
        - --proxyComponentLogLevel=misc:error
        - --log_output_level=default:info
        - --serviceCluster
        - istio-ingressgateway
        - --trust-domain=cluster.local
        env:
        - name: JWT_POLICY
          value: third-party-jwt
        - name: PILOT_CERT_PROVIDER
          value: istiod
        - name: CA_ADDR
          value: istiod.istio-system.svc:15012
        - name: NODE_NAME
          valueFrom:
            fieldRef:
              apiVersion: v1
              fieldPath: spec.nodeName
        - name: POD_NAME
          valueFrom:
            fieldRef:
              apiVersion: v1
              fieldPath: metadata.name
        - name: POD_NAMESPACE
          valueFrom:
            fieldRef:
              apiVersion: v1
              fieldPath: metadata.namespace
        - name: INSTANCE_IP
          valueFrom:
            fieldRef:
              apiVersion: v1
              fieldPath: status.podIP
        - name: HOST_IP
          valueFrom:
            fieldRef:
              apiVersion: v1
              fieldPath: status.hostIP
        - name: SERVICE_ACCOUNT
          valueFrom:
            fieldRef:
              fieldPath: spec.serviceAccountName
        - name: CANONICAL_SERVICE
          valueFrom:
            fieldRef:
              fieldPath: metadata.labels['service.istio.io/canonical-name']
        - name: CANONICAL_REVISION
          valueFrom:
            fieldRef:
              fieldPath: metadata.labels['service.istio.io/canonical-revision']
        - name: ISTIO_META_WORKLOAD_NAME
          value: istio-ingressgateway
        - name: ISTIO_META_OWNER
          value: kubernetes://apis/apps/v1/namespaces/istio-system/deployments/istio-ingressgateway
        - name: ISTIO_META_MESH_ID
          value: cluster.local
        - name: ISTIO_META_ROUTER_MODE
          value: sni-dnat
        - name: ISTIO_META_CLUSTER_ID
          value: Kubernetes
        image: docker.io/istio/proxyv2:1.7.3
        name: istio-proxy
        ports:
        - containerPort: 15021
        - containerPort: 8080
        - containerPort: 8443
        - containerPort: 15443
        - containerPort: 15090
          name: http-envoy-prom
          protocol: TCP
        readinessProbe:
          failureThreshold: 30
          httpGet:
            path: /healthz/ready
            port: 15021
            scheme: HTTP
          initialDelaySeconds: 1
          periodSeconds: 2
          successThreshold: 1
          timeoutSeconds: 1
        resources:
          limits:
            cpu: 2000m
            memory: 1024Mi
          requests:
            cpu: 100m
            memory: 128Mi
        securityContext:
          allowPrivilegeEscalation: false
          capabilities:
            drop:
            - ALL
          privileged: false
          readOnlyRootFilesystem: true
        volumeMounts:
        - mountPath: /etc/istio/proxy
          name: istio-envoy
        - mountPath: /etc/istio/config
          name: config-volume
        - mountPath: /var/run/secrets/istio
          name: istiod-ca-cert
        - mountPath: /var/run/secrets/tokens
          name: istio-token
          readOnly: true
        - mountPath: /var/run/ingress_gateway
          name: gatewaysdsudspath
        - mountPath: /etc/istio/pod
          name: podinfo
        - mountPath: /etc/istio/ingressgateway-certs
          name: ingressgateway-certs
          readOnly: true
        - mountPath: /etc/istio/ingressgateway-ca-certs
          name: ingressgateway-ca-certs
          readOnly: true
      securityContext:
        fsGroup: 1337
        runAsGroup: 1337
        runAsNonRoot: true
        runAsUser: 1337
      serviceAccountName: istio-ingressgateway-service-account
      volumes:
      - configMap:
          name: istio-ca-root-cert
        name: istiod-ca-cert
      - downwardAPI:
          items:
          - fieldRef:
              fieldPath: metadata.labels
            path: labels
          - fieldRef:
              fieldPath: metadata.annotations
            path: annotations
        name: podinfo
      - emptyDir: {}
        name: istio-envoy
      - emptyDir: {}
        name: gatewaysdsudspath
      - name: istio-token
        projected:
          sources:
          - serviceAccountToken:
              audience: istio-ca
              expirationSeconds: 43200
              path: istio-token
      - configMap:
          name: istio
          optional: true
        name: config-volume
      - name: ingressgateway-certs
        secret:
          optional: true
          secretName: istio-ingressgateway-certs
      - name: ingressgateway-ca-certs
        secret:
          optional: true
          secretName: istio-ingressgateway-ca-certs

We are IngressGateway What you have to care about in deployment is SSL certificate . In order to be able to access gateway Certificates in resources , Please make sure the certificate is installed correctly .

 volumeMounts:
        - mountPath: /etc/istio/ingressgateway-certs
          name: ingressgateway-certs
          readOnly: true
        - mountPath: /etc/istio/ingressgateway-ca-certs
          name: ingressgateway-ca-certs
          readOnly: true
     
      volumes:
      - name: ingressgateway-certs
        secret:
          optional: true
          secretName: istio-ingressgateway-certs
      - name: ingressgateway-ca-certs
        secret:
          optional: true
          secretName: istio-ingressgateway-ca-certs 

because istio-ingressgateway It mainly deals with boundary flow , So you have to create LoadBalancer Type of service, All external traffic enters the cluster through this cloud load balancer , The load balancer routes traffic to istio-ingressgateway Of envoy Containers .

apiVersion: v1
kind: Service
metadata:
  labels:
    app: istio-ingressgateway
    istio: ingressgateway
    release: istio
  name: istio-ingressgateway
  namespace: istio-system
spec:
  ports:
  - name: status-port
    port: 15021
    targetPort: 15021
  - name: http2
    port: 80
    targetPort: 8080
  - name: https
    port: 443
    targetPort: 8443
  - name: tls
    port: 15443
    targetPort: 15443
  selector:
    app: istio-ingressgateway
    istio: ingressgateway
  type: LoadBalancer

For performance reasons , We should say .spec.externalTrafficPolicy Set to local Pattern , Avoid two jumps .

Others include HPA,PDB as well as RBAC And so on .

More than one cluster Gateway

Sometimes create multiple ingress gateway It's also very useful. . for example , In a very large cluster , There are thousands of services , You may not want to drive all external traffic through a cloud load balancer and a deployment , But want to share the load horizontally .

Deploy multiple Gateway, Relatively simple , Refer to the previous step to deploy , Notice to change the name , Copy multiple deployments .

So how do we choose ingress gateway that ？ adopt selector choice . as follows ：

metadata:
  name: gateway
spec:
  selector:
    istio: second-istio-ingressgateway

To configure

Ingress Gateway Does not contain any traffic routing configuration .Ingress The routing of traffic uses Istio Routing rules to configure , It's exactly the same as an internal service request .

Let's see how to do it for HTTP The flow in 80 Configuration on port Gateway.

1. establish Istio Gateway：

$ kubectl apply -f - <<EOF
apiVersion: networking.istio.io/v1alpha3
kind: Gateway
metadata:
  name: httpbin-gateway
spec:
  selector:
    istio: ingressgateway # use Istio default gateway implementation
  servers:
  - port:
      number: 80
      name: http
      protocol: HTTP
    hosts:
    - "httpbin.example.com"
EOF

1. For adoption Gateway To configure the route for the entry traffic of ：

$ kubectl apply -f - <<EOF
apiVersion: networking.istio.io/v1alpha3
kind: VirtualService
metadata:
  name: httpbin
spec:
  hosts:
  - "httpbin.example.com"
  gateways:
  - httpbin-gateway
  http:
  - match:
    - uri:
        prefix: /status
    - uri:
        prefix: /delay
    route:
    - destination:
        port:
          number: 8000
        host: httpbin
EOF

Already been httpbin The service created A virtual service To configure , Contains two routing rules , Allow traffic to flow to the path /status and /delay.

gateways The list specifies which requests are allowed to pass through httpbin-gateway gateway . All other external requests are rejected and returned 404 Respond to .

Security

Use SDS by Gateway Provide HTTPS Encryption support

You can configure the TLS Ingress Gateway , Let it come from Ingress Gateway Agent through SDS Obtain the credentials .Ingress Gateway Agents and Ingress Gateway In the same Pod Run in , monitor Ingress Gateway Created in the namespace Secret. stay Ingress Gateway Enable SDS It has the following advantages ：

• Ingress Gateway No need to restart , You can dynamically add 、 Delete or update the key / Certificate pairs and root certificates .
• No load required Secret volume . Created kubernetes`Secret after , This Secret` Will be Gateway Agent capture , And with the key / Certificate pairs and root certificates are sent to Ingress Gateway .
• Gateway Agents can monitor multiple keys / Certificate to . Just create... For each host name Secret And update the Gateway Definition is fine .

nothing TLS Terminated Ingress Gateway

To configure Ingress Gateway To carry out SNI transparent transmission , Not on incoming requests TLS End . for example ：

apiVersion: networking.istio.io/v1alpha3
kind: Gateway
metadata:
  name: mygateway
spec:
  selector:
    istio: ingressgateway # use istio default ingress gateway
  servers:
  - port:
      number: 443
      name: https
      protocol: HTTPS
    tls:
      mode: PASSTHROUGH
    hosts:
    - nginx.example.com