See this snippet from the logfile
[2019-09-24T13:35:48,085][INFO ][o.e.b.BootstrapChecks ] [eslnx02] bound or publishing to a non-loopback address, enforcing bootstrap checks
[2019-09-24T13:35:48,089][ERROR][o.e.b.Bootstrap ] [eslnx02] node validation exception
[3] bootstrap checks failed
[1]: initial heap size [2147483648] not equal to maximum heap size [4294967296]; this can cause resize pauses and prevents mlockall from locking the entire heap
[2]: memory locking requested for elasticsearch process but memory is not locked
[3]: the default discovery settings are unsuitable for production use; at least one of [discovery.seed_hosts, discovery.seed_providers, cluster.initial_master_nodes] must be configured
See https://www.elastic.co/guide/en/elasticsearch/reference/7.3/bootstrap-checks.html