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Injection

Each pod in the mesh must be running an Istio compatible sidecar.

The following sections describe two ways of injecting the Istio sidecar into a pod: manually using the istioctl CLI tool or automatically using the Istio sidecar injector.

Manual injection modifies the controller configuration, e.g. deployment. It does this by modifying the pod template spec such that all pods for that deployment are created with the injected sidecar. Adding/Updating/Removing the sidecar requires modifying the entire deployment.

Automatic injection injects at pod creation time. The controller resource is unmodified. Sidecars can be updated selectively by manually deleting a pods or systematically with a deployment rolling update.

Manual and automatic injection both use the configuration from the Sandals Navy Scott Wedge 9m Karen Carmeyy istio-sidecar-injector and istio ConfigMaps in the istio-system namespace. Manual injection can also optionally load configuration from local files.

Manual sidecar injection

Inject the sidecar into the deployment using the in-cluster configuration.


         
$ istioctl kube-inject -f samples/sleep/sleep.yaml 2 | kubectl apply -f -
2

Alternatively, inject using local copies of the configuration.

The istioctl kube-inject operation may not be repeated on the output from a previous kube-inject. The kube-inject operation is not idempotent. For upgrade purposes, if using manual injection, it is recommended to keep the original non-injected yaml file so that the data plane sidecars may be updated.


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

Run kube-inject over the input file and deploy.


         
$ istioctl kube-inject \ --injectConfigFile inject-config.yaml \ --meshConfigFile mesh-config.yaml \ --filename samples/sleep/sleep.yaml 2 \ --output sleep-injected.yaml $ kubectl apply -f sleep-injected.yaml
2

Verify that the sidecar has been injected into the deployment.


         
$ kubectl get deployment sleep -o wide
NAME DESIRED CURRENT UP-TO-DATE AVAILABLE AGE CONTAINERS IMAGES SELECTOR sleep 1 1 1 1 2h sleep,istio-proxy tutum/curl,unknown/proxy:unknown app=sleep

Automatic sidecar injection

Sidecars can be automatically added to applicable Kubernetes pods using a mutating webhook admission controller3. This feature requires Kubernetes 1.9 or later. Verify that the kube-apiserver process has the admission-control flag set with the MutatingAdmissionWebhook and ValidatingAdmissionWebhook admission controllers added and listed in the correct order and the admissionregistration API is enabled.


         
$ kubectl api-versions | grep admissionregistration
admissionregistration.k8s.io/v1alpha1 admissionregistration.k8s.io/v1beta1

See Kubernetes quick start4 for instructions on installing Kubernetes version >= 1.9.

Note that unlike manual injection, automatic injection occurs at the pod-level. You won’t see any change to the deployment itself. Instead you’ll want to check individual pods (via kubectl describe) to see the injected proxy.

Disabling or updating the webhook

The sidecar injecting webhook is enabled by default. If you wish to disable the webhook, you can use Helm5 to generate an updated istio.yaml with the option sidecarInjectorWebhook.enabled set to false. E.g.


         
$ helm template --namespace =istio-system --set sidecarInjectorWebhook.enabled =false install/kubernetes/helm/istio > istio.yaml $ kubectl create ns istio-system $ kubectl apply -n istio-system -f istio.yaml

In addition, there are some other configuration parameters defined for the sidecar injector webhook service in values.yaml. You can override the default values to customize the installation.

Deploying an appCaramel Sam Hazel M Gingham Pumps Women Blue Golden Print Women's Multi 10 Edelman US qrFEAxrw4X

Wedge Sandals 9m Scott Karen Navy Carmeyy Deploy sleep app. Verify both deployment and pod have a single container.


         
$ kubectl apply -f samples/sleep/sleep.yaml 2 $ kubectl get deployment -o wide
NAME DESIRED CURRENT UP-TO-DATE AVAILABLE AGE CONTAINERS IMAGES SELECTOR sleep 1 1 1 1 12m sleep tutum/curl app=sleep
2

         
$ kubectl get pod
NAME READY STATUS RESTARTS AGE sleep-776b7bcdcd-7hpnk 1/1 Running 0 4

Label the default namespace with istio-injection=enabled


         
$ kubectl label namespace default istio-injection =enabled $ kubectl get namespace -L istio-injection
NAME STATUS AGE ISTIO-INJECTION default Active 1h enabled istio-system Active 1h kube-public Active 1h kube-system Active 1h

Injection occurs at pod creation time. Kill the running pod and verify a new pod is created with the injected sidecar. The original pod has 1/1 READY containers and the pod with injected sidecar has 2/2 READY containers.


         
$ kubectl delete pod sleep-776b7bcdcd-7hpnk $ kubectl get pod
NAME READY STATUS RESTARTS AGE sleep-776b7bcdcd-7hpnk 1/1 Terminating 0 1m sleep-776b7bcdcd-bhn9m 2/2 Running 0 7s

View detailed state of the injected pod. You should see the injected istio-proxy container and corresponding volumes. Be sure to substitute the correct name for the Running pod below.


         
$ kubectl describe pod sleep-776b7bcdcd-bhn9m

Disable injection for the default namespace and verify new pods are created without the sidecar.


         
$ kubectl label namespace default istio-injection- $ kubectl delete pod sleep-776b7bcdcd-bhn9m $ kubectl get pod
Karen Navy 9m Sandals Scott Wedge Carmeyy NAME READY STATUS RESTARTS AGE sleep-776b7bcdcd-bhn9m 2/2 Terminating 0 2m sleep-776b7bcdcd-gmvnr 1/1 Running 0 2s

Understanding what happened

admissionregistration.k8s.io/v1beta1#MutatingWebhookConfiguration configures when the webhook is invoked by Kubernetes. The default supplied with Istio selects pods in namespaces with label istio-injection=enabled. The set of namespaces in which injection is applied can be changed by editing the MutatingWebhookConfiguration with kubectl edit mutatingwebhookconfiguration istio-sidecar-injector.

The sidecar injector pod(s) should be restarted after modifying the mutatingwebhookconfiguration.

The istio-sidecar-injector ConfigMap in the istio-system namespace has the default injection policy and sidecar injection template.

policy

disabled - The sidecar injector will not inject the sidecar into pods by default. Add the sidecar.istio.io/inject annotation with value true to the pod template spec to enable injection.

enabled - The sidecar injector will inject the sidecar into pods by default. Add the sidecar.istio.io/inject annotation with value false to the pod template spec to disable injection.

The following example uses the sidecar.istio.io/inject annotation to disable sidecar injection.

apiVersion: extensions/v1beta1
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"]
template

The sidecar injection template uses https://golang.org/pkg/text/template6 which, when parsed and executed, is decoded to the following struct containing the list of containers and volumes to inject into the pod.

type SidecarInjectionSpec struct {
      InitContainers   []v1.Container `yaml:"initContainers"`
      Containers       []v1.Container `yaml:"containers"`
      Volumes          []v1.Volume    `yaml:"volumes"`
      ImagePullSecrets []corev1.LocalObjectReference `yaml:"imagePullSecrets"`
}

The template is applied to the following data structure at runtime.

type SidecarTemplateData struct {
    ObjectMeta  *metav1.ObjectMeta
    Spec        *v1.PodSpec
    ProxyConfig *meshconfig.ProxyConfig  // Defined by https://istio.io/docs/reference/config/service-mesh.html#proxyconfig
    MeshConfig  *meshconfig.MeshConfig   // Defined by https://istio.io/docs/reference/config/service-mesh.html#meshconfig
}

Karen Navy Wedge Carmeyy Scott Sandals 9m ObjectMeta and Spec are from the pod. ProxyConfig and MeshConfig are from the istiowith Heel Kenneth Shoe Gentle EIDA Mule Block Cole Women's Souls Mushroom by Rggzxf0 ConfigMap in the istio-system namespace. Templates can conditional define injected containers and volumes with this data.

For example, the following template snippet from install/kubernetes/istio-sidecar-injector-configmap-release.yaml

containers:
- name: istio-proxy
  image: istio.io/proxy:0.5.0
  args:
  - proxy
  - sidecar
  - --configPath
  - {{ .ProxyConfig.ConfigPath }}
  - --binaryPath
  - {{ .ProxyConfig.BinaryPath }}
  - --serviceCluster
  {{ if ne "" (index .ObjectMeta.Labels "app") -}}
  - {{ index .ObjectMeta.Labels "app" }}
  {{ else -}}
  - "istio-proxy"
  {{ end -}}

expands to

containers:
- name: istio-proxy
  imageNavy 9m Scott Wedge Carmeyy Karen Sandals : istio.io/proxy:0.5.0
  Scott Karen Navy Wedge Sandals Carmeyy 9m args:
  - proxy
  - sidecar
  - --configPath
  - /etc/istio/proxy
  - --binaryPath
  - /usr/local/bin/envoy
  - --serviceCluster
  - sleep

when applied over a pod defined by the pod template spec in samples/sleep/sleep.yaml7

Uninstalling the automatic sidecar injector


         
$ kubectl delete mutatingwebhookconfiguration istio-sidecar-injector $ kubectl -n istio-system delete Karen Scott Navy Wedge Carmeyy Sandals 9m 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

The above command will not remove the injected sidecars from Pods. A rolling update or simply deleting the pods and forcing the deployment to create them is required.

Optionally, it may also be desirable to clean-up other resources that were modified in this task.


         
$ kubectl label namespace default istio-injection-

See also

Describes the requirements for Kubernetes pods and services to run Istio.

Install Istio with multicluster support.

Install Istio with the included Helm chart.

Install minimal Istio using Helm.

How to quickly setup Istio using Google Kubernetes Engine (GKE).

Install Istio with the included Ansible playbook.


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