dns-cache

name	dns_cache
description	Maintains the ansible/roles/dns_cache Ansible role that enables or disables local DNS caching via dnsmasq, systemd-resolved, or nscd, as part of the Linux SOE. Use when checking or fixing DNS caching configuration.

dns_cache

Maintains ansible/roles/dns_cache/. See docs/ARCHITECTURE.md for the shared conventions (role layout, audit vs. remediate via --check --diff, safety rules, branch + PR contribution workflow).

ansible/roles/dns_cache/README.md documents this role's full configuration surface (every defaults/main.yml variable, with its original inline comments, rendered as a single reference). Read it before proposing or explaining how to configure this role — it reflects the role's actual current defaults even if a variable summary elsewhere in this file has drifted out of sync with the role.

What the role actually does

Encoded in ansible/roles/dns_cache/defaults/main.yml:

• dns_cache_enable defaults false — the role always runs a disable pass first (disable.yml), then, only if enabled, includes exactly one of dnsmasq.yml / nscd.yml / systemd_resolved.yml based on dns_cache_component (default systemd-resolved, recommended on RHEL 10+; dnsmasq recommended on RHEL 9 and earlier per the role's own comment). nscd is not available on RHEL 10+.
• dns_cache_dnsmasq_ttl (default 10) and dns_cache_dnsmasq_local_domain only apply to the dnsmasq path.

This role is sourced from the myllynen/rhel-ansible-roles import (see git log -- ansible/roles/dns_cache) rather than hand-authored for this repo. Unlike the original reference domains (e.g. timesync, usbguard_setup), it applies state declaratively via standard Ansible modules and does not add its own assert-based drift checks on top — an audit here is exactly what --check --diff reports from the underlying modules, nothing more.

What to do

This role is off by default in ansible/configure_rhel.yml — every role there (active or not) is gated by a single configure_rhel_domains list variable (when: "'<name>' in configure_rhel_domains"), and dns_cache isn't in the default value of that list. Nothing needs editing in the playbook itself to turn it on: pass the full desired domain list via -e, e.g. -e '{"configure_rhel_domains": [...the default 20..., "dns_cache"]}' (see .claude/skills/configure_rhel/SKILL.md for the current default list to extend, and why it has to be the full list, not just the addition — -e replaces the variable's value, it doesn't merge into it). --tags dns_cache alone is not enough — the domains list and --tags/--skip-tags are separate, ANDed gates, both verified independently: a role only runs if it's in configure_rhel_domains and matches the requested tags. Some roles (this one — check its defaults/main.yml and task file) also have their own internal enable flag or required variable on top of that, which still needs setting the same as before. Flag all of this to the user before assuming the commands below will do anything.

Audit (read-only, safe to run any time):

ansible-playbook ansible/configure_rhel.yml --tags dns_cache --check --diff

Summarize the diff output and any failed tasks in plain language.

Remediate (modifies the system — only after the user explicitly asks): first summarize what will change from the --check --diff output, then run the same command without --check:

ansible-playbook ansible/configure_rhel.yml --tags dns_cache

Propose a change to the role itself: never edit and commit directly. On a branch named soe/dns_cache/<short-desc>, edit ansible/roles/dns_cache/, validate locally (--syntax-check, ansible-lint roles/dns_cache/, and --check --diff against a real/test host if available), then push and open a PR titled [dns_cache] <what changed> with the --check --diff output in the body. Then stop — a human reviews and merges; see docs/ARCHITECTURE.md's "Contribution workflow".

Notes

• The role's own comment notes /etc/resolv.conf correctness should be checked before/after — pair with resolver_configuration as needed; this role does not manage /etc/resolv.conf itself.

Wiring into the SOE

This role has a row in .claude/skills/soe/SKILL.md's domain table. It's present (not commented out) in ansible/configure_rhel.yml's roles: list, gated by configure_rhel_domains — off by default, on via -e — see the caveat at the top of "What to do" above and .claude/skills/configure_rhel/SKILL.md. It is not referenced by any of the other playbooks (load_balancer_setup.yml, nfs_client_setup.yml, nfs_server_setup.yml, update_rhel.yml, connect_linux.yml) either. This repo no longer uses ansible/site.yml; see docs/ARCHITECTURE.md.