Skip to content

Fix MDS crash when securityContext sets a different runAsUser#382

Merged
N-o-Z merged 2 commits intomasterfrom
fix/mds-pythonpath-workaround
Feb 25, 2026
Merged

Fix MDS crash when securityContext sets a different runAsUser#382
N-o-Z merged 2 commits intomasterfrom
fix/mds-pythonpath-workaround

Conversation

@N-o-Z
Copy link
Member

@N-o-Z N-o-Z commented Feb 25, 2026 •
edited
Loading

Closes #381

Summary

  • The MDS Docker image (treeverse/mds) installs Python packages with pip install --user into /home/arktika/.local/lib/python3.13/site-packages/
  • When the Helm chart's securityContext sets a different runAsUser, Python resolves the user site-packages directory relative to the new user's home, where no packages exist
  • This causes ModuleNotFoundError: No module named 'pyarrow' at container startup
  • Workaround: Set PYTHONPATH env var in the MDS deployment to explicitly include the arktika user's site-packages path
  • TODO in code: The proper fix is to rebuild the MDS image with packages installed globally (pip install without --user)

How to reproduce

# Works (default user arktika, UID 1000):
docker run --rm --entrypoint python treeverse/mds:0.2.1 -c "import pyarrow"

# Fails (different UID, simulating securityContext.runAsUser):
docker run --rm --user 1001 --entrypoint python treeverse/mds:0.2.1 -c "import pyarrow"
# ModuleNotFoundError: No module named 'pyarrow'

Test plan

  • Deploy the chart with mds.enabled=true and a securityContext.runAsUser different from 1000
  • Verify the MDS pod starts successfully and imports complete without errors

🤖 Generated with Claude Code

N-o-Z and others added 2 commits February 25, 2026 15:26
@N-o-Z @claude
Fix MDS crash when securityContext sets a different runAsUser
ad3043c 
The MDS Docker image installs Python packages under the arktika user's
home directory (~/.local/lib/python3.13/site-packages). When the Helm
chart's securityContext configures a different runAsUser, Python resolves
the user site-packages to a different home directory where no packages
exist, causing "ModuleNotFoundError: No module named 'pyarrow'" at startup.

Add PYTHONPATH env var pointing to the arktika user's site-packages as a
workaround. The proper fix is to rebuild the MDS image with globally
installed packages.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
@N-o-Z @claude
Update CHANGELOG for 1.7.20
9f366dc 
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
@N-o-Z N-o-Z self-assigned this Feb 25, 2026
@N-o-Z N-o-Z requested a review from a team February 25, 2026 20:31
@N-o-Z N-o-Z merged commit 669941c into master Feb 25, 2026
4 checks passed
@N-o-Z N-o-Z deleted the fix/mds-pythonpath-workaround branch February 25, 2026 20:32
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment

Reviewers

@Annaseli Annaseli Annaseli approved these changes

Assignees

@N-o-Z N-o-Z

Labels

None yet

Projects

None yet

Milestone

No milestone

Development

Successfully merging this pull request may close these issues.

MDS Broken deployment

2 participants

@N-o-Z @Annaseli