Today there are a few places in the transport layer docs where we talk
about communication between nodes _within a cluster_. We also use the
transport layer for remote cluster connections, and these statements
also apply there, but this is not clear from today's docs. This commit
generalises these statements to make it clear that they apply to remote
cluster connections too.
It also adds a link from the docs on configuring TCP retries to the
(deeply-buried) docs on preserving long-lived connections.
Some systems default to a nofile ulimit of 65535. To reduce the pain of
deploying Elasticsearch to such systems, this commit lowers the required
limit from 65536 to 65535.
When a security manager is present, the JVM will cache positive hostname
lookups indefinitely. This can be problematic, especially in the modern
world with cloud services where DNS addresses can change, or
environments using Docker containers where IP addresses could be
considered ephemeral. This behavior impacts cluster discovery,
cross-cluster replication and cross-cluster search, reindex from remote,
snapshot repositories, webhooks in Watcher, external authentication
mechanisms, and the Elastic Stack Monitoring Service. The experience of
watching a DNS lookup change yet not be reflected within Elasticsearch
is a poor experience for users. The reason the JVM has this is guard
against DNS cache posioning attacks. Yet, there is already a defense in
the modern world against such attacks: TLS. With proper certificate
validation, even if a resolver falls prey to a DNS cache poisoning
attack, using TLS would neuter the attack. Therefore we have a policy
with dubious security value that significantly impacts usability. As
such we make the usability/security tradeoff towards usability, since
the security risks are very low. This commit introduces new system
properties that Elasticsearch observes to override the JVM DNS cache
policy.
If the underlying mount point for the JNA temporary directory is mounted
noexec on Linux, then the JVM will not be able to map the native code in
as executable. This will prevent JNA from executing and will prevent
Elasticsearch from being able to execute some functions that rely on
native code (e.g., memory locking, and installing system call
filters). We do not want to get into the business of catching exceptions
and parsing messages towards this because these exception messages can
change on us. We also do not want to jump through a lot of hoops to
check the underlying mount point for noexec. Instead, we will rely on
documentation to address this problem. This commit adds to the important
system configuration section of the docs that the JNA temporary
directory is not on a mount point with the noexec mount option.
We removed the default_fs store type yet the docs still contain a
reference to them. This commit addresses that by removing this
reference, and changing a reference to this section of the docs to
instead refer to mmapfs.
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
JDK 9 has removed JVM options that were valid in JDK 8 (e.g., GC logging
flags) and replaced them with new flags that are not available in JDK
8. This means that a single JVM options file can no longer apply to JDK
8 and JDK 9, complicating development, complicating our packaging story,
and complicating operations. This commit extends the JVM options syntax
to specify the range of versions the option applies to. If the running
JVM matches the range of versions, the flag will be used to start the
JVM otherwise the flag will be ignored.
We implement this parser in Java for simplicity, and with this we start
our first step towards a Java launcher.
Relates #27675
When these docs were moved they should have been moved to the system
configuration docs. This commit does that, and also fixes a missing
heading that broke the docs build.
Previously the bootstrap check for max number of threads was increased
from 2048 to 4096 yet the docs were never adjusted for this change. This
commit addresses this so the docs are in-line with the limit enforced in
the bootstrap check.
Relates #27511
On non-Windows platforms, we ignore the environment variable
JAVA_TOOL_OPTIONS (this is an environment variable that the JVM respects
by default for picking up extra JVM options). The primary reason that we
ignore this because of the Jayatana agent on Ubuntu; a secondary reason
is that it produces an annoying "Picked up JAVA_TOOL_OPTIONS: ..."
output message. When the elasticsearch-env batch script was introduced
for Windows, ignoring this environment variable was deliberately not
carried over as the primary reason does not apply on Windows. However,
after additional thinking, it seems that we should simply be consistent
to the extent possible here (and also avoid that annoying "Picked up
JAVA_TOOL_OPTIONS: ..." on Windows too). This commit causes the Windows
version of elasticsearch-env to also ignore JAVA_TOOL_OPTIONS.
Relates #25968
This commit changes the default heap size to 1 GB. Experimenting with
elasticsearch is often done on laptops, and 1 GB is much friendlier to
laptop memory. It does put more pressure on the gc, but the tradeoff is
a smaller default footprint. Users running in production can (and
should) adjust the heap size as necessary for their usecase.
Our strong recommendation is disabling swap over any other alternative
to avoid the JVM from landing on disk. This commit clarifies the docs in
this regard.
When overriding a systemd configuration via a drop-in file, the
[Service] header is required. This commit adds this to an example
drop-in override in the configuring docs.
Relates #22038
Elasticsearch can be run in a few different ways:
- from the command line on Linux and Windows
- as a service on Linux and Windows
on both 32-bit client and 64-bit server VMs. We strive for a great
out-of-the-box experience any of these combinations but today it is
lacking on 32-bit client JVMs and on the Windows service. There are two
deficiencies that arise:
- on any 32-bit client JVM we fail to start out of the box because we
force the server JVM in jvm.options
- when installing the Windows service, the thread stack size must be
specified in jvm.options
This commit attempts to address these deficiencies.
We should continue to force the server JVM because there are systems
where the server JVM is not active by default (e.g., the 32-bit JDK on
Windows). This does mean that if a user tries to run with a client JVM
they will see a failure message at startup but this is the best that we
can do if we want to continue to force the server JVM. Thus, this commit
at least documents this situation.
To improve the situation with installing the Windows service, this
commit adds a default setting for the thread stack size. This default is
chosen based on the default thread stack size across all 64-bit server
JVMs. This means that if a user tries to run with a 32-bit JVM they
could otherwise see significantly higher memory usage (this situation is
complicated, it's really only on Windows where the extra memory usage is
egregious, but cutting into the 32-bit address space on any system is
bad). So this commit makes it so that the out-of-the-box experience is
improved for the Windows service on 64-bit server JVMs and we document
the need to adjust this setting on 32-bit JVMs.
Again, we are focusing on the out-of-the-box experience here and this
means optimizing for the best experience on any 64-bit server JVM as
this covers the vast majority of the user base. The users that are on
32-bit JVMs will suffer a little bit but at least now any user on any
64-bit server JVM can start Elasticsearch out of the box.
Finally, we fix some references to the jvm.options documentation.
Relates #21920
On Windows the JDK uses `CreateFileW` which has a stupidly high
limit for the number of `Handle`s it can make - `16 * 1024 * 1024`.
So this isn't really a problem on Windows at all.
Closes#20732
This commit fixes the documentation for configuring the Java I/O temp
dir which incorrectly suggested using the -D flag as a parameter on the
command line; these flags have been removed and should now be specified
as arguments to the JVM using either the ES_JAVA_OPTS environment
variable or using the jvm.options configuration file.
Closes#20652
and be much more stingy about what we consider a console candidate.
* Add `// CONSOLE` to check-running
* Fix version in some snippets
* Mark groovy snippets as groovy
* Fix versions in plugins
* Fix language marker errors
* Fix language parsing in snippets
This adds support for snippets who's language is written like
`[source, txt]` and `["source","js",subs="attributes,callouts"]`.
This also makes language required for snippets which is nice because
then we can be sure we can grep for snippets in a particular language.
This commit adds a note regarding the difference in configuration for
the Windows service heap size from any other installation of
Elasticsearch.
Relates #18606
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.
David Turner
Eddie Turizo
James Rodewig
Peter Dyson
Jason Tedor
sandstrom
Kanako Nakai
Nicolas Sierra
Steve Kotsopoulos
Adrien Grand
propulkit
Ryan Ernst
Nik Everett
Itamar Syn-Hershko
Jared Carey
Nikhil Patel
Pascal Borreli
Clinton Gormley
bloublou