metrics: measure run operations for exec operations

This measures the duration of exec operations. It does not factor in
whether the operation was cached or not so this should include the
amount of time to determine whether an operation was cached.

Signed-off-by: Jonathan A. Sternberg <jonathan.sternberg@docker.com>

util/progress/metricwriter.go

@@ -24,6 +24,7 @@ func newMetrics(mp metric.MeterProvider, attrs attribute.Set) *metricWriter {
 		recorders: []metricRecorder{
 			newLocalSourceTransferMetricRecorder(meter, attrs),
 			newImageSourceTransferMetricRecorder(meter, attrs),
+			newExecMetricRecorder(meter, attrs),
 		},
 		attrs: attrs,
 	}
@@ -238,3 +239,40 @@ var reImageSourceType = regexp.MustCompile(`^\[.*] FROM `)
 func detectImageSourceType(vertexName string) bool {
 	return reImageSourceType.MatchString(vertexName)
 }
+
+type (
+	execMetricRecorder struct {
+		// Attributes holds the attributes for this metric recorder.
+		Attributes attribute.Set
+
+		// Duration tracks the duration of exec statements.
+		Duration metric.Float64Counter
+	}
+)
+
+func newExecMetricRecorder(meter metric.Meter, attrs attribute.Set) *execMetricRecorder {
+	mr := &execMetricRecorder{
+		Attributes: attrs,
+	}
+	mr.Duration, _ = meter.Float64Counter("exec.command.time",
+		metric.WithDescription("Measures the length of time spent executing run statements."),
+		metric.WithUnit("ms"))
+	return mr
+}
+
+func (mr *execMetricRecorder) Record(ss *client.SolveStatus) {
+	for _, v := range ss.Vertexes {
+		if v.Started == nil || v.Completed == nil || !detectExecType(v.Name) {
+			continue
+		}
+
+		dur := float64(v.Completed.Sub(*v.Started)) / float64(time.Millisecond)
+		mr.Duration.Add(context.Background(), dur, metric.WithAttributeSet(mr.Attributes))
+	}
+}
+
+var reExecType = regexp.MustCompile(`^\[.*] RUN `)
+
+func detectExecType(vertexName string) bool {
+	return reExecType.MatchString(vertexName)
+}