Avoid counting votes from master-ineligible nodes #44260
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Today if a master-eligible node is converted to a master-ineligible node it may remain in the voting configuration, meaning that the master node may count its publish responses as an indication that it has properly persisted the cluster state. However master-ineligible nodes do not properly persist the cluster state, so it is not safe to count these votes. This change adjusts `CoordinationState` to take account of this from a safety point of view, and also adjusts the `Coordinator` to prevent such nodes from joining the cluster. Instead, it triggers a reconfiguration to remove from the voting configuration a node that now appears to be master-ineligible before processing its join.
DaveCTurner
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:Distributed Coordination/Cluster Coordination
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Pinging @elastic/es-distributed |
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Backport of #43688, no need for a separate review. |
DaveCTurner
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2019-07-12-prevent-votes-from-master-ineligible-nodes-7x
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Today if a master-eligible node is converted to a master-ineligible node it may
remain in the voting configuration, meaning that the master node may count its
publish responses as an indication that it has properly persisted the cluster
state. However master-ineligible nodes do not properly persist the cluster
state, so it is not safe to count these votes.
This change adjusts
CoordinationStateto take account of this from a safetypoint of view, and also adjusts the
Coordinatorto prevent such nodes fromjoining the cluster. Instead, it triggers a reconfiguration to remove from the
voting configuration a node that now appears to be master-ineligible before
processing its join.
Backport of #43688.