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Diagram
Testing Steps
- Install ISTIO - Deploy istio control plane in each cluster. (NOTE - For testing use common root CA). Reference
- Deploy the application is both the clusters as shown in the above figure. (NOTE - Make sure that the istio sidecars are injected to the Service pods) For example use - server- httpbin, client - sleep
- Configure DNS - To provide resolution of service from remote clusters, istio uses its own DNS called istiocoredns which provides the resolution of remote istio services
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4. Add Istio service entry with details of the remote servers ( server service 03 and server service 04) to the cluster where the client is running (For ISTIO multi-cluster communication usage of SNI ports is mandatory at both ends on istio-ingressgateway)
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apiVersion: networking.istio.io/v1alpha3 kind: VirtualService metadata: name: reviews-route spec: hosts: - service01.bar.svc.cluster.local http: - match: - uri: prefix: "/headers" route: - destination: host: serviceserver04.bar.global port: number: 8000 weight: 50 - destination: host: serviceserver01.bar.svc.cluster.local port: number: 8000 weight: 25 - destination: host: serviceserver02.bar.svc.cluster.local port: number: 8000 weight: 25 |
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#!/bin/bash COUNTER=0 while [ $COUNTER -lt 10 ]; do curl -v service01.bar.svc.cluster.local/headers sleep 2 done |
NOTE - Although the service running in an external cluster can be accessed by following the steps above, the failover mechanism is not yet supported by ISTIO (Replicated control plane).
For this scenario, the intent must have the following istio configurations
Cluster | Istio configuration |
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cluster 01 | a. serviceEntry - of service serverservice04 as shown in step 4 b. virtualservice - having entries of serverservice04 (in cluster 02), serverservice01 (cluster 01) and serverservice02 (cluster 01) as shown in step 5 c. configmap - to add stubdomain .global in the coreDNS d. destinationRule - for any restrictions/loadbalancing amongst internal services/hosts |
cluster 02 | a. configmap - to add stubdomain .global in the coreDNS b. destinationRule - for any restrictions/loadbalancing amongst internal services/hosts |
IN PROGRESS......