2026-08-17 15:59:00 +08:00
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# Runbook: controlled network change
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## Purpose
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Apply a controlled network configuration change (DNS records, firewall, LAN
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gateway, VLAN) with impact assessment, approval, and a rollback path.
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## Scope
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- Applicable: PowerDNS zone records, `us4` firewalld allowlist, LAN gateway/VLAN/DNS changes, WireGuard.
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- Not applicable: SSH access-policy changes (see `AGENTS.md` §SSH access safety — mandatory lockout-risk procedure).
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2026-08-17 17:36:39 +08:00
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## Ownership
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- Owner: personal ops (Windy)
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- Last reviewed: 2026-08-17
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- Related systems: PowerDNS / us4 firewalld / LAN gateway / WireGuard
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2026-08-17 15:59:00 +08:00
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## Preconditions
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- A change record (Linear `vps` issue) describes the change, its reason, and rollback.
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- Read-only impact assessment done (current config captured, blast radius known).
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## Safety
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- Never change DNS or network config without a change record and approval.
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- Capture the current config first; never delete existing config as the first action.
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- For DNS: record the current record values and TTL before editing.
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- For firewall: retain an independent SSH rollback session before applying (see `ansible-operations.md` §us4).
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## Procedure
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### Step 1 — Assess and capture
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**Action** — capture the current state (e.g. `dig` for DNS, `--check --diff` for firewall, `show` for gateway).
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**Expected** — a baseline of current config and an identified blast radius.
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**Decision** — change fully specified with rollback → Step 2; missing → `STOP`.
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### Step 2 — Approve
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**Action** — confirm approval is recorded in the issue/change record.
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**Decision** — approved → Step 3; not approved → `STOP`.
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### Step 3 — Change
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**Action** — apply the single change (edit the record, run the gated playbook, or change gateway config) and only that change.
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**Expected** — the new value/state is in effect.
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**Verification** — re-query/verify the new state and confirm dependent services still pass health.
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**Rollback** — restore the captured prior config and re-verify.
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## Troubleshooting
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### Troubleshooting A — Change broke dependent service
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- Evidence: health report / endpoint failure.
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- Allowed: roll back to the captured prior config.
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- Next: verify; if still broken, escalate.
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## Final Verification
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- New state verified; dependent services healthy.
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- Change and outcome recorded in the issue.
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## References
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- [`ansible-operations.md`](ansible-operations.md)
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- [`rollback.md`](rollback.md)
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- [`network-recovery.md`](network-recovery.md)
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