From 39be6f85acf52ec25bb0d1c80ad847f9dc87cb09 Mon Sep 17 00:00:00 2001
From: "W. Trevor King" <wking@tremily.us>
Date: Tue, 26 Apr 2022 15:27:23 -0700
Subject: [PATCH] pkg/controller/daemon: Log misscheduled node

So administrators have some idea at how to debug, when they notice that
status.numberMisscheduled > 0, e.g. because KubeDaemonSetMisScheduled
is firing.

Ideally we'd have status.conditions on DaemonSet [1], so we could
declare things like this in a more discoverable location.  But while
logs aren't all that discoverable, they are easier to add than a new
DaemonSet property.  And we can mitigate discoverability by filling
out [2] and linking [3] a runbook to recommend grepping the controller
logs for this message.

[1]: https://github.com/kubernetes/enhancements/issues/120#issuecomment-252856758
[2]: https://github.com/kubernetes-monitoring/kubernetes-mixin/blob/5c2dd2c63c8d655bdb7717f695d02bd22bd180e8/runbook.md#alert-name-kubedaemonsetmisscheduled
[3]: https://github.com/kubernetes-monitoring/kubernetes-mixin/blob/5c2dd2c63c8d655bdb7717f695d02bd22bd180e8/alerts/apps_alerts.libsonnet#L224-L237
---
 pkg/controller/daemon/daemon_controller.go | 1 +
 1 file changed, 1 insertion(+)

diff --git a/pkg/controller/daemon/daemon_controller.go b/pkg/controller/daemon/daemon_controller.go
index e31dde1eaccdc..ef05d97349060 100644
--- a/pkg/controller/daemon/daemon_controller.go
+++ b/pkg/controller/daemon/daemon_controller.go
@@ -1147,6 +1147,7 @@ func (dsc *DaemonSetsController) updateDaemonSetStatus(ctx context.Context, ds *
 			}
 		} else {
 			if scheduled {
+				klog.V(2).InfoS("Found misscheduled daemon set pod", "daemonSet", klog.KObj(ds), "node", node.Name)
 				numberMisscheduled++
 			}
 		}