FirecrackerVM drive not working if /var/lib and /var/cache on two sep…

[olethanh]

…arate partions

Similar issue to #682 That was merged inside #686

We have fixed a variation of this alread but this one triggered for additional volumes only

Explanation:
The prepare step for jailer is failing because it attempt create a hardlink to a file between the CACHE and EXECUTION dir which is not allowed between separate partition

Related ClickUp, GitHub or Jira tickets : ALEPH-238

Self proofreading checklist

• The new code clear, easy to read and well commented.
• New code does not duplicate the functions of builtin or popular libraries.
• An LLM was used to review the new code and look for simplifications.
• New classes and functions contain docstrings explaining what they provide.

Changes

Solution: Make a hardlink
Similiarly to the previous resolution, we cannot make a symlink as it is not accessible inside the jailer enclave

How to test

Gave CACHE an EXECUTION directory on two separate partition and try launching a program with a volume

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 3 lines in your changes missing coverage. Please review.

Project coverage is 62.59%. Comparing base (2dfb42b) to head (6f752dd).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
src/aleph/vm/hypervisors/firecracker/microvm.py	0.00%	3 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #711      +/-   ##
==========================================
- Coverage   62.62%   62.59%   -0.04%     
==========================================
  Files          69       69              
  Lines        6135     6138       +3     
  Branches      497      491       -6     
==========================================
  Hits         3842     3842              
- Misses       2149     2152       +3     
  Partials      144      144              

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.