Move getDatacenter to vsphere/datacenter_helper.go, add API handling

Moved getDatacenter to its own helper code, as a lot of other resources
use it. Also added the ability of it to detect the connected API type
(ESXi vs vCenter), and just use the default if on ESXi.

vsphere/datacenter_helper.go

@@ -0,0 +1,30 @@
+package vsphere
+
+import (
+	"fmt"
+
+	"github.com/vmware/govmomi"
+	"github.com/vmware/govmomi/find"
+	"github.com/vmware/govmomi/object"
+	"golang.org/x/net/context"
+)
+
+// getDatacenter gets the higher-level datacenter object for the datacenter
+// name supplied by dc.
+//
+// The default datacenter is denoted by using an empty string. When working
+// with ESXi directly, the default datacenter is always selected.
+func getDatacenter(c *govmomi.Client, dc string) (*object.Datacenter, error) {
+	finder := find.NewFinder(c.Client, true)
+	t := c.ServiceContent.About.ApiType
+	switch t {
+	case "HostAgent":
+		return finder.DefaultDatacenter(context.TODO())
+	case "VirtualCenter":
+		if dc != "" {
+			return finder.Datacenter(context.TODO(), dc)
+		}
+		return finder.DefaultDatacenter(context.TODO())
+	}
+	return nil, fmt.Errorf("unsupported ApiType: %s", t)
+}

vsphere/resource_vsphere_folder.go

@@ -223,15 +223,3 @@ func deleteFolder(client *govmomi.Client, f *folder) error {
 	}
 	return nil
 }
-
-// getDatacenter gets datacenter object
-func getDatacenter(c *govmomi.Client, dc string) (*object.Datacenter, error) {
-	finder := find.NewFinder(c.Client, true)
-	if dc != "" {
-		d, err := finder.Datacenter(context.TODO(), dc)
-		return d, err
-	} else {
-		d, err := finder.DefaultDatacenter(context.TODO())
-		return d, err
-	}
-}