Bond: Monitor bond mii_status not link operstate (#1124)

With a bond interface the state of the slave interface from the bond's
point of view is reflected in `mii_status` and is independent of the
link's `operstate`.

When a bond is monitored with `miimon`, `mii_status` will reflect the
state of the physical link as configured via the operator.

When a bond is monitored via `arp_interval` the `mii_status` will
reflect the results of the bond ARP checking.  This means the link can
be down from the bond's point of view, but up from a physical
connection point of view.

If a bond is not monitored via miimon or arp, the `mii_status` should
likely be always `up`, however I have observed a case where this is not
true and the `operstate` is `up` while `mii_status` is `down`.  Kernel
bond documentation stresses that a bond should not be configured without
one of `mii_mon` or `arp_interval` configured however.

This change results in the metric 'node_bonding_active' matching the
up/down state of the bond's point of view rather than operstate.

Signed-off-by: Sachi King <nakato@nakato.io>

1 files changed, 2 insertions, 2 deletions

diff --git a/collector/bonding_linux.go b/collector/bonding_linux.go
index 829ab6d..f67e2a3 100644
--- a/collector/bonding_linux.go
+++ b/collector/bonding_linux.go
@@ -82,10 +82,10 @@ func readBondingStats(root string) (status map[string][2]int, err error) {
                 }
                 sstat := [2]int{0, 0}
                 for _, slave := range strings.Fields(string(slaves)) {
-                        state, err := ioutil.ReadFile(filepath.Join(root, master, fmt.Sprintf("lower_%s", slave), "operstate"))
+                        state, err := ioutil.ReadFile(filepath.Join(root, master, fmt.Sprintf("lower_%s", slave), "bonding_slave", "mii_status"))
                         if os.IsNotExist(err) {
                                 // some older? kernels use slave_ prefix
-                                state, err = ioutil.ReadFile(filepath.Join(root, master, fmt.Sprintf("slave_%s", slave), "operstate"))
+                                state, err = ioutil.ReadFile(filepath.Join(root, master, fmt.Sprintf("slave_%s", slave), "bonding_slave", "mii_status"))
                         }
                         if err != nil {
                                 return nil, err