18947: Merge branch 'main'

Arvados-DCO-1.1-Signed-off-by: Tom Clegg <tom@curii.com>

diff --cc cmd/arvados-server/cmd.go
index 27c53eb5cb6393623f4e596e610006448e4d786a,ae1e3fbeee2d1e2d4310bb3f221b1f14bf77b17b..3a1fcd4c64e29b981ddb0234f1bf3eae6a14da7b
--- 1/cmd/arvados-server/cmd.go
--- 2/cmd/arvados-server/cmd.go
+++ b/cmd/arvados-server/cmd.go
@@@ -95,7 -90,3 +95,17 @@@ func (wb2command) RunCommand(prog strin
        }
        return 0
  }
- var healthCommand cmd.Handler = service.Command(arvados.ServiceNameHealth, func(ctx context.Context, cluster *arvados.Cluster, _ string, _ *prometheus.Registry) service.Handler {
-       return &health.Aggregator{Cluster: cluster}
 +
++var healthCommand cmd.Handler = service.Command(arvados.ServiceNameHealth, func(ctx context.Context, cluster *arvados.Cluster, _ string, reg *prometheus.Registry) service.Handler {
++      mClockSkew := prometheus.NewGauge(prometheus.GaugeOpts{
++              Namespace: "arvados",
++              Subsystem: "health",
++              Name:      "clock_skew_seconds",
++              Help:      "Clock skew observed in most recent health check",
++      })
++      reg.MustRegister(mClockSkew)
++      return &health.Aggregator{
++              Cluster:         cluster,
++              MetricClockSkew: mClockSkew,
++      }
 +})