Install Istio with the Istio CNI plugin
By default Istio injects an init container, , 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 containers with the NET_ADMIN and NET_RAW capabilities. 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 identifies user application pods with sidecars requiring traffic redirection and sets this up in the Kubernetes pod lifecycle’s network setup phase, thereby removing the for users deploying pods into the Istio mesh. The Istio CNI plugin replaces the functionality provided by the istio-init
container.
Note: The Istio CNI plugin operates as a chained CNI plugin, and it is designed to be used with another CNI plugin, such as PTP or . See compatibility with other CNI plugins for details.
Install Kubernetes with the container runtime supporting CNI and
kubelet
configured with the main plugin enabled via--network-plugin=cni
.- AWS EKS, Azure AKS, and IBM Cloud IKS clusters have this capability.
- Google Cloud GKE clusters have CNI enabled when any of the following features are enabled: network policy, , workload identity, , or dataplane v2.
- OpenShift has CNI enabled by default.
Install Kubernetes with the enabled.
- The Kubernetes documentation highly recommends this for all Kubernetes installations where
ServiceAccounts
are utilized.
- The Kubernetes documentation highly recommends this for all Kubernetes installations where
Install Istio with CNI plugin
In most environments, a basic Istio cluster with CNI enabled can be installed using the following configuration:
This will deploy an istio-cni-node
DaemonSet into the cluster, which installs the Istio CNI plugin binary to each node and sets up the necessary configuration for the plugin. The CNI DaemonSet runs with PriorityClass
.
There are several commonly used install options:
components.cni.namespace=kube-system
configures the namespace to install the CNI DaemonSet.- controls whether to configure the plugin as a chained CNI plugin.
There is a time gap between a node becomes schedulable and the Istio CNI plugin becomes ready on that node. If an application pod starts up during this time, it is possible that traffic redirection is not properly set up and traffic would be able to bypass the Istio sidecar. This race condition is mitigated by a “detect and repair” method. Please take a look at section to understand the implication of this mitigation.
The istio-cni
plugin is expected to work with any hosted Kubernetes version using CNI plugins. The default installation configuration works with most platforms. Some platforms required special installation settings.
- Google Kubernetes Engine
- Red Hat OpenShift 4.2+
Operation details
Upgrade
When upgrading Istio with , the CNI component can be upgraded together with the control plane using one IstioOperator
resource.
When upgrading Istio with canary upgrade, because the CNI component runs as a cluster singleton, it is recommended to operate and upgrade the CNI component separately from the revisioned control plane. The following IstioOperator
can be used to operate the CNI component independently.
When installing revisioned control planes with the CNI component enabled, values.istio_cni.enabled
needs to be set, so that sidecar injector does not inject the istio-init
init container.
The CNI plugin at version 1.x
is compatible with control plane at version 1.x-1
, 1.x
, and 1.x+1
, which means CNI and control plane can be upgraded in any order, as long as their version difference is within one minor version.
The Istio CNI DaemonSet installs the CNI network plugin on every node. However, a time gap exists between when the DaemonSet pod gets scheduled onto a node, and the CNI plugin is installed and ready to be used. There is a chance that an application pod starts up during that time gap, and the kubelet
has no knowledge of the Istio CNI plugin. The result is that the application pod comes up without Istio traffic redirection and bypasses Istio sidecar.
Traffic redirection parameters
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. You can adjust traffic redirection parameters using the same pod annotations as normal, such as ports and IP ranges to be included or excluded from redirection. See for available parameters.
The Istio CNI plugin may cause networking connectivity problems for any application init containers. When using Istio CNI, starts an injected pod with the following steps:
- The Istio CNI plugin sets up traffic redirection to the Istio sidecar proxy within the pod.
- All init containers execute and complete successfully.
- The Istio sidecar proxy starts in the pod along with the pod’s other containers.
Init containers execute before the sidecar proxy starts, which can result in traffic loss during their execution. Avoid this traffic loss with one of the following settings:
- Set the
uid
of the init container to1337
usingrunAsUser
.1337
is the . Traffic sent by thisuid
is not captured by the Istio’siptables
rule. Application container traffic will still be captured as usual. - Set the
traffic.sidecar.istio.io/excludeOutboundIPRanges
annotation to disable redirecting traffic to any CIDRs the init containers communicate with.
You must use the runAsUser 1337
workaround if DNS proxying is enabled, and an init container sends traffic to a host name which requires DNS resolution.
Please use traffic capture exclusions with caution, since the IP/port exclusion annotations not only apply to init container traffic, but also application container traffic. i.e. application traffic sent to the configured IP/port will bypass the Istio sidecar.
Compatibility with other CNI plugins
The Istio CNI plugin maintains compatibility with the same set of CNI plugins as the current istio-init
container which requires the NET_ADMIN
and NET_RAW
capabilities.
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 in the pod’s network namespace).
The Istio CNI plugin should not interfere with the operations of the base CNI plugin that configures the pod’s networking setup, although not all CNI plugins have been validated.