wiki(ingest): vds-kzntsv network-stack mismatch RCA + ifupdown anti-pattern

Incident 2026-05-28 ~05:45–13:52 MSK на vds-kzntsv. ~2.5ч активного outage
+ ~5.5ч на эфемерной статике до окончательного fix хостером.

Revised RCA: наш netplan+systemd-networkd конфликтовал с provider's expected
ifupdown stack. Их start/ipadd procedure ожидает чистый ifupdown и не может
auto-recover когда networkd «держит» eth0. 8 дней работало потому что
networkd сам тянул DHCP. Когда что-то на стороне Rusonyx разорвало
DHCP-binding — auto-recovery не сработала.

Fix: systemctl mask netplan + systemd-networkd* (на running system без stop —
IP и SSH сохранились), Rusonyx ребутнул VM и положил чистый
/etc/network/interfaces.d/ifcfg-eth0 через свой start/ipadd. Netmask /18,
gw 89.253.192.1, чистый ifupdown.

Wiki:
- NEW concepts/vds-kzntsv-dhcp-outage-2026-05-28 — full RCA + recovery
  runbook (эфемерная статика + permanent-fix via ifupdown) + diagnostic
  dot-graph + revised lessons-learned + anti-pattern
- NEW sources/vds-kzntsv-incident-2026-05-28 — timeline 05:25 backup OK →
  08:43 statics → 13:52 final reset; provider's ifcfg-eth0 content; ticket
  text reference
- UPDATE entities/vds-kzntsv — mask /18, ifupdown stack, kernel cmdline
  net.ifnames=0 объясняет eth0 naming, hypervisor hw80, pass-store путь,
  Known issues §
- UPDATE concepts/rusonyx-vps-onboarding-quirks — quirk #9 переписан про
  /18 layout + canonical ifcfg, quirk #10 NEW про ifupdown vs netplan
  stack choice + bootstrap mask commands
- UPDATE index.md + log.md

Tasks:
- STATUS header: incident RESOLVED summary
- NEXT_SESSION: следующая сессия — cleanup netplan-artifacts (optional),
  registry GC (~20G pending), board-viewer-build unhealthy разбор

Memory (out-of-repo): vds-kzntsv-rusonyx-network-recovery переписан с
revised RCA — canonical bootstrap step «mask netplan/networkd» для всех
Rusonyx Ubuntu VDS.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

.wiki/log.md

@@ -23,3 +23,7 @@ Append-only log of wiki operations (ingests, promotions, lints, migrations).
 ## [2026-05-24] ingest | concepts/books-ssh-access — SSH access audit на shared VDS pre-cutover Фазы 3 tenant-split. Retained keys table (1 key, vitya core dev), removed cosmetic dead root key, sshd hardening verified via `sshd -T` (not raw config), fail2ban active 2670 failed/37 banned, only vitya@94.19.247.14 в access log last 7 days. Source: .tasks/books-ssh-audit-shared-vds.md.
 
 ## [2026-05-24] ingest | RUVDS IIS migration + backup pipeline — entities/ruvds-iis-host (NEW, 80.64.31.36 Win Server 2025 Core, 25 SNI bindings, 2/24 hostnames DNS-flipped) + sources/iis-migration-to-ruvds-2026-05-23 (NEW, SSH/scp pivot после SMB-block by home-ISP) + sources/ruvds-backup-daily-kreknin-2026-05-24 (NEW, rclone+SFTP SYSTEM task daily 04:30) + concepts/traefik-acme-json-to-iis-cert-import (NEW, PFX+SNI recipe) + UPDATE concepts/windows-server-2025-core-bootstrap (SMB deprecate, HTTP middlebox warning, HTTP/2 note, backup-strategy + cert-import закрыты) + UPDATE entities/windows-recovery-host (IIS partial-cutover state, imgproxy SPOF carve-out) + UPDATE overview (RUVDS line). Sources: .tasks/iis-migration-to-ruvds.md, .tasks/ruvds-backup-daily-kreknin.md.
+
+## [2026-05-28] ingest | vds-kzntsv DHCP outage postmortem — concepts/vds-kzntsv-dhcp-outage-2026-05-28 (NEW, симптомокартина + диагностический алгоритм + recovery runbook + RCA) + sources/vds-kzntsv-incident-2026-05-28 (NEW, timeline 05:25 backup OK → 08:15 detect → 08:43 statics fix → 08:50 disk GC; ticket text) + UPDATE entities/vds-kzntsv (Доступ §+subnet/gw/hypervisor/DNS resolvers; pass-store вместо .common/secrets; Known issues §NEW with 2026-05-28 incident; Open issues bump GC priority + iputils-ping note) + UPDATE concepts/rusonyx-vps-onboarding-quirks (quirk #9 NEW — gw в /18 надсети + recovery commands). Live session, no raw source ingested.
+
+## [2026-05-28] update | vds-kzntsv DHCP outage post-resolution — после reset хостером в 13:52 MSK выяснилось что root cause — конфликт двух сетевых стеков (netplan+networkd поверх ожидаемого provider's ifupdown). Их `start/ipadd` ожидает чистый ifupdown, не мог auto-recover при разрыве DHCP binding. Resolution: mask netplan+systemd-networkd, reboot, provider положил `/etc/network/interfaces.d/ifcfg-eth0` с /18 netmask. UPDATE concepts/vds-kzntsv-dhcp-outage-2026-05-28 (revised RCA + permanent-fix § + anti-pattern + revised lessons-learned) + UPDATE sources/vds-kzntsv-incident-2026-05-28 (timeline до 14:00 + final config) + UPDATE entities/vds-kzntsv (mask /18, ifupdown stack, kernel cmdline net.ifnames=0) + UPDATE concepts/rusonyx-vps-onboarding-quirks (quirk #9 переписан про /18, quirk #10 NEW про ifupdown vs netplan stack). Memory `vds-kzntsv-rusonyx-network-recovery` переписан с новыми фактами.