elasticsearch/docs/reference/setup/sysconfig/executable-jna-tmpdir.asciidoc

[[executable-jna-tmpdir]]
=== JNA temporary directory not mounted with `noexec`

[NOTE]
This is only relevant for Linux.

{es} uses the Java Native Access (JNA) library, and another library called
`libffi`, for executing some platform-dependent native code. On Linux, the
native code backing these libraries is extracted at runtime into a temporary
directory and then mapped into executable pages in {es}'s address space. This
requires the underlying files not to be on a filesystem mounted with the
`noexec` option.

By default, {es} will create its temporary directory within `/tmp`. However,
some hardened Linux installations mount `/tmp` with the `noexec` option by
default. This prevents JNA and `libffi` from working correctly. For instance,
at startup JNA may fail to load with an `java.lang.UnsatisfiedLinkerError`
exception or with a message that says something similar to
`failed to map segment from shared object`. Note that the exception message can
differ amongst JVM versions. Additionally, the components of {es} that rely on
execution of native code via JNA may fail with messages indicating that it is
`because JNA is not available`.

To resolve these problems, either remove the `noexec` option from your `/tmp`
filesystem, or configure {es} to use a different location for its temporary
directory by setting the <<es-tmpdir,`$ES_TMPDIR`>> environment variable. For
instance:

["source","sh",subs="attributes"]
--------------------------------------------
export ES_TMPDIR=/usr/share/elasticsearch/tmp
--------------------------------------------

Alternatively, you can configure the path that JNA uses for its temporary files
with the <<set-jvm-options,JVM flag>> `-Djna.tmpdir=<path>` and you can
configure the path that `libffi` uses for its temporary files with the
`LIBFFI_TMPDIR` environment variable.