The "lcmaps-plugins-mount-under-scratch" plugin allows the admin to setup
per-invocation copies of world-writable directories such as /tmp or /var/tmp.
This plugin will create a temporary directory of the form:
/tmp/glexec_mount_under_scratch_XXXXXX
and subdirectories
/tmp/glexec_mount_under_scratch_MuLdpO:
tmp/
var/tmp
owned by the payload user.
Further, /tmp will map to /tmp/glexec_mount_under_scratch_MuLdpO/tmp
and /var/tmp will map to /tmp/glexec_mount_under_scratch_MuLdpO/var/tmp for
the payload process (and only the payload process).
If /tmp or /var/tmp are on a shared-bind-mount (meaning the parent and child namespace are identical for a subtree), the most specific subtree will be remounted as private.
The above paragraphs are similar for admin-defined directories. The admin can pass:
-path /var/tmp
-path /foo
-path /bar
-path /tmp
as arguments in lcmaps.db to the plugin to remap /var/tmp, /tmp, /foo, and /bar. Note that order does matter! As the source of the mount is in /tmp, /tmp must be listed last in any set of mappings.
If an admin passes one path, then /tmp and /var/tmp are not done by default.
This plugin takes its inspiration from the implementation of the MOUNT_UNDER_SCRATCH parameter in Condor, and is necessary for MOUNT_UNDER_SCRATCH to work with glexec'd jobs. Note the plugin does not cleanup the created directories - that is the responsibility of the invoker; note that this limitation means this plugin only makes sense when /tmp and /var/tmp are job-specific already (i.e., when used with MOUNT_UNDER_SCRATCH).
This code is licensed under the Apache 2.0 license, and is copyrighted by the University of Nebraska-Lincoln.
Some aspects are derived from the Condor source code, copyrighted Red Hat or University of Wisconsin (and contributed by me under the Condor Contributor Licensing Agreement) and also licensed under Apache 2.0.
Enjoy!
Brian Bockelman