code works now

.gitignore

@@ -1 +1,2 @@
-vm-metrics
+vm-metrics
+log.txt

main.go

@@ -2,11 +2,13 @@ package main
 
 import (
 	"context"
+	"encoding/json"
 	"flag"
 	"fmt"
 	"log"
 	"net/url"
 	"os"
+	"reflect"
 	"strings"
 	"time"
 	_ "time/tzdata"
@@ -27,8 +29,28 @@ var (
 	location  *time.Location
 	sha1ver   string // sha1 revision used to build the program
 	buildTime string // when the executable was built
+	results   []DrsResults
 )
 
+type DrsResults struct {
+	ClusterName            string
+	DrsScore               int32
+	Vcenter                string
+	NumVmsDrsBucket0To20   int32
+	NumVmsDrsBucket21To40  int32
+	NumVmsDrsBucket41To60  int32
+	NumVmsDrsBucket61To80  int32
+	NumVmsDrsBucket81To100 int32
+}
+
+// From https://github.com/vmware/govmomi/blob/main/performance/manager.go#L197
+/*
+type groupPerfCounterInfo struct {
+	info map[int32]*types.PerfCounterInfo
+	ids  []types.PerfMetricId
+}
+*/
+
 /*
 	func findPerfCounter(perfManager *vim25.PerformanceManager, counterName string) (*vim25.PerfCounterInfo, error) {
 		perfCounters, err := perfManager.QueryPerfCounter(context.Background(), nil)
@@ -61,15 +83,45 @@ func findVMByName(ctx context.Context, client *vim25.Client, vmName string) ([]m
 		return nil, err
 	}
 
-	var result []mo.VirtualMachine
+	// Temporarily just return all VMs
+	return matchingVMs, nil
 
-	for _, vm := range matchingVMs {
-		if vm.Name == vmName {
-			result = append(result, vm)
+	/*
+		var result []mo.VirtualMachine
+
+		for _, vm := range matchingVMs {
+			if vm.Name == vmName {
+				result = append(result, vm)
+			}
+		}
+
+		return result, nil
+	*/
+
+}
+
+func findClusterByName(ctx context.Context, client *vim25.Client, name string) mo.ClusterComputeResource {
+	// Create a container view so that we can search vCenter
+	m := view.NewManager(client)
+	cv, _ := m.CreateContainerView(ctx, c.ServiceContent.RootFolder, []string{"ClusterComputeResource"}, true)
+
+	var clusters []mo.ClusterComputeResource
+	log.Printf("Searching for Cluster '%s'\n", name)
+	err := cv.Retrieve(ctx, []string{"ClusterComputeResource"}, []string{"summary", "name"}, &clusters)
+	if err != nil {
+		log.Printf("Failed searching for Cluster %s : %s\n", name, err)
+		return mo.ClusterComputeResource{}
+	} else {
+		for _, cluster := range clusters {
+			if cluster.Name == name {
+				log.Printf("Found corresponding Cluster with MoRef '%s'\n", cluster.Reference())
+				return cluster
+			}
 		}
 	}
 
-	return result, nil
+	// If we reached here then we didn't find the Cluster
+	return mo.ClusterComputeResource{}
 }
 
 func getMetricIds(counters []types.PerfCounterInfo) []types.PerfMetricId {
@@ -79,6 +131,7 @@ func getMetricIds(counters []types.PerfCounterInfo) []types.PerfMetricId {
 		metricId.CounterId = counter.Key
 		metricIds = append(metricIds, metricId)
 	}
+	fmt.Printf("metric IDs : '%v'\n", metricIds)
 	return metricIds
 }
 
@@ -86,11 +139,15 @@ func getSpecificVMMetrics(ctx context.Context, c *vim25.Client, vmName string) {
 	//perfManager := c.ServiceContent.PerfManager
 	perfManager := performance.NewManager(c)
 	var perfCounterInfos []types.PerfCounterInfo
+	var perfCounterNames []string
 	startTime := time.Now().Add(-time.Hour)
 	timeNow := time.Now()
 
 	// Find the performance counters for CPU Entitlement, CPU Consumed, and CPU Demand
-	counterNames := []string{"cpu.entitlement.latest", "cpu.usage.average", "cpu.demand.average"}
+	// % Entitled Resource Delivered = Consumed/(min(Demand,Entitlement)) * 100
+	// As per https://www.unknownfault.com/posts/how-is-percentage-entitled-resource/
+	counterNames := []string{"cpu.entitlement.latest", "cpu.usagemhz.none", "cpu.demand.average"}
+	//counterNames := []string{"cpu.entitlement.latest"}
 
 	// Retrieve counters name list
 	counters, err := perfManager.CounterInfoByName(ctx)
@@ -103,12 +160,19 @@ func getSpecificVMMetrics(ctx context.Context, c *vim25.Client, vmName string) {
 	fmt.Printf("Found '%d' counters\n", len(counters))
 
 	for _, counter := range counters {
+
+		perfCounterNames = append(perfCounterNames, counter.Name())
+
 		for _, counterName := range counterNames {
 			if counter.Name() == counterName {
-				fmt.Printf("Found counter matching name '%s' : '%v'\n", counterName, counter.PerDeviceLevel)
+				groupInfo := counter.GroupInfo.GetElementDescription()
+				nameInfo := counter.NameInfo.GetElementDescription()
+
+				fmt.Printf("Found counter matching name '%s' : '%s';'%s'\n", counterName, groupInfo, nameInfo)
+
 				perfCounterInfos = append(perfCounterInfos, *counter)
 			} else {
-				//fmt.Printf("Ignoring '%s' : '%s'\n", counter.StatsType, counter.Name())
+				log.Printf("Ignoring '%s' : '%s'\n", counter.StatsType, counter.Name())
 			}
 		}
 	}
@@ -122,30 +186,113 @@ func getSpecificVMMetrics(ctx context.Context, c *vim25.Client, vmName string) {
 		return
 	}
 
-	for _, vm := range vmMatches {
-		// Create PerfQuerySpec as per https://github.com/vmware/govmomi/blob/main/performance/example_test.go
-		spec := types.PerfQuerySpec{
-			MaxSample:  1800,
-			MetricId:   getMetricIds(perfCounterInfos),
-			IntervalId: 20,
-			StartTime:  &startTime, // 1 hour ago
-			EndTime:    &timeNow,
-		}
+	//fmt.Printf("Processing %d vm matches : %v\n", len(vmMatches), vmMatches)
 
-		// Query metrics
-		sample, err := perfManager.SampleByName(ctx, spec, counterNames, []types.ManagedObjectReference{vm.Reference()})
+	var vmReferences []types.ManagedObjectReference
+
+	for _, vm := range vmMatches {
+		vmReferences = append(vmReferences, vm.Reference())
+	}
+
+	//fmt.Printf("Processing %d vm references : %v\n", len(vmReferences), vmReferences)
+
+	// Create PerfQuerySpec as per https://github.com/vmware/govmomi/blob/main/performance/example_test.go
+	spec := types.PerfQuerySpec{
+		//MaxSample:  180, // In one hour there are 180 instances of 20 second intervals
+		MetricId:   getMetricIds(perfCounterInfos),
+		IntervalId: 20,
+		StartTime:  &startTime, // 1 hour ago
+		EndTime:    &timeNow,
+	}
+
+	// Query metrics
+	//sample, err := perfManager.SampleByName(ctx, spec, counterNames, []types.ManagedObjectReference{vm.Reference()})
+	/*
+		sample, err := perfManager.SampleByName(ctx, spec, counterNames, vmReferences)
 		if err != nil {
 			fmt.Printf("Error getting SampleByName : '%s'\n", err)
 			return
 		}
+		fmt.Printf("Sample result is %d\n", len(sample))
+	*/
 
-		result, err := perfManager.ToMetricSeries(ctx, sample)
-		if err != nil {
-			fmt.Printf("Error getting ToMetricSeries : '%s'\n", err)
-			return
+	var query []types.PerfQuerySpec
+
+	for _, e := range vmMatches {
+		spec.Entity = e.Reference()
+		query = append(query, spec)
+	}
+
+	sample, err := perfManager.Query(ctx, query)
+	if err != nil {
+		fmt.Printf("Error running query : '%s'\n", err)
+		return
+	}
+
+	/*
+		for _, v := range sample {
+			fmt.Printf("%v\n", v.GetPerfEntityMetricBase().Entity)
+		}
+	*/
+
+	allCounters, err := perfManager.CounterInfoByKey(ctx)
+	if err != nil {
+		fmt.Printf("Error getting CounterInfoByKey : '%s'\n", err)
+		return
+	}
+
+	var result []performance.EntityMetric
+
+	for i := range sample {
+		fmt.Printf("Processing sample %d\n", i)
+		var values []performance.MetricSeries
+		s, ok := sample[i].(*types.PerfEntityMetric)
+		if !ok {
+			panic(fmt.Errorf("expected type %T, got: %T", s, sample[i]))
+		}
+		fmt.Printf("Found %d samples\n", len(s.Value))
+		//fmt.Printf("%v\n", sample[i])
+
+		for j := range s.Value {
+			v := s.Value[j].(*types.PerfMetricIntSeries)
+			info, ok := allCounters[v.Id.CounterId]
+			if !ok {
+				continue
+			}
+
+			vm := object.NewVirtualMachine(c, s.Entity)
+			entityName, err := vm.ObjectName(ctx)
+			if err != nil {
+				fmt.Printf("Error getting vm name : '%s'\n", err)
+				return
+			}
+			fmt.Printf("%s\t%s\t%s\t%v (%s)\n", entityName, info.Name(), v.Id.Instance, v.Value, info.UnitInfo.GetElementDescription().Key)
+
+			/*
+				values = append(values, performance.MetricSeries{
+					Name:     info.Name(),
+					unit:     info.UnitInfo.GetElementDescription().Key,
+					Instance: v.Id.Instance,
+					Value:    v.Value,
+				})
+			*/
 		}
 
-		fmt.Printf("Retrieved %d metric series\n", len(result))
+		result = append(result, performance.EntityMetric{
+			Entity:     s.Entity,
+			SampleInfo: s.SampleInfo,
+			Value:      values,
+		})
+	}
+	/*
+			result, err := perfManager.ToMetricSeries(ctx, sample)
+			if err != nil {
+				fmt.Printf("Error getting ToMetricSeries : '%s'\n", err)
+				return
+			}
+
+			fmt.Printf("Retrieved %d metric series\n", len(result))
+
 
 		// Read result
 		for _, metric := range result {
@@ -156,9 +303,10 @@ func getSpecificVMMetrics(ctx context.Context, c *vim25.Client, vmName string) {
 				return
 			}
 
-			fmt.Printf("Vm %s has %d metric values\n", name, len(metric.Value))
+			fmt.Printf("Vm %s has %d metric values : %v\n", name, len(metric.Value), metric)
 
-			for _, v := range metric.Value {
+			for i, v := range metric.Value {
+				fmt.Printf("Processing [%d] : '%v'\n", i, v)
 
 				counter := counters[v.Name]
 				units := counter.UnitInfo.GetElementDescription().Label
@@ -169,32 +317,48 @@ func getSpecificVMMetrics(ctx context.Context, c *vim25.Client, vmName string) {
 				}
 
 				if len(v.Value) != 0 {
-					fmt.Printf("%s\t%s\t%s\t%s : %v\n", name, instance, v.Name, units, v.ValueCSV())
+					//fmt.Printf("%s\t%s\t%s\t%s : %v\n", name, instance, v.Name, units, v.ValueCSV())
+					fmt.Printf("%s\t%s\t%s\t%s : %v\n", name, instance, v.Name, units, v.Value)
 				}
 			}
 		}
 
-		/*
-			// Create a query specification
-			query := perfManager.QueryPerf(ctx, &vim25.QueryPerf{
-				Entity:     []vim25.ManagedObjectReference{vm.Reference()},
-				MaxSample:  1,
-				MetricId:   getMetricIds(perfCounterInfos),
-				IntervalId: 20,                         // 20-second interval
-				StartTime:  time.Now().Add(-time.Hour), // 1 hour ago
-				EndTime:    time.Now(),
-			})
+		fmt.Printf("Finished receiving result.\n")
+	*/
 
-			// Process the query result
-			for _, perf := range query {
-				fmt.Println("VM:", vmName)
-				for i, value := range perf.Value {
-					counterInfo := perfCounterInfos[i]
-					fmt.Printf("%s: %v\n", counterInfo.NameInfo.GetElement().Key, value.Value[0])
-				}
+	/*
+		// Create a query specification
+		query := perfManager.QueryPerf(ctx, &vim25.QueryPerf{
+			Entity:     []vim25.ManagedObjectReference{vm.Reference()},
+			MaxSample:  1,
+			MetricId:   getMetricIds(perfCounterInfos),
+			IntervalId: 20,                         // 20-second interval
+			StartTime:  time.Now().Add(-time.Hour), // 1 hour ago
+			EndTime:    time.Now(),
+		})
+
+		// Process the query result
+		for _, perf := range query {
+			fmt.Println("VM:", vmName)
+			for i, value := range perf.Value {
+				counterInfo := perfCounterInfos[i]
+				fmt.Printf("%s: %v\n", counterInfo.NameInfo.GetElement().Key, value.Value[0])
 			}
-		*/
-	}
+		}
+	*/
+}
+
+// From https://stackoverflow.com/a/33769379
+func Scan(d interface{}) {
+	v := reflect.ValueOf(d)
+	i := reflect.Indirect(v)
+	s := i.Type()
+	println(s.NumField()) // will print out 0, if you change Host to have 1 field, it prints out 1
+}
+
+func query(t reflect.Type) {
+	value := reflect.New(t).Interface()
+	Scan(value)
 }
 
 func main() {
@@ -252,4 +416,17 @@ func main() {
 	defer c.Logout(ctx)
 
 	getSpecificVMMetrics(ctx, c.Client, *vmName)
+	//err = getNumVmsPerDrsScoreBucket(c)
+	if err != nil {
+		log.Printf("Error retrieving NumVmsPerDrsScoreBucket: %s\n", err)
+		return
+	}
+
+	// Output final results in JSON
+	if len(results) > 0 {
+		j, _ := json.Marshal(results)
+		fmt.Println(string(j))
+	} else {
+		fmt.Println("{}")
+	}
 }