feat: read the virtual IPs vip-manager and keepalived declare on a host

A virtual IP sits on whichever member holds it right now; a standby's address list shows no trace of it. What every member has is the configuration that declares it, and reading that is the same on every Linux host -- so VirtualIpsMixin.get_virtual_ips() lives here and a driver only carries the command across (NetOrk/netork#829). - vip-manager: every vip-manager.service / vip-manager@*.service unit; the address from a flag (1.x's -ip=${VIP_IP} resolved through the unit's environment), the environment, or the --config YAML (5.x). - keepalived: the virtual_ipaddress(_excluded) entries of every vrrp_instance, with its interface and virtual_router_id; include is followed four levels deep, and a pattern that is no plain path glob is never handed to the root shell. The same files hold the etcd password and auth_pass, so an awk program filters on the host and prints allowlisted fields only. None per mechanism is "did not look", [] a host without it. The command is about 4 kB and goes on an exec channel. Version 4.2.0.
2026-10-08 12:37:28 +02:00
parent 8111c4cde3
commit 37c09d0fa0
6 changed files with 1073 additions and 1 deletions
@@ -96,6 +96,17 @@ without `ss` is read with `netstat -lntup` (OpenWrt's busybox, old net-tools); o
 cgroup names the procd service (`/services/<name>/<instance>`). A host with neither raises
 `ListeningSocketsUnavailable`.

+`VirtualIpsMixin` (`get_virtual_ips`) reads the addresses a host's HA configuration lets
+float between machines: vip-manager (5.x's `--config` YAML, 1.x's `-ip=${VIP_IP}` resolved
+through the unit's environment) and keepalived (`virtual_ipaddress` of every
+`vrrp_instance`, `include` followed four levels deep). It reports what is *declared*, not
+what the host holds right now -- that is in its interface addresses. The same files hold
+the etcd password and `auth_pass`, so an awk program filters **on the host** and prints
+allowlisted fields only; a secret never reaches the caller. Root first, then without it.
+A mechanism it could not read completely is `None` ("did not look"), a host without it
+`[]`. The command is about 4 kB, so a driver sends it on an exec channel
+(`_run_virtual_ips_command(command, privileged=)`), not typed into a shell.
+
 **Update readers raise when they cannot read.** `get_available_updates` returns an empty
 list only when nothing is pending; netOrk keeps "pending since" per package, and an empty
 list for "don't know" would reset it.