Use ES_TMPDIR instead of java.io.tmpdir

[pgomulka]

We should ignore java.io.tmpdir and override it with ES_TMPDIR. I think that variable should be taken into account from the beginning of startup scripts (including JavaVersionChecker) and the value should be applied as java option to all java processes.

Java processes started before ES_JAVA_OPTS are parsed (JavaVersionChecker, TempDirectory, JvmOptionParser) can also create temporary files in /tmp if not provided with java.io.tmpdir
Most notably TempDirectory if ES_TMPDIR is not set will create a temporary dir in that directory - trying to find out system default tmp dir.
JavaVersionChecker and TempDirectory are run before JvmOptionParser is executed, hence these cannot know if java.io.tmpdir was set in jvm.options.

[elasticmachine]

Pinging @elastic/es-core-infra (Team:Core/Infra)

[srisatya12]

@pgomulka @rdnm Can I work on this issue?

[oscarmparedes]

Hi, could someone explain how can we set the ES_TMPDIR parameter?, where is that value stored? is it only a environment variable, if so, this variable should be set as environment variable for the Elasticsearch user?, thanks. I am asking this because we found that our elastic environments could not start after setting /dev/shm and /tmp dirs to noexec. Setting this parameter in jvm.options to an Elasticsearch owned dir fixed the issue, but I think setting the environment variable is a better solution. Thanks.

[sankalpawadhiya]

can I start working on it?

[pugnascotia]

We also need to keep in mind #77014, which is very relevant here.