Remove Zen1

[ywelsch]

Some of these commits will also be backported to 7.0/7.x (#39470) as the cluster.coordination package was making use of some things in discovery.zen and we want to keep 7.x as close as possible to master.

Note to reviewer: Easiest to review commit by commit, ignoring 5e4a0e7.

[elasticmachine]

Pinging @elastic/es-distributed

[DaveCTurner]

Feels good :)

I left a couple of questions. I also found these remaining mentions of Zen:

elasticsearch/test/framework/src/main/java/org/elasticsearch/test/transport/MockTransportService.java

Line 84 in 2b9ee3a

* (for example, @see org.elasticsearch.discovery.zen.ping.unicast.UnicastZenPing, which constructs

elasticsearch/server/src/main/java/org/elasticsearch/cluster/ClusterState.java

Lines 295 to 304 in f8a946e

	/**
	* The node-level `discovery.zen.minimum_master_nodes` setting on the master node that published this cluster state, for use in rolling
	* upgrades from 6.x to 7.x. Once all the 6.x master-eligible nodes have left the cluster, the 7.x nodes use this value to determine how
	* many master-eligible nodes must be discovered before the cluster can be bootstrapped. Note that this method returns the node-level
	* value of this setting, and ignores any cluster-level override that was set via the API. Callers are expected to combine this value
	* with any value set in the cluster-level settings. This should be removed once we no longer need support for {@link Version#V_6_7_0}.
	*/
	public int getMinimumMasterNodesOnPublishingMaster() {
	return minimumMasterNodesOnPublishingMaster;
	}

(wasReadFromDiff() below is also unused)

elasticsearch/server/src/test/java/org/elasticsearch/cluster/coordination/ElasticsearchNodeCommandIT.java

Line 51 in 6a4e69d

@TestLogging("_root:DEBUG,org.elasticsearch.cluster.service:TRACE,org.elasticsearch.discovery.zen:TRACE")

elasticsearch/server/src/test/java/org/elasticsearch/cluster/MinimumMasterNodesIT.java

Line 63 in 448fc84

@TestLogging("_root:DEBUG,org.elasticsearch.cluster.service:TRACE,org.elasticsearch.discovery.zen:TRACE")

[ywelsch]

@DaveCTurner this is ready for review again

[DaveCTurner]

Sorry, found some more:

elasticsearch/server/src/main/java/org/elasticsearch/cluster/coordination/Coordinator.java

Line 88 in d61827d

public static final long ZEN1_BWC_TERM = 0;

elasticsearch/server/src/main/java/org/elasticsearch/discovery/DiscoveryModule.java

Line 69 in 22438b7

public static final String ZEN_DISCOVERY_TYPE = "legacy-zen";

elasticsearch/server/src/main/java/org/elasticsearch/transport/TransportSettings.java

Lines 157 to 159 in 4e4022b

	listSetting("transport.tracer.exclude",
	Arrays.asList("internal:discovery/zen/fd*", "internal:coordination/fault_detection/*", TransportLivenessAction.NAME),
	Function.identity(), Setting.Property.Dynamic, Setting.Property.NodeScope);

elasticsearch/docs/plugins/integrations.asciidoc

Line 197 in d61827d

Protocol dissection for Zen discovery, HTTP and the binary protocol

elasticsearch/docs/reference/getting-started.asciidoc

Lines 251 to 252 in d61827d

[2018-09-13T12:20:08,355][INFO ][o.e.c.s.MasterService ] [localhost.localdomain] zen-disco-elected-as-master ([0] nodes joined)[, ], reason: master node changed {previous [], current [{localhost.localdomain}{B0aEHNagTiWx7SYj-l4NTw}{hzsQz6CVQMCTpMCVLM4IHg}{127.0.0.1}{127.0.0.1:9300}{testattr=test}]}

[2018-09-13T12:20:08,360][INFO ][o.e.c.s.ClusterApplierService] [localhost.localdomain] master node changed {previous [], current [{localhost.localdomain}{B0aEHNagTiWx7SYj-l4NTw}{hzsQz6CVQMCTpMCVLM4IHg}{127.0.0.1}{127.0.0.1:9300}{testattr=test}]}, reason: apply cluster state (from master [master {localhost.localdomain}{B0aEHNagTiWx7SYj-l4NTw}{hzsQz6CVQMCTpMCVLM4IHg}{127.0.0.1}{127.0.0.1:9300}{testattr=test} committed version [1] source [zen-disco-elected-as-master ([0] nodes joined)[, ]]])

[DaveCTurner]

LGTM