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Author SHA1 Message Date
DongHyeonkaandClaude Opus 5 d0666c5ba0 docs: A-4 — a dead pod reports healthier than a live one
Kubernetes keeps calling the node Ready for forty seconds while users already see failures, and the pod on the powered-off machine stays ready=true because its kubelet can no longer contradict itself. Eviction waits another five minutes, then the StatefulSet refuses to recreate its pod and the replacement Deployment pod cannot schedule because the local-path volume is pinned to the dead node.

Killing the server node instead shows the opposite shape: containerd keeps the workload running while the API server, Traefik and the observability stack disappear, so the outage is the missing path rather than the missing application. Traefik at one replica is the ingress single point of failure.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
2026-09-04 12:25:30 +09:00
15 changed files with 866 additions and 0 deletions
@@ -53,3 +53,77 @@
[ 502295ms] [ERROR] WebSocket connection to 'wss://app2.hyeonworks.com/api/live/ws' failed: Error during WebSocket handshake: Unexpected response code: 400 @ https://app2.hyeonworks.com/public/build/1518.a3f1f690c084a37f01c7.js:362
[ 511625ms] [ERROR] WebSocket connection to 'wss://app2.hyeonworks.com/api/live/ws' failed: Error during WebSocket handshake: Unexpected response code: 400 @ https://app2.hyeonworks.com/public/build/1518.a3f1f690c084a37f01c7.js:362
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[ 626612ms] [ERROR] WebSocket connection to 'wss://app2.hyeonworks.com/api/live/ws' failed: Error during WebSocket handshake: Unexpected response code: 400 @ https://app2.hyeonworks.com/public/build/1518.a3f1f690c084a37f01c7.js:362
[ 639003ms] [ERROR] WebSocket connection to 'wss://app2.hyeonworks.com/api/live/ws' failed: Error during WebSocket handshake: Unexpected response code: 400 @ https://app2.hyeonworks.com/public/build/1518.a3f1f690c084a37f01c7.js:362
[ 655077ms] [ERROR] WebSocket connection to 'wss://app2.hyeonworks.com/api/live/ws' failed: Error during WebSocket handshake: Unexpected response code: 400 @ https://app2.hyeonworks.com/public/build/1518.a3f1f690c084a37f01c7.js:362
[ 674532ms] [ERROR] WebSocket connection to 'wss://app2.hyeonworks.com/api/live/ws' failed: Error during WebSocket handshake: Unexpected response code: 400 @ https://app2.hyeonworks.com/public/build/1518.a3f1f690c084a37f01c7.js:362
[ 677197ms] [ERROR] WebSocket connection to 'wss://app2.hyeonworks.com/api/live/ws' failed: Error during WebSocket handshake: Unexpected response code: 400 @ https://app2.hyeonworks.com/public/build/1518.a3f1f690c084a37f01c7.js:362
[ 696027ms] [ERROR] WebSocket connection to 'wss://app2.hyeonworks.com/api/live/ws' failed: Error during WebSocket handshake: Unexpected response code: 400 @ https://app2.hyeonworks.com/public/build/1518.a3f1f690c084a37f01c7.js:362
[ 709512ms] [ERROR] WebSocket connection to 'wss://app2.hyeonworks.com/api/live/ws' failed: Error during WebSocket handshake: Unexpected response code: 400 @ https://app2.hyeonworks.com/public/build/1518.a3f1f690c084a37f01c7.js:362
[ 727505ms] [ERROR] WebSocket connection to 'wss://app2.hyeonworks.com/api/live/ws' failed: Error during WebSocket handshake: Unexpected response code: 400 @ https://app2.hyeonworks.com/public/build/1518.a3f1f690c084a37f01c7.js:362
[ 747139ms] [ERROR] WebSocket connection to 'wss://app2.hyeonworks.com/api/live/ws' failed: Error during WebSocket handshake: Unexpected response code: 400 @ https://app2.hyeonworks.com/public/build/1518.a3f1f690c084a37f01c7.js:362
[ 754565ms] [ERROR] WebSocket connection to 'wss://app2.hyeonworks.com/api/live/ws' failed: Error during WebSocket handshake: Unexpected response code: 400 @ https://app2.hyeonworks.com/public/build/1518.a3f1f690c084a37f01c7.js:362
[ 773682ms] [ERROR] WebSocket connection to 'wss://app2.hyeonworks.com/api/live/ws' failed: Error during WebSocket handshake: Unexpected response code: 400 @ https://app2.hyeonworks.com/public/build/1518.a3f1f690c084a37f01c7.js:362
[ 784674ms] [ERROR] WebSocket connection to 'wss://app2.hyeonworks.com/api/live/ws' failed: Error during WebSocket handshake: Unexpected response code: 400 @ https://app2.hyeonworks.com/public/build/1518.a3f1f690c084a37f01c7.js:362
[ 787399ms] [ERROR] WebSocket connection to 'wss://app2.hyeonworks.com/api/live/ws' failed: Error during WebSocket handshake: Unexpected response code: 400 @ https://app2.hyeonworks.com/public/build/1518.a3f1f690c084a37f01c7.js:362
[ 802845ms] [ERROR] WebSocket connection to 'wss://app2.hyeonworks.com/api/live/ws' failed: Error during WebSocket handshake: Unexpected response code: 400 @ https://app2.hyeonworks.com/public/build/1518.a3f1f690c084a37f01c7.js:362
[ 825589ms] [ERROR] WebSocket connection to 'wss://app2.hyeonworks.com/api/live/ws' failed: Error during WebSocket handshake: Unexpected response code: 400 @ https://app2.hyeonworks.com/public/build/1518.a3f1f690c084a37f01c7.js:362
[ 832768ms] [ERROR] WebSocket connection to 'wss://app2.hyeonworks.com/api/live/ws' failed: Error during WebSocket handshake: Unexpected response code: 400 @ https://app2.hyeonworks.com/public/build/1518.a3f1f690c084a37f01c7.js:362
[ 842043ms] [ERROR] WebSocket connection to 'wss://app2.hyeonworks.com/api/live/ws' failed: Error during WebSocket handshake: Unexpected response code: 400 @ https://app2.hyeonworks.com/public/build/1518.a3f1f690c084a37f01c7.js:362
[ 852717ms] [ERROR] WebSocket connection to 'wss://app2.hyeonworks.com/api/live/ws' failed: Error during WebSocket handshake: Unexpected response code: 400 @ https://app2.hyeonworks.com/public/build/1518.a3f1f690c084a37f01c7.js:362
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[ 876571ms] [ERROR] WebSocket connection to 'wss://app2.hyeonworks.com/api/live/ws' failed: Error during WebSocket handshake: Unexpected response code: 400 @ https://app2.hyeonworks.com/public/build/1518.a3f1f690c084a37f01c7.js:362
[ 894491ms] [ERROR] WebSocket connection to 'wss://app2.hyeonworks.com/api/live/ws' failed: Error during WebSocket handshake: Unexpected response code: 400 @ https://app2.hyeonworks.com/public/build/1518.a3f1f690c084a37f01c7.js:362
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[ 934752ms] [ERROR] WebSocket connection to 'wss://app2.hyeonworks.com/api/live/ws' failed: Error during WebSocket handshake: Unexpected response code: 400 @ https://app2.hyeonworks.com/public/build/1518.a3f1f690c084a37f01c7.js:362
[ 941175ms] [ERROR] WebSocket connection to 'wss://app2.hyeonworks.com/api/live/ws' failed: Error during WebSocket handshake: Unexpected response code: 400 @ https://app2.hyeonworks.com/public/build/1518.a3f1f690c084a37f01c7.js:362
[ 946004ms] [ERROR] WebSocket connection to 'wss://app2.hyeonworks.com/api/live/ws' failed: Error during WebSocket handshake: Unexpected response code: 400 @ https://app2.hyeonworks.com/public/build/1518.a3f1f690c084a37f01c7.js:362
[ 960849ms] [ERROR] WebSocket connection to 'wss://app2.hyeonworks.com/api/live/ws' failed: Error during WebSocket handshake: Unexpected response code: 400 @ https://app2.hyeonworks.com/public/build/1518.a3f1f690c084a37f01c7.js:362
[ 962180ms] [ERROR] WebSocket connection to 'wss://app2.hyeonworks.com/api/live/ws' failed: Error during WebSocket handshake: Unexpected response code: 400 @ https://app2.hyeonworks.com/public/build/1518.a3f1f690c084a37f01c7.js:362
[ 984446ms] [ERROR] WebSocket connection to 'wss://app2.hyeonworks.com/api/live/ws' failed: Error during WebSocket handshake: Unexpected response code: 400 @ https://app2.hyeonworks.com/public/build/1518.a3f1f690c084a37f01c7.js:362
[ 997579ms] [ERROR] WebSocket connection to 'wss://app2.hyeonworks.com/api/live/ws' failed: Error during WebSocket handshake: Unexpected response code: 400 @ https://app2.hyeonworks.com/public/build/1518.a3f1f690c084a37f01c7.js:362
[ 1010105ms] [ERROR] WebSocket connection to 'wss://app2.hyeonworks.com/api/live/ws' failed: Error during WebSocket handshake: Unexpected response code: 400 @ https://app2.hyeonworks.com/public/build/1518.a3f1f690c084a37f01c7.js:362
[ 1027190ms] [ERROR] WebSocket connection to 'wss://app2.hyeonworks.com/api/live/ws' failed: Error during WebSocket handshake: Unexpected response code: 400 @ https://app2.hyeonworks.com/public/build/1518.a3f1f690c084a37f01c7.js:362
[ 1043388ms] [ERROR] WebSocket connection to 'wss://app2.hyeonworks.com/api/live/ws' failed: Error during WebSocket handshake: Unexpected response code: 400 @ https://app2.hyeonworks.com/public/build/1518.a3f1f690c084a37f01c7.js:362
[ 1061311ms] [ERROR] WebSocket connection to 'wss://app2.hyeonworks.com/api/live/ws' failed: Error during WebSocket handshake: Unexpected response code: 400 @ https://app2.hyeonworks.com/public/build/1518.a3f1f690c084a37f01c7.js:362
[ 1066040ms] [ERROR] WebSocket connection to 'wss://app2.hyeonworks.com/api/live/ws' failed: Error during WebSocket handshake: Unexpected response code: 400 @ https://app2.hyeonworks.com/public/build/1518.a3f1f690c084a37f01c7.js:362
[ 1080349ms] [ERROR] WebSocket connection to 'wss://app2.hyeonworks.com/api/live/ws' failed: Error during WebSocket handshake: Unexpected response code: 400 @ https://app2.hyeonworks.com/public/build/1518.a3f1f690c084a37f01c7.js:362
[ 1092336ms] [ERROR] WebSocket connection to 'wss://app2.hyeonworks.com/api/live/ws' failed: Error during WebSocket handshake: Unexpected response code: 400 @ https://app2.hyeonworks.com/public/build/1518.a3f1f690c084a37f01c7.js:362
[ 1104312ms] [ERROR] WebSocket connection to 'wss://app2.hyeonworks.com/api/live/ws' failed: Error during WebSocket handshake: Unexpected response code: 400 @ https://app2.hyeonworks.com/public/build/1518.a3f1f690c084a37f01c7.js:362
[ 1109362ms] [ERROR] WebSocket connection to 'wss://app2.hyeonworks.com/api/live/ws' failed: Error during WebSocket handshake: Unexpected response code: 400 @ https://app2.hyeonworks.com/public/build/1518.a3f1f690c084a37f01c7.js:362
[ 1127047ms] [ERROR] WebSocket connection to 'wss://app2.hyeonworks.com/api/live/ws' failed: Error during WebSocket handshake: Unexpected response code: 400 @ https://app2.hyeonworks.com/public/build/1518.a3f1f690c084a37f01c7.js:362
[ 1134728ms] [ERROR] WebSocket connection to 'wss://app2.hyeonworks.com/api/live/ws' failed: Error during WebSocket handshake: Unexpected response code: 400 @ https://app2.hyeonworks.com/public/build/1518.a3f1f690c084a37f01c7.js:362
[ 1154899ms] [ERROR] WebSocket connection to 'wss://app2.hyeonworks.com/api/live/ws' failed: Error during WebSocket handshake: Unexpected response code: 400 @ https://app2.hyeonworks.com/public/build/1518.a3f1f690c084a37f01c7.js:362
[ 1161253ms] [ERROR] WebSocket connection to 'wss://app2.hyeonworks.com/api/live/ws' failed: Error during WebSocket handshake: Unexpected response code: 400 @ https://app2.hyeonworks.com/public/build/1518.a3f1f690c084a37f01c7.js:362
[ 1174971ms] [ERROR] WebSocket connection to 'wss://app2.hyeonworks.com/api/live/ws' failed: Error during WebSocket handshake: Unexpected response code: 400 @ https://app2.hyeonworks.com/public/build/1518.a3f1f690c084a37f01c7.js:362
[ 1184491ms] [ERROR] WebSocket connection to 'wss://app2.hyeonworks.com/api/live/ws' failed: Error during WebSocket handshake: Unexpected response code: 400 @ https://app2.hyeonworks.com/public/build/1518.a3f1f690c084a37f01c7.js:362
[ 1185340ms] [ERROR] WebSocket connection to 'wss://app2.hyeonworks.com/api/live/ws' failed: Error during WebSocket handshake: Unexpected response code: 400 @ https://app2.hyeonworks.com/public/build/1518.a3f1f690c084a37f01c7.js:362
[ 1189111ms] [ERROR] WebSocket connection to 'wss://app2.hyeonworks.com/api/live/ws' failed: Error during WebSocket handshake: Unexpected response code: 400 @ https://app2.hyeonworks.com/public/build/1518.a3f1f690c084a37f01c7.js:362
[ 1196984ms] [ERROR] WebSocket connection to 'wss://app2.hyeonworks.com/api/live/ws' failed: Error during WebSocket handshake: Unexpected response code: 400 @ https://app2.hyeonworks.com/public/build/1518.a3f1f690c084a37f01c7.js:362
[ 1204794ms] [ERROR] WebSocket connection to 'wss://app2.hyeonworks.com/api/live/ws' failed: Error during WebSocket handshake: Unexpected response code: 400 @ https://app2.hyeonworks.com/public/build/1518.a3f1f690c084a37f01c7.js:362
[ 1247961ms] [WARNING] WebSocket connection to 'wss://app2.hyeonworks.com/api/live/ws' failed: WebSocket is closed before the connection is established. @ https://app2.hyeonworks.com/public/build/1518.a3f1f690c084a37f01c7.js:362
[ 1286322ms] [WARNING] WebSocket connection to 'wss://app2.hyeonworks.com/api/live/ws' failed: WebSocket is closed before the connection is established. @ https://app2.hyeonworks.com/public/build/1518.a3f1f690c084a37f01c7.js:362
[ 1319329ms] [WARNING] WebSocket connection to 'wss://app2.hyeonworks.com/api/live/ws' failed: WebSocket is closed before the connection is established. @ https://app2.hyeonworks.com/public/build/1518.a3f1f690c084a37f01c7.js:362
[ 1362771ms] [WARNING] WebSocket connection to 'wss://app2.hyeonworks.com/api/live/ws' failed: WebSocket is closed before the connection is established. @ https://app2.hyeonworks.com/public/build/1518.a3f1f690c084a37f01c7.js:362
[ 1396881ms] [WARNING] WebSocket connection to 'wss://app2.hyeonworks.com/api/live/ws' failed: WebSocket is closed before the connection is established. @ https://app2.hyeonworks.com/public/build/1518.a3f1f690c084a37f01c7.js:362
[ 1434184ms] [ERROR] Failed to load resource: the server responded with a status of 502 () @ https://app2.hyeonworks.com/api/user/auth-tokens/rotate:0
[ 1443506ms] [WARNING] WebSocket connection to 'wss://app2.hyeonworks.com/api/live/ws' failed: WebSocket is closed before the connection is established. @ https://app2.hyeonworks.com/public/build/1518.a3f1f690c084a37f01c7.js:362
[ 1465016ms] [ERROR] WebSocket connection to 'wss://app2.hyeonworks.com/api/live/ws' failed: Error during WebSocket handshake: Unexpected response code: 502 @ https://app2.hyeonworks.com/public/build/1518.a3f1f690c084a37f01c7.js:362
[ 1513337ms] [WARNING] WebSocket connection to 'wss://app2.hyeonworks.com/api/live/ws' failed: WebSocket is closed before the connection is established. @ https://app2.hyeonworks.com/public/build/1518.a3f1f690c084a37f01c7.js:362
[ 1556906ms] [WARNING] WebSocket connection to 'wss://app2.hyeonworks.com/api/live/ws' failed: WebSocket is closed before the connection is established. @ https://app2.hyeonworks.com/public/build/1518.a3f1f690c084a37f01c7.js:362
[ 1562963ms] [ERROR] WebSocket connection to 'wss://app2.hyeonworks.com/api/live/ws' failed: Error during WebSocket handshake: Unexpected response code: 502 @ https://app2.hyeonworks.com/public/build/1518.a3f1f690c084a37f01c7.js:362
[ 1572896ms] [ERROR] WebSocket connection to 'wss://app2.hyeonworks.com/api/live/ws' failed: Error during WebSocket handshake: Unexpected response code: 502 @ https://app2.hyeonworks.com/public/build/1518.a3f1f690c084a37f01c7.js:362
[ 1576390ms] [ERROR] WebSocket connection to 'wss://app2.hyeonworks.com/api/live/ws' failed: Error during WebSocket handshake: Unexpected response code: 503 @ https://app2.hyeonworks.com/public/build/1518.a3f1f690c084a37f01c7.js:362
[ 1593794ms] [ERROR] WebSocket connection to 'wss://app2.hyeonworks.com/api/live/ws' failed: HTTP Authentication failed; no valid credentials available @ https://app2.hyeonworks.com/public/build/1518.a3f1f690c084a37f01c7.js:362
[ 1600651ms] [ERROR] WebSocket connection to 'wss://app2.hyeonworks.com/api/live/ws' failed: HTTP Authentication failed; no valid credentials available @ https://app2.hyeonworks.com/public/build/1518.a3f1f690c084a37f01c7.js:362
[ 1616424ms] [ERROR] WebSocket connection to 'wss://app2.hyeonworks.com/api/live/ws' failed: HTTP Authentication failed; no valid credentials available @ https://app2.hyeonworks.com/public/build/1518.a3f1f690c084a37f01c7.js:362
@@ -0,0 +1,20 @@
[ 268ms] [WARNING] <meta name="apple-mobile-web-app-capable" content="yes"> is deprecated. Please include <meta name="mobile-web-app-capable" content="yes"> @ https://app2.hyeonworks.com/login:0
[ 379ms] [VERBOSE] [DOM] Input elements should have autocomplete attributes (suggested: "username"): (More info: https://goo.gl/9p2vKq) %o @ https://app2.hyeonworks.com/login:0
[ 10453ms] [ERROR] WebSocket connection to 'wss://app2.hyeonworks.com/api/live/ws' failed: Error during WebSocket handshake: Unexpected response code: 400 @ https://app2.hyeonworks.com/public/build/1518.a3f1f690c084a37f01c7.js:362
[ 10532ms] [WARNING] <meta name="apple-mobile-web-app-capable" content="yes"> is deprecated. Please include <meta name="mobile-web-app-capable" content="yes"> @ https://app2.hyeonworks.com/explore?schemaVersion=1&panes=%7B%22ich%22%3A%7B%22datasource%22%3A%22PBFA97CFB590B2093%22%2C%22queries%22%3A%5B%7B%22refId%22%3A%22A%22%2C%22expr%22%3A%22up%7Bjob%3D%7E%5C%22keycloak%7Cnode-exporter%5C%22%7D%22%2C%22range%22%3Atrue%2C%22instant%22%3Afalse%2C%22editorMode%22%3A%22code%22%2C%22legendFormat%22%3A%22%7B%7Bjob%7D%7D+%E2%80%94+%7B%7Bpod%7D%7D%7B%7Bnode%7D%7D%22%2C%22datasource%22%3A%7B%22type%22%3A%22prometheus%22%2C%22uid%22%3A%22PBFA97CFB590B2093%22%7D%7D%5D%2C%22range%22%3A%7B%22from%22%3A%22now-55m%22%2C%22to%22%3A%22now%22%7D%7D%7D&orgId=1:0
[ 11687ms] [ERROR] WebSocket connection to 'wss://app2.hyeonworks.com/api/live/ws' failed: Error during WebSocket handshake: Unexpected response code: 400 @ https://app2.hyeonworks.com/public/build/1518.a3f1f690c084a37f01c7.js:362
[ 13737ms] [ERROR] WebSocket connection to 'wss://app2.hyeonworks.com/api/live/ws' failed: Error during WebSocket handshake: Unexpected response code: 400 @ https://app2.hyeonworks.com/public/build/1518.a3f1f690c084a37f01c7.js:362
[ 15113ms] [ERROR] WebSocket connection to 'wss://app2.hyeonworks.com/api/live/ws' failed: Error during WebSocket handshake: Unexpected response code: 400 @ https://app2.hyeonworks.com/public/build/1518.a3f1f690c084a37f01c7.js:362
[ 20185ms] [ERROR] WebSocket connection to 'wss://app2.hyeonworks.com/api/live/ws' failed: Error during WebSocket handshake: Unexpected response code: 400 @ https://app2.hyeonworks.com/public/build/1518.a3f1f690c084a37f01c7.js:362
[ 27259ms] [ERROR] WebSocket connection to 'wss://app2.hyeonworks.com/api/live/ws' failed: Error during WebSocket handshake: Unexpected response code: 400 @ https://app2.hyeonworks.com/public/build/1518.a3f1f690c084a37f01c7.js:362
[ 40154ms] [ERROR] WebSocket connection to 'wss://app2.hyeonworks.com/api/live/ws' failed: Error during WebSocket handshake: Unexpected response code: 400 @ https://app2.hyeonworks.com/public/build/1518.a3f1f690c084a37f01c7.js:362
[ 41870ms] [ERROR] WebSocket connection to 'wss://app2.hyeonworks.com/api/live/ws' failed: Error during WebSocket handshake: Unexpected response code: 400 @ https://app2.hyeonworks.com/public/build/1518.a3f1f690c084a37f01c7.js:362
[ 50493ms] [ERROR] WebSocket connection to 'wss://app2.hyeonworks.com/api/live/ws' failed: Error during WebSocket handshake: Unexpected response code: 400 @ https://app2.hyeonworks.com/public/build/1518.a3f1f690c084a37f01c7.js:362
[ 54082ms] [ERROR] WebSocket connection to 'wss://app2.hyeonworks.com/api/live/ws' failed: Error during WebSocket handshake: Unexpected response code: 400 @ https://app2.hyeonworks.com/public/build/1518.a3f1f690c084a37f01c7.js:362
[ 60121ms] [ERROR] WebSocket connection to 'wss://app2.hyeonworks.com/api/live/ws' failed: Error during WebSocket handshake: Unexpected response code: 400 @ https://app2.hyeonworks.com/public/build/1518.a3f1f690c084a37f01c7.js:362
[ 74362ms] [ERROR] WebSocket connection to 'wss://app2.hyeonworks.com/api/live/ws' failed: Error during WebSocket handshake: Unexpected response code: 400 @ https://app2.hyeonworks.com/public/build/1518.a3f1f690c084a37f01c7.js:362
[ 83269ms] [ERROR] WebSocket connection to 'wss://app2.hyeonworks.com/api/live/ws' failed: Error during WebSocket handshake: Unexpected response code: 400 @ https://app2.hyeonworks.com/public/build/1518.a3f1f690c084a37f01c7.js:362
[ 95349ms] [ERROR] WebSocket connection to 'wss://app2.hyeonworks.com/api/live/ws' failed: Error during WebSocket handshake: Unexpected response code: 400 @ https://app2.hyeonworks.com/public/build/1518.a3f1f690c084a37f01c7.js:362
[ 98008ms] [ERROR] WebSocket connection to 'wss://app2.hyeonworks.com/api/live/ws' failed: Error during WebSocket handshake: Unexpected response code: 400 @ https://app2.hyeonworks.com/public/build/1518.a3f1f690c084a37f01c7.js:362
[ 104458ms] [ERROR] WebSocket connection to 'wss://app2.hyeonworks.com/api/live/ws' failed: Error during WebSocket handshake: Unexpected response code: 400 @ https://app2.hyeonworks.com/public/build/1518.a3f1f690c084a37f01c7.js:362
[ 123816ms] [ERROR] WebSocket connection to 'wss://app2.hyeonworks.com/api/live/ws' failed: Error during WebSocket handshake: Unexpected response code: 400 @ https://app2.hyeonworks.com/public/build/1518.a3f1f690c084a37f01c7.js:362
@@ -0,0 +1,44 @@
- main [ref=f6e7]:
- generic [ref=f6e9]:
- generic [ref=f6e11]:
- generic [ref=f6e12]:
- img "Grafana" [ref=f6e13]
- heading "Welcome to Grafana" [level=1] [ref=f6e15]
- generic [ref=f6e19]:
- generic [ref=f6e20]:
- generic [ref=f6e21]: Email or username
- textbox "Email or username" [active] [ref=f6e28]:
- /placeholder: email or username
- generic [ref=f6e29]:
- generic [ref=f6e30]: Password
- generic [ref=f6e36]:
- textbox "Password" [ref=f6e37]:
- /placeholder: password
- switch "Show password" [ref=f6e39] [cursor=pointer]
- button "Log in" [ref=f6e42] [cursor=pointer]
- link "Forgot your password?" [ref=f6e45] [cursor=pointer]:
- /url: /user/password/send-reset-email
- list [ref=f6e49]:
- listitem [ref=f6e50]:
- link "Documentation" [ref=f6e53] [cursor=pointer]:
- /url: https://grafana.com/docs/grafana/latest/?utm_source=grafana_footer
- text: "|"
- listitem [ref=f6e54]:
- link "Support" [ref=f6e57] [cursor=pointer]:
- /url: https://grafana.com/products/enterprise/?utm_source=grafana_footer
- text: "|"
- listitem [ref=f6e58]:
- link "Community" [ref=f6e61] [cursor=pointer]:
- /url: https://community.grafana.com/?utm_source=grafana_footer
- text: "|"
- listitem [ref=f6e62]:
- link "Open Source" [ref=f6e63] [cursor=pointer]:
- /url: https://grafana.com/oss/grafana?utm_source=grafana_footer
- text: "|"
- listitem [ref=f6e64]:
- link "Grafana v11.4.0 (b58701869e)" [ref=f6e65] [cursor=pointer]:
- /url: https://github.com/grafana/grafana/blob/main/CHANGELOG.md
- text: "|"
- listitem [ref=f6e66]:
- link "New version available!" [ref=f6e69] [cursor=pointer]:
- /url: https://grafana.com/grafana/download?utm_source=grafana_footer
@@ -0,0 +1,159 @@
- generic [active] [ref=f9e1]:
- generic [ref=f9e4]:
- link "Skip to main content" [ref=f9e5] [cursor=pointer]:
- /url: "#pageContent"
- banner [ref=f9e7]:
- generic [ref=f9e8]:
- link [ref=f9e10] [cursor=pointer]:
- /url: /
- img "Grafana" [ref=f9e11]
- generic [ref=f9e14]:
- button "Search or jump to..." [ref=f9e18] [cursor=pointer]
- generic [ref=f9e19]: ctrl+k
- generic [ref=f9e23]:
- button "New" [ref=f9e24] [cursor=pointer]
- button "Help" [ref=f9e30] [cursor=pointer]
- button "News" [ref=f9e33] [cursor=pointer]
- button "Profile" [ref=f9e36] [cursor=pointer]:
- img "User avatar" [ref=f9e37]
- generic [ref=f9e38]:
- button "Open menu" [ref=f9e40] [cursor=pointer]
- navigation "Breadcrumbs" [ref=f9e43]:
- list [ref=f9e44]:
- listitem [ref=f9e45]:
- link "Home" [ref=f9e46] [cursor=pointer]:
- /url: /
- listitem [ref=f9e50]:
- link "Explore" [ref=f9e51] [cursor=pointer]:
- /url: /explore
- listitem [ref=f9e55]:
- generic "Prometheus" [ref=f9e56]
- generic [ref=f9e57]:
- generic [ref=f9e60]:
- button "Copy shortened URL" [ref=f9e61] [cursor=pointer]
- button "Open copy link options" [ref=f9e64] [cursor=pointer]
- button "Toggle top search bar" [ref=f9e68] [cursor=pointer]
- main [ref=f9e74]:
- generic [ref=f9e76]:
- heading "Explore" [level=1] [ref=f9e77]
- generic [ref=f9e82]:
- navigation "Explore toolbar" [ref=f9e84]:
- navigation "Search links" [ref=f9e86]:
- generic [ref=f9e87]:
- button "Content outline" [expanded] [ref=f9e89] [cursor=pointer]:
- generic [ref=f9e92]: Outline
- generic [ref=f9e97] [cursor=pointer]:
- img "Prometheus logo" [ref=f9e99]
- textbox "Select a data source" [ref=f9e100]:
- /placeholder: ""
- generic [ref=f9e104]:
- button "Split the pane" [ref=f9e106] [cursor=pointer]:
- generic [ref=f9e109]: Split
- button "Add" [ref=f9e111] [cursor=pointer]
- generic [ref=f9e116]:
- 'button "Time range selected: Last 55 minutes" [ref=f9e117] [cursor=pointer]'
- button "Zoom out time range" [ref=f9e122] [cursor=pointer]
- generic [ref=f9e126]:
- button "Run query" [ref=f9e127] [cursor=pointer]
- button "Auto refresh turned off. Choose refresh time interval" [ref=f9e131] [cursor=pointer]
- generic [ref=f9e135]:
- generic [ref=f9e139]:
- button "Collapse outline" [expanded] [ref=f9e141] [cursor=pointer]:
- img "arrow-from-right" [ref=f9e142]
- button "Queries" [ref=f9e145] [cursor=pointer]:
- img "arrow" [ref=f9e146]
- button "Graph" [ref=f9e150] [cursor=pointer]:
- img "graph-bar" [ref=f9e151]
- generic [ref=f9e158]:
- generic [ref=f9e160]:
- generic "Query editor row" [ref=f9e163]:
- generic [ref=f9e164]:
- generic [ref=f9e166]:
- generic [ref=f9e167]:
- button "Collapse query row" [expanded] [ref=f9e168] [cursor=pointer]
- generic [ref=f9e171]:
- button "Query editor row title A" [ref=f9e172] [cursor=pointer]:
- generic [ref=f9e173]: A
- emphasis [ref=f9e174]: (Prometheus)
- generic [ref=f9e175]:
- button "Show data source help" [ref=f9e177] [cursor=pointer]
- button "Duplicate query" [ref=f9e181] [cursor=pointer]
- button "Hide response" [ref=f9e185] [cursor=pointer]
- button "Remove query" [ref=f9e189] [cursor=pointer]
- button "Drag and drop to reorder" [ref=f9e192]:
- img "Drag and drop to reorder" [ref=f9e193]
- generic [ref=f9e196]:
- generic [ref=f9e197]:
- button "Kick start your query" [ref=f9e198] [cursor=pointer]
- generic [ref=f9e201]:
- generic [ref=f9e202] [cursor=pointer]: Explain
- generic [ref=f9e203]:
- checkbox "Explain Toggle switch" [ref=f9e204]
- generic "Toggle switch" [ref=f9e205] [cursor=pointer]
- radiogroup [ref=f9e210]:
- generic [ref=f9e211]:
- radio "Builder" [ref=f9e212] [cursor=pointer]
- generic [ref=f9e213] [cursor=pointer]: Builder
- generic [ref=f9e214]:
- radio "Code" [checked] [ref=f9e215] [cursor=pointer]
- generic [ref=f9e216] [cursor=pointer]: Code
- generic [ref=f9e218]:
- generic [ref=f9e220]:
- button "Metrics browser" [ref=f9e221] [cursor=pointer]
- code [ref=f9e228]:
- generic [ref=f9e229]:
- generic [ref=f9e234]: "up{job=~\"keycloak|node-exporter\"}"
- textbox "Editor content;Press Alt+F1 for Accessibility Options." [ref=f9e239]: "up{job=~\"keycloak|node-exporter\"}"
- 'button "Options Legend: {{job}} — {{pod}}{{node}} Format: Time series Step: auto Type: Range Exemplars: false" [ref=f9e245] [cursor=pointer]':
- generic [ref=f9e249]:
- heading "Options" [level=6] [ref=f9e250]
- generic [ref=f9e251]:
- generic [ref=f9e252]: "Legend: {{job}} — {{pod}}{{node}}"
- generic [ref=f9e253]: "Format: Time series"
- generic [ref=f9e254]: "Step: auto"
- generic [ref=f9e255]: "Type: Range"
- generic [ref=f9e256]: "Exemplars: false"
- generic [ref=f9e257]:
- button "Add query" [ref=f9e258] [cursor=pointer]
- button "Query history" [ref=f9e262] [cursor=pointer]
- button "Query inspector" [ref=f9e266] [cursor=pointer]
- main [ref=f9e270]:
- region [ref=f9e272]:
- generic [ref=f9e273]:
- heading "Graph" [level=2] [ref=f9e275]
- radiogroup [ref=f9e278]:
- generic [ref=f9e279]:
- radio "Lines" [checked] [ref=f9e280] [cursor=pointer]
- generic [ref=f9e281] [cursor=pointer]: Lines
- generic [ref=f9e282]:
- radio "Bars" [ref=f9e283] [cursor=pointer]
- generic [ref=f9e284] [cursor=pointer]: Bars
- generic [ref=f9e285]:
- radio "Points" [ref=f9e286] [cursor=pointer]
- generic [ref=f9e287] [cursor=pointer]: Points
- generic [ref=f9e288]:
- radio "Stacked lines" [ref=f9e289] [cursor=pointer]
- generic [ref=f9e290] [cursor=pointer]: Stacked lines
- generic [ref=f9e291]:
- radio "Stacked bars" [ref=f9e292] [cursor=pointer]
- generic [ref=f9e293] [cursor=pointer]: Stacked bars
- list [ref=f9e311]:
- listitem [ref=f9e312]:
- button "keycloak — keycloak-1kc-lab-1" [ref=f9e316] [cursor=pointer]
- listitem [ref=f9e317]:
- button "keycloak — keycloak-1kc-lab-1" [ref=f9e321] [cursor=pointer]
- listitem [ref=f9e322]:
- button "keycloak — keycloak-0kc-lab-2" [ref=f9e326] [cursor=pointer]
- listitem [ref=f9e327]:
- button "keycloak — keycloak-0kc-lab-2" [ref=f9e331] [cursor=pointer]
- listitem [ref=f9e332]:
- button "keycloak — keycloak-0kc-lab-2" [ref=f9e336] [cursor=pointer]
- listitem [ref=f9e337]:
- button "node-exporter — kc-lab-1" [ref=f9e341] [cursor=pointer]
- listitem [ref=f9e342]:
- button "node-exporter — kc-lab-2" [ref=f9e346] [cursor=pointer]
- generic [ref=f9e351]:
- alert
- alert
- complementary
- complementary
@@ -0,0 +1,20 @@
=== A-4 기준선 ===
kc-lab-1 Ready true
kc-lab-2 Ready <none>
a2-probe true kc-lab-2
keycloak-0 true kc-lab-2
keycloak-1 true kc-lab-1
postgres-7b474b88c8-2gf27 true kc-lab-2
=== PVC 가 어느 노드에 묶여 있는가 (재배치 가능성) ===
persistentvolumeclaim/postgres-data → kc-lab-2
=== 서비스 정상 확인 ===
https://auth.hyeonworks.com/realms/master HTTP 200
=== VM 상태 ===
--------------------------
1 kc-lab-1 running
2 kc-lab-2 running
@@ -0,0 +1,17 @@
=== 워커 노드(kc-lab-2) 전원 차단 — virsh destroy 는 종료 신호가 없다 ===
차단 시각: 12:07:43
Domain 'kc-lab-2' destroyed
+15초 node=Ready | keycloak-0=Running postgres-7b474b88c8-2gf27=Running | 외부 HTTP 000
+30초 node=Ready | keycloak-0=Running postgres-7b474b88c8-2gf27=Running | 외부 HTTP 000
+45초 node=NotReady | keycloak-0=Running postgres-7b474b88c8-2gf27=Running | 외부 HTTP 503
+60초 node=NotReady | keycloak-0=Running postgres-7b474b88c8-2gf27=Running | 외부 HTTP 503
+75초 node=NotReady | keycloak-0=Running postgres-7b474b88c8-2gf27=Running | 외부 HTTP 503
+90초 node=NotReady | keycloak-0=Running postgres-7b474b88c8-2gf27=Running | 외부 HTTP 503
+105초 node=NotReady | keycloak-0=Running postgres-7b474b88c8-2gf27=Running | 외부 HTTP 503
+120초 node=NotReady | keycloak-0=Running postgres-7b474b88c8-2gf27=Running | 외부 HTTP 503
+135초 node=NotReady | keycloak-0=Running postgres-7b474b88c8-2gf27=Running | 외부 HTTP 503
+150초 node=NotReady | keycloak-0=Running postgres-7b474b88c8-2gf27=Running | 외부 HTTP 503
+165초 node=NotReady | keycloak-0=Running postgres-7b474b88c8-2gf27=Running | 외부 HTTP 503
+180초 node=NotReady | keycloak-0=Running postgres-7b474b88c8-2gf27=Running | 외부 HTTP 503
@@ -0,0 +1,28 @@
=== 파드 상태의 진실 — Running 인데 노드가 없다 ===
a2-probe Running true kc-lab-2 <none>
keycloak-0 Running true kc-lab-2 <none>
keycloak-1 Running false kc-lab-1 <none>
postgres-7b474b88c8-2gf27 Running true kc-lab-2 <none>
=== 재배치가 시도되었는가 ===
10m Warning Unhealthy pod/keycloak-0 Readiness probe failed: Get "http://10.42.1.67:9000/health/ready": context deadline exceeded (Client.Timeout exceeded while awaiting headers)
3m15s Warning NodeNotReady pod/postgres-7b474b88c8-2gf27 Node is not ready
3m15s Warning NodeNotReady pod/keycloak-0 Node is not ready
3m15s Warning NodeNotReady pod/a2-probe Node is not ready
2m27s Warning Unhealthy pod/keycloak-1 Readiness probe failed: Get "http://10.42.0.35:9000/health/ready": context deadline exceeded (Client.Timeout exceeded while awaiting headers)
2s Warning Unhealthy pod/keycloak-1 Readiness probe failed: HTTP probe failed with statuscode: 503
=== 노드 taint — 쿠버네티스가 붙인 것 ===
node.kubernetes.io/unreachable=:NoSchedule
node.kubernetes.io/unreachable=:NoExecute
=== Prometheus 가 본 것 (kc-lab-1 에 있어 살아남았다) ===
up{job=keycloak pod=keycloak-1 } = 1
up{job=keycloak pod=keycloak-0 } = 0
up{job=kubelet pod=- } = 1
up{job=kubelet pod=- } = 0
up{job=node-exporter pod=kc-lab-1 } = 1
up{job=node-exporter pod=kc-lab-2 } = 0
up{job=prometheus pod=- } = 1
=== 진입점이 처음 40초간 000 이었던 이유 — nginx upstream ===
@@ -0,0 +1,15 @@
=== nginx 설정 위치 찾기 ===
=== NoExecute taint 의 tolerationSeconds — 언제 축출되는가 ===
node.kubernetes.io/not-ready NoExecute tolerationSeconds=300
node.kubernetes.io/unreachable NoExecute tolerationSeconds=300
=== 5분 축출 시점까지 관찰 ===
+210초 a2-probe:Running keycloak-0:Running keycloak-1:Running postgres-7b474b88c8-2gf27:Running
+240초 a2-probe:Running keycloak-0:Running keycloak-1:Running postgres-7b474b88c8-2gf27:Running
+270초 a2-probe:Terminating keycloak-0:Terminating keycloak-1:Running postgres-7b474b88c8-2gf27:Terminating postgres-7b474b88c8-9cmsv:Pending
+300초 a2-probe:Terminating keycloak-0:Terminating keycloak-1:Running postgres-7b474b88c8-2gf27:Terminating postgres-7b474b88c8-9cmsv:Pending
+330초 a2-probe:Terminating keycloak-0:Terminating keycloak-1:Running postgres-7b474b88c8-2gf27:Terminating postgres-7b474b88c8-9cmsv:Pending
+360초 a2-probe:Terminating keycloak-0:Terminating keycloak-1:Running postgres-7b474b88c8-2gf27:Terminating postgres-7b474b88c8-9cmsv:Pending
+390초 a2-probe:Terminating keycloak-0:Terminating keycloak-1:Running postgres-7b474b88c8-2gf27:Terminating postgres-7b474b88c8-9cmsv:Pending
+420초 a2-probe:Terminating keycloak-0:Terminating keycloak-1:Running postgres-7b474b88c8-2gf27:Terminating postgres-7b474b88c8-9cmsv:Pending
@@ -0,0 +1,18 @@
=== 새 postgres 가 Pending 인 이유 ===
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Warning FailedScheduling 4m45s default-scheduler 0/2 nodes are available: 1 node(s) didn't match PersistentVolume's node affinity, 1 node(s) had untolerated taint(s). no new claims to deallocate, preemption: 0/2 nodes are available: 2 Preemption is not helpful for scheduling.
=== keycloak-0 대체 파드가 안 생기는 이유 (StatefulSet) ===
keycloak 2 <none> 1
keycloak-0 1/1 Terminating 0 30m
keycloak-1 0/1 Running 0 143m
=== 복구 — 노드 재기동 ===
재기동 시각: 12:16:31
Domain 'kc-lab-2' started
+30초 node=Ready | Running 파드 3 개 | 외부 HTTP 503
+60초 node=Ready | Running 파드 3 개 | 외부 HTTP 200
→ 서비스 복귀
@@ -0,0 +1,19 @@
=== 복구 확인 ===
keycloak-0 1/1 Running 0 68s
keycloak-1 1/1 Running 0 144m
postgres-7b474b88c8-9cmsv 1/1 Running 0 4m20s
=== kc-lab-1(k3s server)에 무엇이 있는가 — 이게 곧 영향 범위다 ===
keycloak-lab keycloak-1
kube-system coredns-54996dc9b4-8k8fj
kube-system helm-install-traefik-crd-q29b5
kube-system local-path-provisioner-77b9867795-g27z8
kube-system metrics-server-6dc596dfb8-7xxq4
kube-system svclb-traefik-5eb6a9a1-qwwk5
kube-system traefik-5d6fcf895-wpfhr
observability grafana-845b5678cf-b6gvc
observability node-exporter-9qk9w
observability prometheus-6774f94f7c-pzr2t
=== Traefik replica 수 (진입점의 단일 장애점인가) ===
traefik 1 1
@@ -0,0 +1,19 @@
=== 컨트롤 플레인 노드(kc-lab-1) 전원 차단 ===
차단 시각: 12:18:08
Domain 'kc-lab-1' destroyed
+20초 외부 auth=000 grafana=000 | kubectl: Unable to connect to the server: dial tcp
+40초 외부 auth=000 grafana=000 | kubectl: Unable to connect to the server: dial tcp
+60초 외부 auth=000 grafana=000 | kubectl: Unable to connect to the server: dial tcp
+80초 외부 auth=000 grafana=000 | kubectl: Unable to connect to the server: dial tcp
+100초 외부 auth=000 grafana=000 | kubectl: Unable to connect to the server: dial tcp
+120초 외부 auth=000 grafana=502 | kubectl: Unable to connect to the server: dial tcp
+140초 외부 auth=000 grafana=000 | kubectl: Unable to connect to the server: dial tcp
+160초 외부 auth=000 grafana=000 | kubectl: Unable to connect to the server: dial tcp
=== 살아 있는 노드에서 직접 확인 — 워크로드는 도는가 ===
CONTAINER IMAGE CREATED STATE NAME ATTEMPT POD ID POD NAMESPACE
e5f777900b762 60e153026e8f5 4 minutes ago Running keycloak 0 640d4dafaefb3 keycloak-0 keycloak-lab
6
@@ -0,0 +1,13 @@
=== 컨트롤 플레인 노드 복구 ===
재기동: 12:23:39
Domain 'kc-lab-1' started
+30초 외부=502 | kc-lab-1=Ready kc-lab-2=Ready
+60초 외부=200 | kc-lab-1=Ready kc-lab-2=Ready
→ 서비스 복귀 (총 60초)
=== 최종 상태 ===
keycloak-0 1/1 Running 0 7m57s
keycloak-1 1/1 Running 1 (<invalid> ago) 151m
postgres-7b474b88c8-9cmsv 1/1 Running 0 11m
(prometheus port-forward 재연결 필요)
+23
View File
@@ -0,0 +1,23 @@
# A-4 — 노드 전원 차단 증거
2026-09-04 12:0712:24 KST
해설: [`docs/experiment-a4-node-loss.md`](../../experiment-a4-node-loss.md)
| 파일 | 무엇을 보여주는가 |
|---|---|
| `01-baseline.txt` | 차단 전 — 양쪽 Ready, **PVC 가 kc-lab-2 에 못박혀 있음**(재배치 불가의 원인), 외부 200 |
| `02-worker-node-killed.txt` | `virsh destroy kc-lab-2`**40초간 노드가 Ready 로 남아 있고** 외부는 이미 `000`. 이후 `503` |
| `03-state-during-loss.txt` | **죽은 파드가 `ready=true`, 산 파드가 `ready=false`.** `up` 은 정확히 0. `unreachable` taint |
| `04-eviction-timing.txt` | `tolerationSeconds=300`**5분 뒤** 축출, 새 postgres 는 `Pending` |
| `05-recovery.txt` | `FailedScheduling: didn't match PersistentVolume's node affinity`, StatefulSet `DESIRED=2 CURRENT=1`. 노드 복귀 후 **60초** |
| `06-control-plane-inventory.txt` | kc-lab-1 에 있는 것 목록 — **Traefik `replicas=1`** |
| `07-control-plane-loss.txt` | `virsh destroy kc-lab-1` — 외부 `000`, `kubectl` 불통. **그런데 `crictl ps` 로 보면 keycloak-0 은 Running** |
| `08-control-plane-recovery.txt` | 60초 만에 복귀 |
| `a4-up-dropped-per-node.png` | Grafana — `up` 이 노드별로 0 으로 떨어지는 구간. 12:1812:23 은 **0 이 아니라 데이터 없음**(관측자가 같이 죽음) |
## 핵심 네 줄
1. **쿠버네티스는 40초 동안 노드가 살아 있다고 말한다.** 사용자는 이미 장애를 겪는 중이다.
2. **죽은 파드의 상태는 화석이다.** `ready=true` 인 파드가 꺼진 기계 위에 있다.
3. **StatefulSet 은 대체 파드를 만들지 않고, PVC 는 재배치를 막는다.** 사람이 개입해야 한다.
4. **컨트롤 플레인 상실 ≠ 워크로드 상실.** 컨테이너는 계속 돌고, 들어갈 문만 사라진다.
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# A-4 — 노드가 통째로 죽으면 어떻게 되는가
브랜치 `feature/keycloak-a4-node-loss` ·
증거 [`docs/evidence/a4-node-loss/`](evidence/a4-node-loss/) ·
2026-09-04 12:0712:24 KST
선행: [`A-2`](experiment-a2-database-loss.md) · [`A-3`](experiment-a3-database-crash.md)
**두 판본으로 나눠 실행했다.**
| | 죽인 노드 | 성격 |
|---|---|---|
| **4a** | `kc-lab-2` (워커) | Keycloak + **DB 동시 상실** |
| **4b** | `kc-lab-1` (k3s 서버) | **컨트롤 플레인 + 진입점 상실** |
`virsh destroy` 는 종료 신호를 보내지 않는다. **전원을 뽑는 것과 같다.**
---
## 0. 결론부터
| | 4a 워커 상실 | 4b 컨트롤 플레인 상실 |
|---|---|---|
| 외부 응답 | **503** | **000** (연결 자체가 안 됨) |
| `kubectl` | 정상 | **불통** |
| 살아 있는 워크로드 | keycloak-1 (하지만 DB 없음) | **keycloak-0 은 계속 돌고 있다** |
| 복구 시간 | **60초** | **60초** |
**둘 다 전면 장애**지만 이유가 다르다. 4a 는 **DB 가 같이 죽어서**, 4b 는
**들어갈 길이 없어서**다.
그리고 예상하지 못한 것 셋 —
**죽은 파드가 산 파드보다 건강해 보이고**, **StatefulSet 은 대체 파드를 만들지
않으며**, **PVC 때문에 재배치가 불가능하다.**
---
## 4a. 워커 노드 상실 (`kc-lab-2`)
### 기준선
```
kc-lab-1 Ready control-plane=true
kc-lab-2 Ready <none>
keycloak-0 ready=true kc-lab-2
keycloak-1 ready=true kc-lab-1
postgres ready=true kc-lab-2
PVC postgres-data → kc-lab-2 ← 재배치 가능성을 여기서 이미 알 수 있다
외부 HTTP 200
```
### 주입
```bash
virsh destroy kc-lab-2
```
### 관찰
```
+15초 node=Ready | keycloak-0=Running postgres=Running | 외부 HTTP 000
+30초 node=Ready | keycloak-0=Running postgres=Running | 외부 HTTP 000
+45초 node=NotReady | keycloak-0=Running postgres=Running | 외부 HTTP 503
...
+180초 node=NotReady | keycloak-0=Running postgres=Running | 외부 HTTP 503
```
### 발견 ① — 쿠버네티스가 알아채는 데 **40초** 걸린다
`+15초`, `+30초` 에도 노드는 여전히 `Ready` 다. **기계는 이미 없는데.**
kube-controller-manager 의 `node-monitor-grace-period` (기본 40초) 동안
kubelet 의 하트비트가 없어야 `NotReady` 로 바꾼다.
> **그 40초 동안 쿠버네티스는 거짓말을 한다.** 사용자는 이미 장애를 겪고 있다
> (`000`). **노드 상태를 알림 근거로 삼으면 항상 늦는다.**
### 발견 ② — **죽은 파드가 산 파드보다 건강해 보인다**
```
POD PHASE READY NODE
keycloak-0 Running true kc-lab-2 ← 기계가 꺼져 있다
keycloak-1 Running false kc-lab-1 ← 살아 있다
```
**`keycloak-0``ready=true`, `keycloak-1``ready=false`.**
| 왜 | |
|---|---|
| keycloak-0 | kubelet 이 없어 **상태를 갱신할 수 없다.** 마지막으로 보고한 값이 그대로 얼어 있다 |
| keycloak-1 | 살아서 **정직하게 보고한다** — DB 가 없으니 readiness 실패 |
> **파드 상태는 "지금 어떤가"가 아니라 "마지막으로 그렇게 들었다"이다.**
> 노드가 죽으면 그 노드 파드의 상태는 **화석**이 된다.
Prometheus 는 정확했다.
```
up{job=keycloak pod=keycloak-1} = 1
up{job=keycloak pod=keycloak-0} = 0 ← 긁기에 실패했다 = 사실
up{job=kubelet } = 0
up{job=node-exporter node=kc-lab-2 } = 0
```
**A-2 와 정반대다.** A-2 에서는 `up=1` 인데 서비스가 죽었고, 여기서는 `up=0`
이 정확했다.
| | `up` 이 잡는가 |
|---|---|
| **대상이 사라짐** (노드 상실) | **잡는다** |
| **대상이 살아서 못 씀** (DB 상실) | **못 잡는다** |
![up 이 노드별로 0 으로 떨어졌다](evidence/a4-node-loss/a4-up-dropped-per-node.png)
### 발견 ③ — 축출은 **5분** 뒤에 시작된다
쿠버네티스가 노드에 taint 를 붙인다.
```
node.kubernetes.io/unreachable=:NoSchedule
node.kubernetes.io/unreachable=:NoExecute
```
그런데 모든 파드에는 기본 관용이 붙어 있다.
```
node.kubernetes.io/not-ready NoExecute tolerationSeconds=300
node.kubernetes.io/unreachable NoExecute tolerationSeconds=300
```
```
+240초 전부 Running
+270초 a2-probe:Terminating keycloak-0:Terminating postgres:Terminating
postgres-...-9cmsv:Pending ← 새 파드가 생겼다
```
**노드가 죽고 약 5분이 지나야 파드가 축출된다.** 잠깐 끊긴 노드가 돌아올 수도
있으니 성급하게 옮기지 않겠다는 설계다. 대신 **그동안은 아무 일도 일어나지
않는다.**
### 발견 ④ — 축출돼도 **갈 곳이 없다**
```
Warning FailedScheduling default-scheduler
0/2 nodes are available:
1 node(s) didn't match PersistentVolume's node affinity,
1 node(s) had untolerated taint(s).
```
```
kc-lab-2 → taint 때문에 못 간다 (죽은 노드)
kc-lab-1 → PVC 가 kc-lab-2 에 묶여 있어 못 간다
```
**`local-path` PVC 는 그 노드의 로컬 디스크 디렉터리다.** 노드가 죽으면
볼륨도 죽는다. 새 파드는 **영원히 Pending** 이다.
> 결함이 아니라 **조건**이다. 이 실험대는 그걸 알고 `local-path` 를 골랐다.
> 운영이라면 네트워크 스토리지나 DB 복제가 이 자리를 메워야 한다.
### 발견 ⑤ — StatefulSet 은 **대체 파드를 만들지 않는다**
```
NAME DESIRED READY CURRENT
keycloak 2 <none> 1
keycloak-0 1/1 Terminating 30m ← 30분째
keycloak-1 0/1 Running
```
**`keycloak-0``Terminating` 에서 영원히 멈춰 있고, 대체 파드가 안 생긴다.**
| 왜 | |
|---|---|
| StatefulSet 의 계약 | **같은 이름의 파드는 클러스터에 하나뿐**이어야 한다 |
| 컨트롤 플레인이 아는 것 | 노드가 안 보인다 = **파드가 죽었는지 확신할 수 없다** |
| 그래서 | 옛 파드를 확실히 지우기 전엔 새 `keycloak-0` 을 못 만든다 |
**Deployment 였다면 즉시 새 파드를 만든다.** 이름이 아무래도 되기 때문이다.
StatefulSet 의 "안정된 이름"이라는 이득의 **반대편 비용**이 여기다.
강제로 진행시키려면 사람이 개입해야 한다.
```bash
kubectl -n keycloak-lab delete pod keycloak-0 --grace-period=0 --force
```
**위험한 명령이다.** 노드가 사실은 살아 있고 네트워크만 끊긴 것이라면
**같은 이름의 파드 둘이 동시에 존재**하게 된다 (split brain).
### 복구
```bash
virsh start kc-lab-2
```
```
+30초 node=Ready | Running 파드 3 개 | 외부 HTTP 503
+60초 node=Ready | Running 파드 3 개 | 외부 HTTP 200
→ 서비스 복귀
```
**60초.** 사람 개입 없이 전부 제자리로 돌아왔다.
---
## 4b. 컨트롤 플레인 노드 상실 (`kc-lab-1`)
### 이 노드에 무엇이 있었나 — 그게 곧 영향 범위다
```
keycloak-lab keycloak-1
kube-system coredns
kube-system local-path-provisioner
kube-system metrics-server
kube-system svclb-traefik
kube-system traefik ← replicas=1
observability grafana
observability prometheus
observability node-exporter
```
```
NAME REPLICAS READY
traefik 1 1 ← 진입점이 한 개다
```
### 주입과 관찰
```bash
virsh destroy kc-lab-1
```
```
+20초 외부 auth=000 grafana=000 | kubectl: Unable to connect to the server
+60초 외부 auth=000 grafana=000 | kubectl: Unable to connect to the server
+120초 외부 auth=000 grafana=502 | kubectl: Unable to connect to the server
+160초 외부 auth=000 grafana=000 | kubectl: Unable to connect to the server
```
### 발견 ⑥ — 워크로드는 살아 있는데 **길이 없다**
살아남은 노드에서 직접 확인했다.
```bash
ssh kc-lab-2 'sudo crictl ps --name keycloak'
```
```
CONTAINER STATE NAME POD NAMESPACE
e5f777900b76 Running keycloak keycloak-0 keycloak-lab
```
**`keycloak-0` 은 멀쩡히 돌고 있다.** 컨테이너 런타임(containerd)은 API 서버
없이도 이미 떠 있는 파드를 계속 굴린다.
```
죽은 것: API 서버 · 스케줄러 · coredns · Traefik · Prometheus · Grafana
산 것: keycloak-0 · postgres · containerd
문제: 들어갈 문(Traefik)이 없다
```
> **컨트롤 플레인 상실은 워크로드 상실이 아니다.**
> 이미 떠 있는 것은 계속 돈다. **새로 뜨거나 옮기거나 고치는 것이 안 될 뿐.**
### 발견 ⑦ — `000` 과 `503` 의 차이
| 코드 | 뜻 |
|---|---|
| **`503`** (4a) | nginx·Traefik 은 살아 있고 **뒤에 보낼 파드가 없다** |
| **`000`** (4b) | curl 이 응답 자체를 못 받았다 — **Traefik 이 없어 nginx 가 죽은 주소를 기다리다 타임아웃** |
`grafana=502` 가 한 번 찍힌 것이 증거다 — nginx 는 살아서 502 를 만들 수
있었지만, 대부분은 타임아웃(`--max-time 8`)에 걸렸다.
**두 코드가 다른 층의 고장을 가리킨다.**
### 발견 ⑧ — 관측 시스템이 같이 죽으면 **0 이 아니라 구멍이 남는다**
Prometheus 가 `kc-lab-1` 에 있었다. 그 노드가 죽은 12:18–12:23 구간은
그래프에 **0 이 아니라 데이터 없음**으로 남는다.
```
대상이 죽음 → up = 0 → "언제 죽었는지" 알 수 있다
관측자가 죽음 → 데이터 없음 → "그때 무슨 일이 있었는지" 모른다
```
**계획 단계에서 "관측 스택은 죽이지 않는 노드에 둔다"고 정했던 이유**를
실제로 확인한 셈이다. 다만 노드가 둘뿐이라 완전히 피할 수는 없다.
### 복구
```bash
virsh start kc-lab-1
```
```
+30초 외부=502 | kc-lab-1=Ready kc-lab-2=Ready
+60초 외부=200 | kc-lab-1=Ready kc-lab-2=Ready
→ 서비스 복귀 (총 60초)
```
**Grafana 는 로그인 세션을 잃었다** — 데이터가 `emptyDir` 이라 파드 재시작에
사라진다. Prometheus 는 PVC 라 지표가 남았다. **의도한 설계대로 동작했다.**
---
## 5. 개념
### `node-monitor-grace-period` 와 `tolerationSeconds`
```
기계 정지
│ 40초 node-monitor-grace-period → 노드 NotReady
│ +300초 tolerationSeconds (NoExecute) → 파드 축출 시작
총 약 5분 40초 동안 쿠버네티스는 아무것도 하지 않는다
```
**빠른 장애 대응이 필요하면 이 값을 줄여야 하지만**, 짧게 하면 일시적
네트워크 끊김에도 파드를 옮기게 되어 **불안정해진다.** 맞바꿈이다.
### `Terminating` 이 안 끝나는 이유
```
파드 삭제 요청
└─ kubelet 이 컨테이너를 멈추고 "지웠다"고 보고해야 끝난다
└─ kubelet 이 없다 → 보고가 없다 → 영원히 Terminating
```
`--grace-period=0 --force` 는 **보고를 기다리지 않고 API 에서 지우는 것**이다.
컨테이너가 실제로 죽었는지는 **모른 채** 진행한다.
### StatefulSet vs Deployment — 노드 상실에서
| | Deployment | StatefulSet |
|---|---|---|
| 대체 파드 | **즉시 만든다** (이름 무관) | **안 만든다** (이름이 유일해야) |
| 노드 상실 시 | 자동 회복 | **사람이 강제 삭제해야** |
| 위험 | 없음 | 강제 삭제 시 **중복 실행 가능** |
**A-0 에서 "로그 대조가 쉬워서" StatefulSet 을 골랐는데, 그 대가가 여기 있다.**
### `local-path` PVC 와 재배치
```
PVC → PV → nodeAffinity: kubernetes.io/hostname = kc-lab-2
└─ 그 노드의 /var/lib/rancher/k3s/storage/... 디렉터리
```
**볼륨이 노드에 못박히면 파드도 못박힌다.** 노드가 죽으면 데이터도 함께
접근 불가가 된다.
---
## 6. 재현 절차 (명령어)
```bash
export LIBVIRT_DEFAULT_URI=qemu:///system
# 사전 — PVC 가 어디 묶여 있는지 먼저 본다 (재배치 가능성이 여기서 정해진다)
kubectl -n keycloak-lab get pvc -o name | while read p; do
V=$(kubectl -n keycloak-lab get $p -o jsonpath='{.spec.volumeName}')
kubectl get pv $V -o jsonpath='{.spec.nodeAffinity.required.nodeSelectorTerms[0].matchExpressions[0].values[0]}'
done
# 4a 워커 상실
virsh destroy kc-lab-2
kubectl get node kc-lab-2 # 40초 뒤 NotReady
kubectl -n keycloak-lab get pods -o wide # Running 인 채로 얼어 있다
kubectl get node kc-lab-2 -o jsonpath='{.spec.taints}'
# 5분 뒤 Terminating + 새 파드 Pending
kubectl -n keycloak-lab describe pod <new-pod> | grep -A4 Events
# 4b 컨트롤 플레인 상실 — kubectl 이 죽으므로 노드에서 직접 본다
virsh destroy kc-lab-1
ssh kc-lab-2 'sudo crictl ps' # 워크로드는 살아 있다
# 복구
virsh start kc-lab-2 && virsh start kc-lab-1
```
---
## 7. 다음 실험에 남기는 것
| 실험 | 이 실험이 준 것 |
|---|---|
| **A-5** 비대칭 파티션 | 여기서는 노드가 **완전히** 사라졌다. 부분 단절은 더 고약하다 |
| **D-1** 백업·복구 | **PVC 가 노드에 묶여 있다** — 노드가 영영 안 돌아오면 백업이 유일한 길 |
| 구성 개선 | **Traefik `replicas=1` 은 진입점 단일 장애점** — 2로 늘리거나 DaemonSet 으로 |
| 구성 개선 | **Grafana 가 `emptyDir`** — 재시작마다 로그인 세션이 사라진다 |