This commit overhauls the documentation of discovery and cluster coordination,
removing mention of the Zen Discovery module and replacing it with docs for the
new cluster coordination mechanism introduced in 7.0.
Relates #32006
This is related to #36652. In 7.0 we plan to deprecate a number of
settings that make reference to the concept of a tcp transport. We
mostly just have a single transport type now (based on tcp). Settings
should only reference tcp if they are referring to socket options. This
commit updates the settings in the docs. And removes string usages of
the old settings. Additionally it adds a missing remote compress setting
to the docs.
Changes the default of the `node.name` setting to the hostname of the
machine on which Elasticsearch is running. Previously it was the first 8
characters of the node id. This had the advantage of producing a unique
name even when the node name isn't configured but the disadvantage of
being unrecognizable and not being available until fairly late in the
startup process. Of particular interest is that it isn't available until
after logging is configured. This forces us to use a volatile read
whenever we add the node name to the log.
Using the hostname is available immediately on startup and is generally
recognizable but has the disadvantage of not being unique when run on
machines that don't set their hostname or when multiple elasticsearch
processes are run on the same host. I believe that, taken together, it
is better to default to the hostname.
1. Running multiple copies of Elasticsearch on the same node is a fairly
advanced feature. We do it all the as part of the elasticsearch build
for testing but we make sure to set the node name then.
2. That the node.name defaults to some flavor of "localhost" on an
unconfigured box feels like it isn't going to come up too much in
production. I expect most production deployments to at least set the
hostname.
As a bonus, production deployments need no longer set the node name in
most cases. At least in my experience most folks set it to the hostname
anyway.
The docs here incorrectly state that it is okay for a heap dump file to
exist when heap dump path is configured to a fixed filename. This is
incorrect, the JVM will fail to write the heap dump if a heap dump file
already exists at the specified location (see the DumpWriter constructor
DumpWriter::DumpWriter(const char* path) in the JVM source).
On some Linux distributions tmpfiles.d cleans files and
directories under /tmp if they haven't been accessed for
10 days.
This can cause problems for ML as ML is currently the only
component that uses the temp directory more than a few
seconds after startup. If you didn't open an ML job for
10 days and then tried to open one then the temp directory
would have been deleted.
This commit prevents the problem occurring in the case of
Elasticsearch being managed by systemd, as systemd private
temp directories are not subject to periodic cleanup (by
default).
Additionally there are now some docs to warn people about
the risk and suggest a manual mitigation for .tar.gz users.
This is a follow up to a previous change which set the error file path
for the package distributions. The observation here is that we always
set the working directory of Elasticsearch to the root of the
installation (i.e., Elasticsearch home). Therefore, we can specify the
error file path relative to this directory and default it to the logs
directory, similar to the package distributions.
This is a follow up to a previous change which set the heap dump path
for the package distributions. The observation here is that we always
set the working directory of Elasticsearch to to the root of
installation (i.e., Elasticsearch home). Therefore, we can specify the
heap dump path relative to this directory and default it to the data
directory, similar to the package distributions.
This commit reorganizes some of the content in the configuring
Elasticsearch section of the docs. The changes are:
- move JVM options out of system configuration into configuring
Elasticsearch
- move JVM options to its own page of the docs
- move configuring the heap to important Elasticsearch settings
- move configuring the heap to its own page of the docs
- move all important settings to individual pages in the docs
- remove bootstrap.memory_lock from important settings, this is covered
in the swap section of system configuration
Relates #27755
David Turner
Tim Brooks
Nik Everett
Jason Tedor
datosh
David Roberts
simonzheng
Andrew Banchich