istio.io/content/docs/setup/kubernetes/additional-setup/cni/index.md

title	description	weight	aliases	keywords
Install Istio with the Istio CNI plugin	Instructions to install and use Istio with the Istio CNI plugin, allowing operators to deploy services with lower privilege.	70	/docs/setup/kubernetes/install/cni	kubernetes cni sidecar proxy network helm

Follow this path to install, configure, and use an Istio mesh using the Istio Container Network Interface (CNI) plugin.

By default Istio injects an initContainer, istio-init, in pods deployed in the mesh. The istio-init container sets up the pod network traffic redirection to/from the Istio sidecar proxy. This requires the user or service-account deploying pods to the mesh to have sufficient Kubernetes RBAC permissions to deploy NET_ADMIN containers. Requiring Istio users to have elevated Kubernetes RBAC permissions is problematic for some organizations' security compliance. The Istio CNI plugin is a replacement for the istio-init container that performs the same networking functionality but without requiring Istio users to enable elevated Kubernetes RBAC permissions.

The Istio CNI plugin performs the Istio mesh pod traffic redirection in the Kubernetes pod lifecycle's network setup phase, thereby removing the NET_ADMIN capability requirement for users deploying pods into the Istio mesh. The Istio CNI plugin replaces the functionality provided by the istio-init container.

Prerequisites

1. Install Kubernetes with the container runtime supporting CNI and kubelet configured with the main CNI plugin enabled via --network-plugin=cni.

   • Kubernetes installations for AWS EKS, Azure AKS, and IBM Cloud IKS clusters have this capability.
   • Google Cloud GKE clusters require that the network-policy feature is enabled to have Kubernetes configured with network-plugin=cni.

2. Install Kubernetes with the ServiceAccount admission controller enabled.

   • The Kubernetes documentation highly recommends this for all Kubernetes installations where ServiceAccounts are utilized.

Installation

1. Determine the Kubernetes environment's CNI plugin --cni-bin-dir and --cni-conf-dir settings.

   1. Refer to the Hosted Kubernetes Usage section for any non-default settings required.

2. Add the --set istio_cni.enabled=true setting to the Istio Installation with Helm procedure to include the installation of the Istio CNI plugin. For example:

   {{< text bash >}} $ helm template install/kubernetes/helm/istio --name istio --namespace istio-system
   --set istio_cni.enabled=true > $HOME/istio.yaml {{< /text >}}

   {{< tip >}} Refer to the full set of istio-cni Helm parameters in the chart's values.yaml. {{< /tip >}}

Example: excluding specific Kubernetes namespaces

The following example configures the Istio CNI plugin to ignore pods in the namespaces istio-system, foo_ns, and bar_ns.

1. Create an Istio manifest with the Istio CNI plugin enabled and override the default configuration of the istio-cni Helm chart's logLevel and excludeNamespaces parameters:

   {{< text bash >}} $ helm template install/kubernetes/helm/istio --name istio --namespace istio-system
   --set istio_cni.enabled=true
   --set istio-cni.logLevel=info
   --set istio-cni.excludeNamespaces={"istio-system,foo_ns,bar_ns"} > $HOME/istio.yaml {{< /text >}}

Helm chart parameters

Option	Values	Default	Description
hub			The container registry to pull the install-cni image.
tag			The container tag to use to pull the install-cni image.
logLevel	panic, fatal, error, warn, info, debug	warn	Logging level for CNI binary.
excludeNamespaces	[]string	[ istio-system ]	List of namespaces to exclude from Istio pod check.
cniBinDir		/opt/cni/bin	Must be the same as the environment's --cni-bin-dir setting (kubelet parameter).
cniConfDir		/etc/cni/net.d	Must be the same as the environment's --cni-conf-dir setting (kubelet parameter).
cniConfFileName		None	Leave unset to auto-find the first file in the cni-conf-dir (as kubelet does). Primarily used for testing install-cni plugin configuration. If set, install-cni will inject the plugin configuration into this file in the cni-conf-dir.

Hosted Kubernetes Usage

Not all hosted Kubernetes clusters are created with the kubelet configured to use the CNI plugin so compatibility with this istio-cni solution is not ubiquitous. The istio-cni plugin is expected to work with any hosted Kubernetes leveraging CNI plugins. The below table indicates the known CNI status of many common Kubernetes environments.

Hosted Cluster Type	Uses CNI	Required Non-default settings
GKE 1.9+ default	N
GKE 1.9+ w/ network-policy	Y	istio-cni.cniBinDir=/home/kubernetes/bin
IKS (IBM cloud)	Y
EKS (AWS)	Y
AKS (Azure)	Y
Red Hat OpenShift 3.10+	Y

GKE setup

1. Refer to the procedure to prepare a GKE cluster for Istio and enable network-policy in your cluster.

   • Note for existing clusters this redeploys the nodes.

2. Install Istio via Helm including these options --set istio_cni.enabled=true --set istio-cni.cniBinDir=/home/kubernetes/bin

Sidecar injection compatibility

The use of the Istio CNI plugin requires Kubernetes pods to be deployed with a sidecar injection method that uses the istio-sidecar-injector configmap created from the Helm installation with the istio_cni.enabled=true. Refer to Istio sidecar injection for details about Istio sidecar injection methods.

The following sidecar injection methods are supported for use with the Istio CNI plugin:

1. Automatic sidecar injection
2. Manual sidecar injection with the istio-sidecar-injector configmap

   1. istioctl kube-inject using the configmap directly:

      {{< text bash >}} $ istioctl kube-inject -f deployment.yaml -o deployment-injected.yaml --injectConfigMapName istio-sidecar-injector $ kubectl apply -f deployment-injected.yaml {{< /text >}}

   2. istioctl kube-inject using a file created from the configmap:

      {{< text bash >}} $ kubectl -n istio-system get configmap istio-sidecar-injector -o=jsonpath='{.data.config}' > inject-config.yaml $ istioctl kube-inject -f deployment.yaml -o deployment-injected.yaml --injectConfigFile inject-config.yaml $ kubectl apply -f deployment-injected.yaml {{< /text >}}

Operational details

The Istio CNI plugin handles Kubernetes pod create and delete events and does the following:

1. Identify Istio user application pods with Istio sidecars requiring traffic redirection
2. Perform pod network namespace configuration to redirect traffic to/from the Istio sidecar

Identifying pods requiring traffic redirection

The Istio CNI plugin identifies pods requiring traffic redirection to/from the accompanying Istio proxy sidecar by checking that the pod meets all of the following conditions:

1. The pod is NOT in a Kubernetes namespace in the configured exclude_namespaces list.
2. The pod has a container named istio-proxy.
3. The pod has more than 1 container.
4. The pod has no annotation with key sidecar.istio.io/inject OR the value of the annotation is true.

Traffic redirection details

To redirect traffic in the application pod's network namespace to/from the Istio proxy sidecar, the Istio CNI plugin configures the namespace's iptables. The following table describes the parameters to the redirect functionality. The default values for the parameters are able to be overridden by setting the corresponding application pod annotation key.

Annotation Key	Values	Default	Description
sidecar.istio.io/interceptionMode	REDIRECT, TPROXY	REDIRECT	The iptables redirect mode to use.
traffic.sidecar.istio.io/includeOutboundIPRanges	<IPCidr1>,<IPCidr2>,...	"*"	Optional comma separated list of IP ranges in CIDR form to redirect to the sidecar proxy. The default value of "*" redirects all traffic.
traffic.sidecar.istio.io/excludeOutboundIPRanges	<IPCidr1>,<IPCidr2>,...		Optional comma separated list of IP ranges in CIDR form to be excluded from redirection. Only applies when includeOutboundIPRanges is "*".
traffic.sidecar.istio.io/includeInboundPorts	<port1>,<port2>,...	Pod's list of containerPorts	Comma separated list of inbound ports for which traffic is to be redirected to the Istio proxy sidecar. The value of "*" redirects all ports.
traffic.sidecar.istio.io/excludeInboundPorts	<port1>,<port2>,...		Comma separated list of inbound ports to be excluded from redirection to the Istio sidecar proxy. Only valid when includeInboundPorts is "*".

Logging

The Istio CNI plugin is run by the container runtime process space, and, therefore, the log entries are added within the kubelet process.

Compatibility with other CNI plugins

The Istio CNI plugin maintains compatibility with the same set of CNI plugins as the current NET_ADMIN istio-init container.

The Istio CNI plugin operates as a chained CNI plugin. This means its configuration is added to the existing CNI plugins configuration as a new configuration list element. See the CNI specification reference for further details. When a pod is created or deleted, the container runtime invokes each plugin in the list in order. The Istio CNI plugin only performs actions to setup the application pod's traffic redirection to the injected Istio proxy sidecar (using iptables in the pod's network namespace).

{{< warning >}} This should have no effect on the operations performed by the base CNI plugin configuring the pod's networking setup, although not all CNI's have been validated. {{< /warning >}}