Admin: Add promotional page for Grafana Enterprise (#21422)

Co-authored-by: Torkel Ödegaard <torkel@grafana.com>

pkg/services/licensing/oss.go

@@ -0,0 +1,41 @@
+package licensing
+
+import (
+	"github.com/grafana/grafana/pkg/api/dtos"
+	"github.com/grafana/grafana/pkg/services/hooks"
+	"github.com/grafana/grafana/pkg/setting"
+)
+
+type OSSLicensingService struct {
+	Cfg          *setting.Cfg        `inject:""`
+	HooksService *hooks.HooksService `inject:""`
+}
+
+func (*OSSLicensingService) HasLicense() bool {
+	return false
+}
+
+func (*OSSLicensingService) Expiry() int64 {
+	return 0
+}
+
+func (l *OSSLicensingService) Init() error {
+	l.HooksService.AddIndexDataHook(func(indexData *dtos.IndexViewData) {
+		for _, node := range indexData.NavTree {
+			if node.Id == "admin" {
+				node.Children = append(node.Children, &dtos.NavLink{
+					Text: "Upgrade",
+					Id:   "upgrading",
+					Url:  l.Cfg.AppSubUrl + "/admin/upgrading",
+					Icon: "fa fa-fw fa-unlock-alt",
+				})
+			}
+		}
+	})
+
+	return nil
+}
+
+func (*OSSLicensingService) HasValidLicense() bool {
+	return false
+}