The environment variable CONF_DIR was previously inconsistently used in
our packaging to customize the location of Elasticsearch configuration
files. The importance of this environment variable has increased
starting in 6.0.0 as it's now used consistently to ensure Elasticsearch
and all secondary scripts (e.g., elasticsearch-keystore) all use the
same configuration. The name CONF_DIR is there for legacy reasons yet
it's too generic. This commit renames CONF_DIR to ES_PATH_CONF.
Relates #26197
This commit removes the default path settings for data and logs. With
this change, we now ship the packages with these settings set in the
elasticsearch.yml configuration file rather than going through the
default.path.data and default.path.logs dance that we went through in
the past.
Relates #25408
The setting bootstrap.mlockall is useful on both POSIX-like systems
(POSIX mlockall) and Windows (Win32 VirtualLock). But mlockall is really
a POSIX only thing so the name should not be tied POSIX. This commit
renames the setting to "bootstrap.memory_lock".
Relates #18669
This commit adds a new configuration file jvm.options to centralize and
simplify management of JVM options. This separates the configuration of
the JVM from the packaging scripts (bin/elasticsearch*, bin/service.bat,
and init.d/elasticsearch) simplifying end-user operational management of
custom JVM options.