feat(agent): expose imp_vm_guest_cpu_iowait_ratio OTel gauge

Author: syscod3

internal/agent/firecracker_driver.go

@@ -559,7 +559,9 @@ func (d *FirecrackerDriver) pollMetrics(ctx context.Context, client pb.GuestAgen
 				logf.Log.V(1).Info("pollMetrics: guest agent unavailable", "vm", vmKey, "err", err)
 				continue
 			}
-			d.Metrics.SetGuestMetrics(vmKey, d.NodeName, className, resp.CpuUsageRatio, resp.MemoryUsedBytes, resp.DiskUsedBytes)
+			d.Metrics.SetGuestMetrics(vmKey, d.NodeName, className,
+				resp.CpuUsageRatio, resp.CpuIowaitRatio,
+				resp.MemoryUsedBytes, resp.DiskUsedBytes)
 		}
 	}
 }

internal/agent/metrics.go

@@ -22,11 +22,12 @@ type vmStateEntry struct {
 }
 
 type guestData struct {
-	cpu   float64
-	mem   float64
-	disk  float64
-	node  string
-	class string
+	cpu    float64
+	iowait float64
+	mem    float64
+	disk   float64
+	node   string
+	class  string
 }
 
 // VMMetricsCollector holds per-VM metric state for the node agent.
@@ -85,6 +86,25 @@ func NewVMMetricsCollector(meter metric.Meter, gatherer prometheus.Gatherer) *VM
 		}),
 	)
 
+	_, _ = meter.Float64ObservableGauge(
+		"imp_vm_guest_cpu_iowait_ratio",
+		metric.WithDescription("Guest VM CPU iowait ratio (0.0–1.0)."),
+		metric.WithFloat64Callback(func(_ context.Context, o metric.Float64Observer) error {
+			c.mu.RLock()
+			defer c.mu.RUnlock()
+			for key, d := range c.guestMetrics {
+				ns, name := splitKey(key)
+				o.Observe(d.iowait, metric.WithAttributes(
+					attribute.String("impvm", name),
+					attribute.String("namespace", ns),
+					attribute.String("node", d.node),
+					attribute.String("impvmclass", d.class),
+				))
+			}
+			return nil
+		}),
+	)
+
 	_, _ = meter.Float64ObservableGauge(
 		"imp_vm_guest_memory_used_bytes",
 		metric.WithDescription("Guest VM memory used bytes."),
@@ -134,15 +154,16 @@ func (c *VMMetricsCollector) SetVMState(key, state, node string) {
 }
 
 // SetGuestMetrics updates guest agent metrics for a VM.
-func (c *VMMetricsCollector) SetGuestMetrics(key, node, impvmclass string, cpu float64, mem, disk int64) {
+func (c *VMMetricsCollector) SetGuestMetrics(key, node, impvmclass string, cpu, iowait float64, mem, disk int64) {
 	c.mu.Lock()
 	defer c.mu.Unlock()
 	c.guestMetrics[key] = &guestData{
-		cpu:   cpu,
-		mem:   float64(mem),
-		disk:  float64(disk),
-		node:  node,
-		class: impvmclass,
+		cpu:    cpu,
+		iowait: iowait,
+		mem:    float64(mem),
+		disk:   float64(disk),
+		node:   node,
+		class:  impvmclass,
 	}
 }
 

internal/agent/metrics_test.go

@@ -63,7 +63,7 @@ func TestVMMetrics_clearVMRemovesState(t *testing.T) {
 
 func TestVMMetrics_guestMetricsAppear(t *testing.T) {
 	mc, h := newTestCollector(t)
-	mc.SetGuestMetrics("default/test-vm", "test-node", "small", 0.5, 512*1024*1024, 1024*1024*1024)
+	mc.SetGuestMetrics("default/test-vm", "test-node", "small", 0.5, 0.1, 512*1024*1024, 1024*1024*1024)
 
 	req := httptest.NewRequest(http.MethodGet, "/metrics", nil)
 	w := httptest.NewRecorder()
@@ -72,6 +72,7 @@ func TestVMMetrics_guestMetricsAppear(t *testing.T) {
 	body := w.Body.String()
 	for _, metric := range []string{
 		"imp_vm_guest_cpu_usage_ratio",
+		"imp_vm_guest_cpu_iowait_ratio",
 		"imp_vm_guest_memory_used_bytes",
 		"imp_vm_guest_disk_used_bytes",
 	} {