Michal 11344eab92 labsim: the IPAM switch needs no pod recycle when the CIDR sources agree ...

Re-ran the 3-node rehearsal, this time from a state that matches production
rather than one I had accidentally skewed.

The earlier "two nodes swapped CIDRs" result was an artefact of my own setup:
labsim had been running cluster-pool with per-node CIDRs that differed from
node.spec, I flipped it to ipam=kubernetes (which resyncs CiliumNode from
node.spec), and flipping back therefore looked like a renumber. Production has
only ever run ipam=kubernetes, and all five nodes were checked: CiliumNode and
node.spec agree everywhere.

From that matching state the switch is close to a non-event: per-node CIDRs
unchanged, every pod still inside its node's range, nothing stranded, no recycle
required. The only disruption is the cilium DaemonSet restarting itself -- one
agent sat in Init:0/6 and one node briefly took the agent-not-ready taint, both
of which cleared on their own. Cross-node connectivity verified after.

So the recycle is CONDITIONAL, not a fixed step, and `verify` is what decides.
Documented both cases in the script header, because the dangerous one is silent:
stranded pods report Running and Ready while being unreachable.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01DMVzWZgiKW2wquf5z8S1yH

2026-08-24 23:20:16 +01:00

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