`nix/host-modules/swarm-peers-removed.nix` exists to turn an "option does
not exist" error into a warning that says where the entries went. That
warning is its whole deliverable, and no fixture set `swarm.peers` — the
string appeared 0 times in module-eval.nix, so the shim was never
evaluated by anything.
It differs from its ten siblings in what a broken shim looks like. The
others re-route a value, so a failure shows up as a wrong rendered
config. This one renders prose nothing reads back, so a `mkIf` that
stops matching or a rename of the `swarm.hives` it points at fails
silently, and lands on the one operator who needed it.
The check already carries an old-path fixture for ten migrated
namespaces (wireguard, forge, matrix, nats, authelia, controller, ui,
stores, grafana, statusPublish). `swarm.peers` was the eleventh and the
only uncovered one.
Two peers, only one carrying `caCert`, because the module emits a second
warning filtered on exactly that attribute — with a single peer the
filtered list and `attrNames` are the same list, so a `withCaCert` that
had collapsed into `attrNames` would still read green. The third case is
the control: a hive that never set `peers` must get neither warning,
without which the other two pass on any config whose warning list
happens to carry the string.
Closes#4188.
f918cea957