Handle zen1 minimum_master_nodes special case for 2->1 masters #1551
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Instead of always updating zen1 before removing a master node, which can lead to split brain scenarios, make sure we update zen1 if we are moving from 2 to 1 master nodes. In other scenarios (eg. 3->2), we want to update minimum_master_nodes after the node is removed. This works fine as long as we remove one master at a time. We check the actual running master pods in the cluster to determine if we are downscaling a master when 2 masters are currently running. This is not a perfect solution since we are relying on potentially out-of-date k8s cached information, but we cannot do something 100% realtime perfect.
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Jenkins test this please. |
pebrc
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Aug 12, 2019
operators/pkg/controller/elasticsearch/driver/downscale_test.go
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Instead of always updating zen1 before removing a master node, which can
lead to split brain scenarios, make sure we update zen1 if we are moving
from 2 to 1 master nodes.
In other scenarios (eg. 3->2), we want to update minimum_master_nodes
after the node is removed. This works fine as long as we remove one
master at a time.
We check the actual running master pods in the cluster to determine if
2 masters are currently running.
This is not a perfect solution since we are relying on potentially
out-of-date k8s cached information, but we cannot do something 100%
realtime perfect.
Relates #1281.
Requires masters to be downscaled one by one to pass E2E tests (implemented in #1549).