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3e61112b1e
There's no need to talk about unwelcome behaviour or power outages here, and it caused at least one user some concern. This commit clarifies the message. Relates #95166
60 lines
2.9 KiB
Text
60 lines
2.9 KiB
Text
[[executable-jna-tmpdir]]
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=== Ensure JNA temporary directory permits executables
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[NOTE]
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This is only relevant for Linux.
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{es} uses the Java Native Access (JNA) library, and another library called
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`libffi`, for executing some platform-dependent native code. On Linux, the
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native code backing these libraries is extracted at runtime into a temporary
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directory and then mapped into executable pages in {es}'s address space. This
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requires the underlying files not to be on a filesystem mounted with the
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`noexec` option.
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By default, {es} will create its temporary directory within `/tmp`. However,
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some hardened Linux installations mount `/tmp` with the `noexec` option by
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default. This prevents JNA and `libffi` from working correctly. For instance,
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at startup JNA may fail to load with an `java.lang.UnsatisfiedLinkerError`
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exception or with a message that says something similar to
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`failed to map segment from shared object`, or `libffi` may report a message
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such as `failed to allocate closure`. Note that the exception messages can
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differ between JVM versions. Additionally, the components of {es} that rely on
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execution of native code via JNA may fail with messages indicating that it is
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`because JNA is not available`.
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To resolve these problems, either remove the `noexec` option from your `/tmp`
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filesystem, or configure {es} to use a different location for its temporary
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directory by setting the <<es-tmpdir,`$ES_TMPDIR`>> environment variable. For
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instance:
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* If you are running {es} directly from a shell, set `$ES_TMPDIR` as follows:
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+
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["source","sh",subs="attributes"]
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--------------------------------------------
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export ES_TMPDIR=/usr/share/elasticsearch/tmp
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--------------------------------------------
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* For installs done through RPM or DEB packages, the environment variable needs
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to be set through the <<sysconfig,system configuration file>>.
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* If you are using `systemd` to run {es} as a service, add the following
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line to the `[Service]` section in a <<systemd,service override file>>:
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+
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[source,text]
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--------------------------------------------
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Environment=ES_TMPDIR=/usr/share/elasticsearch/tmp
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--------------------------------------------
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If you need finer control over the location of these temporary files, you can
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also configure the path that JNA uses with the <<set-jvm-options,JVM flag>>
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`-Djna.tmpdir=<path>` and you can configure the path that `libffi` uses for its
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temporary files by setting the `LIBFFI_TMPDIR` environment variable. Future
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versions of {es} may need additional configuration, so you should prefer to set
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`ES_TMPDIR` wherever possible.
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NOTE: {es} does not remove its temporary directory. You should remove leftover
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temporary directories while {es} is not running. It is best to do this
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automatically, for instance on each reboot. If you are running on Linux, you
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can achieve this by using the
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link:https://www.kernel.org/doc/html/latest/filesystems/tmpfs.html[tmpfs] file
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system.
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