Fix the e2e case where we download the go-getter bomb.zip test file, which
is being removed on main. We can still get it from the version tag - yay git!
* artifact: protect against unbounded artifact decompression
Starting with 1.5.0, set defaut values for artifact decompression limits.
artifact.decompression_size_limit (default "100GB") - the maximum amount of
data that will be decompressed before triggering an error and cancelling
the operation
artifact.decompression_file_count_limit (default 4096) - the maximum number
of files that will be decompressed before triggering an error and
cancelling the operation.
* artifact: assert limits cannot be nil in validation
This PR fixes the artifact sandbox (new in Nomad 1.5) to allow downloading
artifacts into the shared 'alloc' directory made available to each task in
a common allocation. Previously we assumed the 'alloc' dir would be mounted
under the 'task' dir, but this is only the case in fs isolation: chroot; in
other modes the alloc dir is elsewhere.
* client: sandbox go-getter subprocess with landlock
This PR re-implements the getter package for artifact downloads as a subprocess.
Key changes include
On all platforms, run getter as a child process of the Nomad agent.
On Linux platforms running as root, run the child process as the nobody user.
On supporting Linux kernels, uses landlock for filesystem isolation (via go-landlock).
On all platforms, restrict environment variables of the child process to a static set.
notably TMP/TEMP now points within the allocation's task directory
kernel.landlock attribute is fingerprinted (version number or unavailable)
These changes make Nomad client more resilient against a faulty go-getter implementation that may panic, and more secure against bad actors attempting to use artifact downloads as a privilege escalation vector.
Adds new e2e/artifact suite for ensuring artifact downloading works.
TODO: Windows git test (need to modify the image, etc... followup PR)
* landlock: fixup items from cr
* cr: fixup tests and go.mod file
