base-images.md

Base Image Policy

This repository is transitioning away from CentOS 7-era bases toward modern, supported Linux distributions.

Current Policy

• New recipes should prefer modern bases under recipes/bases/.
• Rocky Linux 9 is the default pilot platform for new general-purpose CPU images.
• Legacy CentOS 7 recipes remain in scs/ for compatibility and migration only.
• Docker bootstrap images should be pinned by digest when practical.

Support Tiers

Tier 1

• Rocky Linux 9.x
• Ubuntu 22.04+ when a Debian-family base is needed

Tier 2

• Legacy CentOS 7 recipes already present in scs/
• Existing recipes/ entries still derived from historical CentOS 7 content

Archived

• shub/ definitions
• End-of-life operating systems that are kept only for reproducibility of old analyses

Pilot Modern Base Recipes

Pilot modern bases live in:

• recipes/bases/rockylinux9/rockylinux9_9.4.def
• recipes/bases/rockylinux9/rockylinux9_java17_9.4.def
• recipes/bases/rockylinux9/rockylinux9_conda_9.4.def

These are intended as migration targets for selected recipes/ over time.

Migration Approach

1. Keep existing CentOS 7-based recipes stable for reproducibility.
2. Introduce Rocky Linux 9 replacements for the most-used base stacks first.
3. Migrate a small flagship subset of tools before touching the whole tree.
4. Document runtime differences and dependency changes in each tool CHANGELOG.md.