Updated robig/cron.v2 to robig/cron.v3, i.e. v3.0.1

Several race conditions and other things have been updated between the
the different versions. Per various issues being reported in deleting
PostgreSQL Operator schedules, it seemed appropriate to attempt to fix
them by updating the library, as we have had mixed success reproducing
the issue (evident of a race).

Issue: [ch6933]

Author: Jonathan S. Katz

Gopkg.lock

@@ -10,10 +10,6 @@ version = "6.0.0"
 name = "k8s.io/api"
 version = "kubernetes-1.9.0"
 
-[[constraint]]
-branch = "v2"
-name = "gopkg.in/robfig/cron.v2"
-
 [[constraint]]
   name = "github.com/nsqio/go-nsq"
   version = "v1.0.7"
@@ -26,3 +22,6 @@ name = "gopkg.in/robfig/cron.v2"
   name = "gopkg.in/yaml.v2"
   version = ">=v2.2.3" # < 2.2.3 has a DoS vuln
 
+[[constraint]]
+  name = "gopkg.in/robfig/cron.v3"
+  version = "3.0.1"

Gopkg.toml

@@ -25,7 +25,7 @@ import (
 	"github.com/crunchydata/postgres-operator/apiserver"
 	log "github.com/sirupsen/logrus"
 
-	cv2 "gopkg.in/robfig/cron.v2"
+	cv2 "gopkg.in/robfig/cron.v3"
 	"k8s.io/api/core/v1"
 	"k8s.io/client-go/kubernetes"
 )

pgo-scheduler/scheduler/scheduler.go

@@ -21,7 +21,7 @@ import (
 	"k8s.io/client-go/kubernetes"
 	"k8s.io/client-go/rest"
 
-	cv2 "gopkg.in/robfig/cron.v2"
+	cv2 "gopkg.in/robfig/cron.v3"
 )
 
 var kubeClient *kubernetes.Clientset

pgo-scheduler/scheduler/types.go

@@ -20,7 +20,7 @@ import (
 	"fmt"
 	"strings"
 
-	cv2 "gopkg.in/robfig/cron.v2"
+	cv3 "gopkg.in/robfig/cron.v3"
 )
 
 func validate(s ScheduleTemplate) error {
@@ -44,8 +44,12 @@ func validate(s ScheduleTemplate) error {
 	return nil
 }
 
+// ValidateSchedule validates that the cron syntax is valid
+// We use the standard format here...
 func ValidateSchedule(schedule string) error {
-	if _, err := cv2.Parse(schedule); err != nil {
+	parser := cv3.NewParser(cv3.Minute | cv3.Hour | cv3.Dom | cv3.Month | cv3.Dow)
+
+	if _, err := parser.Parse(schedule); err != nil {
 		return fmt.Errorf("%s is not a valid schedule: ", schedule)
 	}
 	return nil