David Turner 81c443c9de
Deprecate minimum_master_nodes (#37868)
Today we pass `discovery.zen.minimum_master_nodes` to nodes started up in
tests, but for 7.x nodes this setting is not required as it has no effect.
This commit removes this setting so that nodes are started with more realistic
configurations, and deprecates it.
2019-01-30 20:09:15 +00:00

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[[breaking_70_discovery_changes]]
=== Discovery changes
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==== Cluster bootstrapping is required if discovery is configured
The first time a cluster is started, `cluster.initial_master_nodes` must be set
to perform cluster bootstrapping. It should contain the names of the
master-eligible nodes in the initial cluster and be defined on every
master-eligible node in the cluster. See <<discovery-settings,the discovery
settings summary>> for an example, and the
<<modules-discovery-bootstrap-cluster,cluster bootstrapping reference
documentation>> describes this setting in more detail.
The `discovery.zen.minimum_master_nodes` setting is permitted, but ignored, on
7.x nodes.
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==== Removing master-eligible nodes sometimes requires voting exclusions
If you wish to remove half or more of the master-eligible nodes from a cluster,
you must first exclude the affected nodes from the voting configuration using
the <<modules-discovery-adding-removing-nodes,voting config exclusions API>>.
If you remove fewer than half of the master-eligible nodes at the same time,
voting exclusions are not required. If you remove only master-ineligible nodes
such as data-only nodes or coordinating-only nodes, voting exclusions are not
required. Likewise, if you add nodes to the cluster, voting exclusions are not
required.
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==== Discovery configuration is required in production
Production deployments of Elasticsearch now require at least one of the
following settings to be specified in the `elasticsearch.yml` configuration
file:
- `discovery.zen.ping.unicast.hosts`
- `discovery.zen.hosts_provider`
- `cluster.initial_master_nodes`