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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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#!/bin/bash COUNTER=0 while [ $COUNTER -lt 10 ]; do curl -v service01.bar.svc.cluster.local/headers sleep 2 done |
NOTE
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-
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Although
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the
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service
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running
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in
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an external
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cluster
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can
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be
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accessed
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by
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following
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the
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steps
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above,
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the
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failover
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mechanism
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is
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not
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yet
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supported
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by
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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......