examples: Add Alarm Manager Example

Closes: vmware#2783
Signed-off-by: Michael Gasch <mgasch@vmware.com>

examples/alarms/main.go

@@ -0,0 +1,58 @@
+package main
+
+import (
+	"context"
+	"flag"
+	"fmt"
+
+	"github.com/dougm/pretty"
+
+	"github.com/vmware/govmomi/examples"
+	"github.com/vmware/govmomi/property"
+	"github.com/vmware/govmomi/vim25"
+	"github.com/vmware/govmomi/vim25/methods"
+	"github.com/vmware/govmomi/vim25/mo"
+	"github.com/vmware/govmomi/vim25/types"
+)
+
+func main() {
+	var limit int
+	flag.IntVar(&limit, "limit", 10, "maximum number of alarms to retrieve")
+
+	examples.Run(func(ctx context.Context, c *vim25.Client) error {
+		pc := property.DefaultCollector(c)
+		am := c.ServiceContent.AlarmManager
+
+		fmt.Println("retrieving all alarms")
+		alarms, err := methods.GetAlarm(ctx, c, &types.GetAlarm{
+			This:   *am,
+			Entity: nil, // if not set, alarms are returned for all visible entities
+		})
+		if err != nil {
+			return fmt.Errorf("could not get alarms: %w", err)
+		}
+
+		counter := 0
+		for _, a := range alarms.Returnval {
+			counter++
+			fmt.Printf("retrieving details for alarm %q\n", a.String())
+
+			var info mo.Alarm
+			if err = pc.RetrieveOne(ctx, a, nil, &info); err != nil {
+				return fmt.Errorf("retrieve alarm info: %w", err)
+			}
+
+			_, err = pretty.Println(info)
+			if err != nil {
+				return fmt.Errorf("print alarm: %w", err)
+			}
+
+			if counter == limit {
+				fmt.Printf("reached maximum number of alarms to read (limit=%d)\n", limit)
+				break
+			}
+		}
+
+		return nil
+	})
+}