Immutable Snapshot Containers vs. Live tlmgr Updates for Zero-Downtime PDF Generation

Deployment Strategy for LaTeX Distribution Updates

A document generation service requires a strategy to update the underlying TeX Live distribution without interrupting active PDF requests. The primary constraint is maintaining service availability during the transition, as terminating running TeX engine processes is not permissible.

Two documented approaches present a trade-off between reproducibility and resource efficiency:

• Immutable Snapshot Containers: Utilizing fixed TeX Live snapshots within Docker images. This allows for blue-green deployments to ensure bit-identical builds across environments, though it increases storage overhead due to multiple large images.
• Live tlmgr Updates: Using the TeX Live Manager (tlmgr) within a running container to update packages incrementally. This minimizes storage requirements but introduces the risk of version drift or partial upgrades if a process is interrupted.

There is uncertainty regarding how latexmk handles engine transitions during these updates. Specifically, it is unclear if latexmk -pvc can reliably detect a switch between engines (such as pdfLaTeX to XeLaTeX) and trigger a clean rebuild without leaving auxiliary files that cause inconsistent output.

Technical Questions

• Does latexmk -pvc trigger a full cleanup of intermediate files when the engine configuration changes, or does it rely on incremental processing that may preserve stale artifacts?
• In a live tlmgr update scenario, is there a documented mechanism to ensure all active TeX processes recognize package changes without a full container restart?