[Elasticsearch][8.0.0] deprecated settings avoid Elasticsearch to start

[kuisathaverat]

The discovery.zen.ping.unicast.hosts avoid Elasticsearch to start if you use the 8.0.0 Docker image

{"type": "server", "timestamp": "2019-04-17T13:51:31,328+0000", "level": "WARN", "component": "o.e.b.ElasticsearchUncaughtExceptionHandler", "cluster.name": "elasticsearch", "node.name": "elasticsearch-master-0",  "message": "uncaught exception in thread [main]" , 
"stacktrace": ["org.elasticsearch.bootstrap.StartupException: java.lang.IllegalArgumentException: unknown setting [discovery.zen.ping.unicast.hosts] please check that any required plugins are installed, or check the breaking changes documentation for removed settings",
"at org.elasticsearch.bootstrap.Elasticsearch.init(Elasticsearch.java:163) ~[elasticsearch-8.0.0-SNAPSHOT.jar:8.0.0-SNAPSHOT]",
"at org.elasticsearch.bootstrap.Elasticsearch.execute(Elasticsearch.java:150) ~[elasticsearch-8.0.0-SNAPSHOT.jar:8.0.0-SNAPSHOT]",
"at org.elasticsearch.cli.EnvironmentAwareCommand.execute(EnvironmentAwareCommand.java:86) ~[elasticsearch-8.0.0-SNAPSHOT.jar:8.0.0-SNAPSHOT]",
"at org.elasticsearch.cli.Command.mainWithoutErrorHandling(Command.java:124) ~[elasticsearch-cli-8.0.0-SNAPSHOT.jar:8.0.0-SNAPSHOT]",
"at org.elasticsearch.cli.Command.main(Command.java:90) ~[elasticsearch-cli-8.0.0-SNAPSHOT.jar:8.0.0-SNAPSHOT]",
"at org.elasticsearch.bootstrap.Elasticsearch.main(Elasticsearch.java:115) ~[elasticsearch-8.0.0-SNAPSHOT.jar:8.0.0-SNAPSHOT]",
"at org.elasticsearch.bootstrap.Elasticsearch.main(Elasticsearch.java:92) ~[elasticsearch-8.0.0-SNAPSHOT.jar:8.0.0-SNAPSHOT]",
"Caused by: java.lang.IllegalArgumentException: unknown setting [discovery.zen.ping.unicast.hosts] please check that any required plugins are installed, or check the breaking changes documentation for removed settings",
"at org.elasticsearch.common.settings.AbstractScopedSettings.validate(AbstractScopedSettings.java:531) ~[elasticsearch-8.0.0-SNAPSHOT.jar:8.0.0-SNAPSHOT]",
"at org.elasticsearch.common.settings.AbstractScopedSettings.validate(AbstractScopedSettings.java:476) ~[elasticsearch-8.0.0-SNAPSHOT.jar:8.0.0-SNAPSHOT]",
"at org.elasticsearch.common.settings.AbstractScopedSettings.validate(AbstractScopedSettings.java:447) ~[elasticsearch-8.0.0-SNAPSHOT.jar:8.0.0-SNAPSHOT]",
"at org.elasticsearch.common.settings.AbstractScopedSettings.validate(AbstractScopedSettings.java:418) ~[elasticsearch-8.0.0-SNAPSHOT.jar:8.0.0-SNAPSHOT]",
"at org.elasticsearch.common.settings.SettingsModule.<init>(SettingsModule.java:148) ~[elasticsearch-8.0.0-SNAPSHOT.jar:8.0.0-SNAPSHOT]",
"at org.elasticsearch.node.Node.<init>(Node.java:343) ~[elasticsearch-8.0.0-SNAPSHOT.jar:8.0.0-SNAPSHOT]",
"at org.elasticsearch.node.Node.<init>(Node.java:253) ~[elasticsearch-8.0.0-SNAPSHOT.jar:8.0.0-SNAPSHOT]",
"at org.elasticsearch.bootstrap.Bootstrap$5.<init>(Bootstrap.java:211) ~[elasticsearch-8.0.0-SNAPSHOT.jar:8.0.0-SNAPSHOT]",
"at org.elasticsearch.bootstrap.Bootstrap.setup(Bootstrap.java:211) ~[elasticsearch-8.0.0-SNAPSHOT.jar:8.0.0-SNAPSHOT]",
"at org.elasticsearch.bootstrap.Bootstrap.init(Bootstrap.java:325) ~[elasticsearch-8.0.0-SNAPSHOT.jar:8.0.0-SNAPSHOT]",
"at org.elasticsearch.bootstrap.Elasticsearch.init(Elasticsearch.java:159) ~[elasticsearch-8.0.0-SNAPSHOT.jar:8.0.0-SNAPSHOT]",
"... 6 more"] }