Istio使用【sidecar注入】

本文使用的版本號：1.4.2

查看默認sidecar配置

kubectl get mutatingwebhookconfiguration istio-sidecar-injector -o yaml | grep "namespaceSelector:" -A5

  namespaceSelector:
    matchLabels:
      istio-injection: enabled
  objectSelector: {}
  reinvocationPolicy: Never
  rules:

可以看出，istio默認sidecar注入規則是，namespace帶有標籤istio-injection: enabled纔會注入sidecar。

查看哪些namespace已經配置注入：

[root@k8s-master istio-1.4.2]# kubectl get namespace -L istio-injection
NAME              STATUS   AGE   ISTIO-INJECTION
default           Active   70d   
ingress-nginx     Active   69d   
istio-system      Active   19h   
kube-node-lease   Active   70d   
kube-public       Active   70d   
kube-system       Active   70d   
naftis            Active   19h   
test-deri         Active   47d 

爲namespace打上注入sidecar標籤：

kubectl label namespace default istio-injection=enabled --overwrite

 默認情況，是沒有設置。

爲namespace設置不注入sidecar

有些k8s系統組件namespace不應該注入sidecar，如kube-system等，參考如下設置

kubectl get mutatingwebhookconfiguration istio-sidecar-injector -o yaml | grep "namespaceSelector:" -A5

  namespaceSelector:
    matchExpressions:
    - key: istio-injection
      operator: NotIn
      values:
      - disabled
  rules:
  - apiGroups:
    - ""

爲namespace打上不注入sidecar標籤:

kubectl label namespace istio-system istio-injection=disabled --overwrite

kubectl get namespace -L istio-injection

NAME           STATUS    AGE       ISTIO-INJECTION
default        Active    18d
istio-system   Active    3d        disabled
kube-public    Active    18d       disabled
kube-system    Active    18d       disabled

查看sidecar配置策略

sidecar配置保存在configmap-istio-sidecar-injector中，更多配置可以在install/kubernetes/helm/istio/charts/sidecarInjectorWebhook/values.yaml中查看。

主要配置，默認策略：

kubectl -n istio-system get configmap istio-sidecar-injector -o jsonpath='{.data.config}' | grep policy:

允許的值爲disabled和enabled。僅當Webhook namespaceSelector匹配目標名稱空間時，才應用默認策略。無法識別的策略導致注入被完全禁用。

注意：①策略爲disabled，但是想要爲POD注入sidecar，增加annotation sidecar.istio.io/inject: "true"即可

  ②策略爲enabled，但是不想要爲POD注入sidecar，增加annotation sidecar.istio.io/inject: "false"即可

apiVersion: apps/v1
kind: Deployment
metadata:
  name: ignored
spec:
  template:
    metadata:
      annotations:
        sidecar.istio.io/inject: "false"
    spec:
      containers:
      - name: ignored
        image: tutum/curl
        command: ["/bin/sleep","infinity"]

手動注入sidecar

爲一個寫好的yaml文件手動注入sidecar，我們可以使用istioctl kube-inject:

istioctl kube-inject -f samples/sleep/sleep.yaml | kubectl apply -f -

默認情況下，這將使用集羣內配置。或者，可以使用配置的本地副本來完成注入。下面命令可以將默認配置導出到文件：

kubectl -n istio-system get configmap istio-sidecar-injector -o=jsonpath='{.data.config}' > inject-config.yaml
kubectl -n istio-system get configmap istio-sidecar-injector -o=jsonpath='{.data.values}' > inject-values.yaml
kubectl -n istio-system get configmap istio -o=jsonpath='{.data.mesh}' > mesh-config.yaml

然後再將文件中配置注入到已建好的YAML中並運行：

istioctl kube-inject \
    --injectConfigFile inject-config.yaml \
    --meshConfigFile mesh-config.yaml \
    --valuesFile inject-values.yaml \
    --filename samples/sleep/sleep.yaml \
    | kubectl apply -f -

 這和第一條命令效果一樣。驗證sidecar已經注入：

kubectl get pod  -l app=sleep
NAME                     READY   STATUS    RESTARTS   AGE
sleep-64c6f57bc8-f5n4x   2/2     Running   0          24s

其它配置：neverInjectSelector/alwaysInjectSelector，參考官網

示例：

apiVersion: v1
kind: ConfigMap
metadata:
  name: istio-sidecar-injector
data:
  config: |-
    policy: enabled
    neverInjectSelector:
      - matchExpressions:
        - {key: openshift.io/build.name, operator: Exists}
      - matchExpressions:
        - {key: openshift.io/deployer-pod-for.name, operator: Exists}
    template: |-
      initContainers:
...

配置優先級

如果POD配置了註解、neverInjectSelector/alwaysInjectSelector也都配置了，默認策略也配置了，那麼他們之間的優先級參考如下：

Pod Annotations → NeverInjectSelector → AlwaysInjectSelector → Default Policy

卸載自動注入sidecar

• 卸載istio中sidecar組件

kubectl delete mutatingwebhookconfiguration istio-sidecar-injector
kubectl -n istio-system delete service istio-sidecar-injector
kubectl -n istio-system delete deployment istio-sidecar-injector
kubectl -n istio-system delete serviceaccount istio-sidecar-injector-service-account
kubectl delete clusterrole istio-sidecar-injector-istio-system
kubectl delete clusterrolebinding istio-sidecar-injector-admin-role-binding-istio-system

• 刪除某個namespace自動注入

kubectl label namespace default istio-injection-

 sidecar注入問題

更多可以參考官網.