Every scenario in the suite created its interface after the daemons were already running — that ordering is the boot race the suite was written for. But it means both nodes could only ever reach Present through binder_loop, so the inline bind in start_async, which is the ordinary case on a booted router, had no end-to-end coverage at all. That is where the churn guard went unseeded and the first detach stopped reaching node health, and no existing case could reach it: they all detach from a binding the loop created, which seeds the guard as a side effect. Case (f) adds a third node whose single required interface exists before its daemon does. The gate is what buys that ordering — the harness needs a running container to have a netns to move a veth into, but the daemon must not start until after the move, so node-c comes up parked on a file and the harness releases it once the interface is in place. Then one detach, on a binding the loop did not create, and the node must degrade. Verified against the defect rather than only against the fix: with the guard seed reverted, cases (a) through (e) all still pass and (f) is the only failure. A regression test that has never been seen to fail is a claim, not a test. It also asserts the reverse edge, so Degraded stays a level rather than a latch on this path too.
Dynamic Interface Binding
Two FIPS daemons whose only transports are bound to network interfaces, exercised against a veth pair the harness creates, downs, deletes and recreates underneath them while they run.
node-a node-b
lab ve-lab0 required ── veth ── ve-lab0 required
dock fips-dock0 optional fips-dock0 optional
ve-lab0 does not exist when the daemons start. fips-dock0 never exists at
all, on any host, ever — it is the negative control for optional: true.
What it asserts
| Behavior | |
|---|---|
| (a) | A daemon whose only interface is missing starts, reports the transport absent, and reports Degraded — it does not exit on NoTransports, and it does not skip the transport for the life of the process |
| (b) | The interface appears; both daemons bind it with no restart, Degraded clears, and they discover and peer over it |
| (c) | The interface goes down and comes back; presence and health follow it in both directions, and the rebind is counted |
| (d) | The interface is deleted outright and recreated; both daemons rebind and re-peer — the case the old ENXIO beacon-socket reopen half-covered |
| (e) | An optional interface that never appears logs at info and never moves node health |
| Absence is logged once on the edge, not once per retry |
Health is asserted through fipsctl show status (state), presence through
fipsctl show transports (the per-transport interface block: presence,
policy, binds, since_secs).
Running
./test.sh # builds the image first
./test.sh --skip-build # reuse an existing image
./test.sh --keep-up # leave the containers running for inspection
Via the local CI runner:
./testing/ci-local.sh --only iface-binding
Notes
The containers run under FIPS_TEST_MODE=default, not chaos. The chaos
entrypoint waits up to 30 s for every configured Ethernet interface before
starting the daemon — which is exactly the workaround this mechanism retires.
The daemon has to do its own waiting here or the suite proves nothing.
Every ip link operation on the host network stack runs inside a short-lived
privileged container sharing the host network and PID namespaces, for the
reason chaos/sim/veth.py documents: on macOS the
containers live in the Docker VM, so ip(8) run on the macOS host could never
reach them, while on Linux the shared namespaces make it identical to running
ip(8) directly.