Propagate readiness status to all datacenters #1826
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This is part of the feature of falling back to remote datacenters when the local one is unhealthy during publishing. Considering that hermes-frontend has access only to ZooKeeper in its local datacenter, it needs to have information there on the readiness status of all datacenters to select only those that are ready. Before this change, only the readiness status of the local datacenter was stored in the local ZooKeeper.
moscicky
approved these changes
Feb 29, 2024
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very smooth change. I would only suggest to mention the migration process (or lack of it) and whether the change is safe to rollback in the PR description. As far as I understand defaults would always return ready so we can just mention that that:
- true values will be persisted in ZK on first save
- old readiness path should be removed manually because it will become orphaned
| @@ -52,7 +52,6 @@ public int hashCode() { | |||
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| public enum ReadinessStatus { | |||
| READY, | |||
| NOT_READY, | |||
| UNDEFINED | |||
| NOT_READY | |||
Good point. Added. |
szczygiel-m
approved these changes
Mar 4, 2024
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Intro
This is part of the feature of falling back to remote datacenters when the local one is unhealthy during publishing. Considering that hermes-frontend has access only to ZooKeeper in its local datacenter, it needs to have information there on the readiness status of all datacenters to select only those that are ready. Before this change, only the readiness status of the local datacenter was stored in the local ZooKeeper.
Migration
/datacenter-readiness) to store readiness status, instead of using the old path (/frontend/readiness). Thus, rollbacks to older versions are possible without any additional changes./datacenter-readiness) is populated on the first and subsequent readiness status changes. Versions including this change do not respect values set in the previous path (/frontend/readiness). If the new path does not exist or is empty, Hermes assumes that all datacenters are ready.