Update README.md

README.md

@@ -139,3 +139,40 @@ Currently we do not use health/ready checks.
 ### Tests
 
 We did not implement any unit/e2e tests for this POC.
+
+### Simulation at high scale
+
+To simulate at high scale `leaf-hub-status-sync` component must be replaced with
+[leaf-hub-simulator](https://github.com/open-cluster-management/leaf-hub-status-sync/tree/leaf-hub-simulator).
+
+Please follow the instructions at [leaf-hub-simulator](https://github.com/open-cluster-management/leaf-hub-status-sync/tree/leaf-hub-simulator) to deploy 'leaf-hub-status-sync' simulator.
+
+Pay attention on `NUMBER_OF_SIMULATED_LEAF_HUBS` environment variable - it defines the number of **additional** (simulated) LHs. If the environment variable is not provided or equal to 0, the simulator will behave as the original `leaf-hub-statis-sync`.
+
+The simulation uses the following tools:
+* [CLC simulator](https://github.com/hanqiuzh/acm-clc-scale) - creates, deletes or keeps alive mock managed clusters (ManagedCluster CR).
+* [GRC simulator](https://github.com/open-cluster-management/grc-simulator) - patches policy (Policy CR) compliances.
+
+**Recommendation:** install the above tools on a separate VM and run them with the `nohup` command (`nohup <YOUR COMMAND> &`) to ensure the tools are running even when the terminal to the VM is disconnected.
+
+Before starting the simulation ensure the environment is "clean":
+1. stop sync service at LH - `kubectl scale deployment sync-service-ess -n sync-service --replicas 0`
+1. stop hoh-status-transport-bridge at HoH - `kubectl scale deployment hub-of-hubs-status-transport-bridge -n open-cluster-management --replicas 0`
+1. stop leaf-hub-status-sync at LH - `kubectl scale deployment leaf-hub-status-sync -n open-cluster-management --replicas 0`
+1. clean database tables - `delete from status.managed_clusters`, `delete from status.compliance`
+1. clean sync service storage - you can use [edge-sync-service-client](https://github.com/open-horizon/edge-sync-service-client)
+1 start sync service at LH - `kubectl scale deployment sync-service-ess -n sync-service --replicas 1`
+1. start hoh-status-transport-bridge at HoH - `kubectl scale deployment hub-of-hubs-status-transport-bridge -n open-cluster-management --replicas 1`
+1. start leaf-hub-status-sync at LH - `kubectl scale deployment leaf-hub-status-sync -n open-cluster-management --replicas 1`
+
+You have two options to run CLC simulator:
+1. The "create mock-cluster" mode - it creates the mock managed clusters and will keep them alive in case they weren't created before.
+1. The "keep-alive mode" - it brings back the mock managed clusters to the `Ready` status in case they were created before.
+
+Once all managed clusters are ready you can run GRC simulator to patch policy compliance status periodically.
+
+
+
+
+
+