feat(dcm_deploy): add optional rootless Podman deployment support

[chadcrum]

Summary

• Add dcm_rootless boolean (default false) for optional rootless Podman deployment — rootful remains the default with zero behavior change
• A resolve_rootless_vars phase runs first, creating a dedicated user with lingering, subuid/subgid ranges, and setting internal facts that redirect paths, ownership, and systemd scope
• All 13 quadlet templates use {{ _dcm_wanted_by }} instead of hardcoded multi-user.target
• Every task file updated with become_user, scope, and environment directives for user-scoped systemd/podman operations
• Preflight assertions block rootless on hosts with existing rootful deployments (mutually exclusive)
• New molecule/rootless/ scenario validates template rendering with rootless paths and targets
• CI bumped to ansible-core>=2.16 (required for systemd_service scope parameter)

Tested on

RHEL 9.6 (sealusa12) with all providers enabled — 11/12 containers running under user-scoped systemd. ACM provider not started (dummy pull secret, not a deployment defect). Full QE validation: systemd units, file ownership, port publishing, container DNS, health checks, namespace isolation, cgroup hierarchy, SELinux contexts, idempotency, and service restart resilience — all pass.

Jira

FLPATH-4169

Test plan

• molecule test — default (rootful) scenario passes
• molecule test -s rootless — rootless scenario passes
• ansible-playbook verify_compose_alignment.yml — compose alignment
• yamllint -s . + ansible-lint — clean
• Deploy rootless on RHEL 9 host with dcm_rootless: true
• Verify all containers run under user-scoped systemd
• Verify no rootful artifacts in /etc/containers/systemd/

🤖 Generated with Claude Code

[testetson22]

🤖 AI Code Review

PR Review: #3 — feat(dcm_deploy): add optional rootless Podman deployment support
Repo: dcm-project/quadlet-deploy
Author: chadcrum
Verdict: ✅ APPROVE
Files changed: 31 (+584, -21)

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Gate Checks

Gate	Status
PR Description Quality	✅ Comprehensive summary, tested-on section, Jira link, detailed test plan
CI Status	✅ All 7 checks passing
Single Concern	✅ All changes relate to rootless Podman deployment support
Reasonable Scope	✅ 584 lines is moderate; most additions are systematic become/scope updates
No Secrets in Diff	✅ No credentials found
Draft Status	✅ Not a draft

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Findings Summary

Severity	Count
Critical	0
High	0
Medium	1
Low	2

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Medium Issues

• roles/dcm_deploy/tasks/resolve_rootless_vars.yml:47-53 — The subordinate UID/GID range 231072:65536 is hardcoded. On systems with existing subuid allocations, this could conflict with other rootless users or services. Fix: Consider making the starting UID configurable via dcm_rootless_subuid_start with a sensible default, or document that administrators should verify no conflicts exist before deployment.

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Low Issues

• roles/dcm_deploy/tasks/resolve_rootless_vars.yml:68-72 — The lingering check uses stat then conditional command, but loginctl enable-linger is idempotent. Could simplify, but current implementation is correct and explicit.

• PR description test plan — One unchecked item: "`[ ] Verify all containers run under user-scoped systemd"". The "Tested on" section describes this verification was done; appears to be a checklist cosmetic oversight.

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Positive Observations

✅ Architecture: Clean separation via internal facts (_dcm_* prefix convention) allows existing templates and tasks to work unchanged. The resolve_rootless_vars phase is elegant.

✅ Security: Proper service user setup with system: true, /sbin/nologin shell, and 0700 home directory permissions. Environment file at 0600.

✅ Error Handling: Preflight assertions catch mixed rootful/rootless deployments early with clear error messages. Proper wait_for on XDG_RUNTIME_DIR.

✅ Testing: New molecule/rootless/ scenario with comprehensive assertions on paths, ownership, and systemd targets. Existing default scenario updated to assert rootful behavior.

✅ Documentation: Excellent updates to README.md and CLAUDE.md explaining the feature, path differences, requirements, and limitations.

✅ Ansible Best Practices: All modules use FQCN, proper become_user/scope/environment directives, appropriate handler conditionals.

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Recommendation

Ready to merge. The rootless implementation is well-designed, thoroughly tested, and properly documented. The medium-severity finding about hardcoded subuid ranges is a hardening suggestion rather than a blocker — the chosen range (231072) is unlikely to conflict in practice and follows common conventions.

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ℹ️ Auto-merge: Skipped — repo not on auto-merge allowlist.

[testetson22]

well, I got the bot to work directly from my local repo using my creds without any effort.

[hardengl]

@testetson22 nice!

[chadcrum]

Good catch on the subuid range. 231072:65536 is the conventional second allocation slot for rootless podman — collision is unlikely on single-purpose DCM hosts, and any system with custom subuid allocations would need to review these values regardless of whether they're in a variable or hardcoded.

The linger check is intentional — avoids a changed report on every run, which keeps idempotency clean.

I'll fix the test plan checkbox.