Technology Preview - Istio Service Mesh Application¶

About this task

The Istio Service Mesh application Technology Preview is integrated into StarlingX as a system application.

Istio provides traffic management, observability as well as security as a Kubernetes service mesh. For more information, see https://istio.io/.

StarlingX includes istio-operator container to manage the life cycle management of the Istio components.

The following Istio components are enabled when applying the Istio system application:

Istio data plane - Envoy - Kubernetes side-car proxy
Istio control plane - Istiod - service discovery, configuration and certificate management
Istio gateway - Traffic management of ingress and egress L4-L7 traffic
Istio-cni - Kubernetes CNI plugin

The Kiali (https://kiali.io/) management console for Istio is also integrated with StarlingX, in the Istio system application. It provides management functions and visualizations to the service mesh operation. Metrics and tracing functionalities are not supported at this time.

Procedure

You can install Istio and Kiali on StarlingX from the command line.

Locate the Istio tarball in /usr/local/share/application/helm.

For example:
```
/usr/local/share/application/helm/istio-<version>.tgz
```

Upload the application.

~(keystone_admin)]$ system application-upload /usr/local/share/application/helm/istio-<version>.tgz

Apply the application.

~(keystone_admin)]$ system application-apply istio

Monitor the application status.

~(keystone_admin)]$ watch -n 5 system application-list

~(keystone_admin)]$ watch kubectl get pods -n istio-system

Setup network attachment definition.
```
cat > istio-cni-nad.yaml <<EOF
apiVersion: "k8s.cni.cncf.io/v1"
kind: NetworkAttachmentDefinition
metadata:
 name: istio-cni
EOF
kubectl apply -f istio-cni-nad.yaml
```
CNI is managed by Multus. The NetworkAttachmentDefinition is required in the application namespace in order to invoke the istio-cni plugin.
Enable side car for a particular namespace.
```
kubectl label namespace <namespace> istio-injection=enabled
```
When the istio-injection=enabled label on a namespace is set and the injection webhook is enabled, any new pods that are created in that namespace will automatically have a sidecar added to them.
At this point, you may launch services in the above namespace.

When the user application is deployed, the sidecar container istio-proxy is injected into the user application pod:

Events:
```
Type    Reason     Age   From               Message
----    ------     ----  ----               -------
...
Normal  Created    10s   kubelet            Created container <user app>
Normal  Started    10s   kubelet            Started container <user app>
...
Normal  Created    9s    kubelet            Created container istio-proxy
Normal  Started    8s    kubelet            Started container istio-proxy
```
The istio-proxy sidecar extracts telemetry of all ingress and egress traffic of the user application that can be monitored and available for display in Kiali, and it mediates all ingress and egress traffic of the user application by enforcing policy decisions.

Use Kiali¶

After the Istio application has been installed, you can launch the Kiali management console in a browser.

Get the port of Kiali service.

~(keystone_admin)]$ kubectl get svc -n istio-system kiali -o jsonpath='{.spec.ports[?(@.name=="http")].nodePort}'

Launch Kiali on a browser.

http:<oam-floating-ip>:<kiali_port>/kiali

Get the login token.

~(keystone_admin)]$ kubectl get secret -n istio-system $(kubectl get sa kiali -n istio-system -o jsonpath='{.secrets[0].name}') -o jsonpath='{.data.token}' | base64 -d

Remove Istio application¶

You can remove the Istio application from StarlingX.

Remove pods and their resources.

~(keystone_admin)]$ system application-remove istio

Delete the application.

~(keystone_admin)]$ system application-delete istio

Delete Istio CNI Network Attachment Definition.

~(keystone_admin)]$ kubectl delete -f istio-cni-nad.yaml