Allow configuring pod priority globally and per cluster. (#353)

* Allow configuring pod priority globally and per cluster.

Allow to specify pod priority class for all pods managed by the operator,
as well as for those belonging to individual clusters.

Controlled by the pod_priority_class_name operator configuration
parameter and the podPriorityClassName manifest option.

See https://kubernetes.io/docs/concepts/configuration/pod-priority-preemption/#priorityclass
for the explanation on how to define priority classes since Kubernetes 1.8.

Some import order changes are due to go fmt.
Removal of OrphanDependents deprecated field.

Code review by @zerg-junior

pkg/spec/postgresql.go

@@ -8,8 +8,8 @@ import (
 	"strings"
 	"time"
 
-	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/api/core/v1"
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/apimachinery/pkg/runtime"
 )
 
@@ -127,14 +127,15 @@ type PostgresSpec struct {
 	// load balancers' source ranges are the same for master and replica services
 	AllowedSourceRanges []string `json:"allowedSourceRanges"`
 
-	NumberOfInstances  int32                `json:"numberOfInstances"`
-	Users              map[string]UserFlags `json:"users"`
-	MaintenanceWindows []MaintenanceWindow  `json:"maintenanceWindows,omitempty"`
-	Clone              CloneDescription     `json:"clone"`
-	ClusterName        string               `json:"-"`
-	Databases          map[string]string    `json:"databases,omitempty"`
-	Tolerations        []v1.Toleration      `json:"tolerations,omitempty"`
-	Sidecars           []Sidecar            `json:"sidecars,omitempty"`
+	NumberOfInstances    int32                `json:"numberOfInstances"`
+	Users                map[string]UserFlags `json:"users"`
+	MaintenanceWindows   []MaintenanceWindow  `json:"maintenanceWindows,omitempty"`
+	Clone                CloneDescription     `json:"clone"`
+	ClusterName          string               `json:"-"`
+	Databases            map[string]string    `json:"databases,omitempty"`
+	Tolerations          []v1.Toleration      `json:"tolerations,omitempty"`
+	Sidecars             []Sidecar            `json:"sidecars,omitempty"`
+	PodPriorityClassName string               `json:"pod_priority_class_name,omitempty"`
 }
 
 // PostgresqlList defines a list of PostgreSQL clusters.
@@ -182,7 +183,6 @@ func (p *Postgresql) DeepCopyObject() runtime.Object {
 	return nil
 }
 
-
 func parseTime(s string) (time.Time, error) {
 	parts := strings.Split(s, ":")
 	if len(parts) != 2 {

pkg/spec/types.go

@@ -11,10 +11,10 @@ import (
 	"time"
 
 	"github.com/Sirupsen/logrus"
-	"k8s.io/apimachinery/pkg/types"
-	"k8s.io/api/core/v1"
 	"k8s.io/api/apps/v1beta1"
+	"k8s.io/api/core/v1"
 	policyv1beta1 "k8s.io/api/policy/v1beta1"
+	"k8s.io/apimachinery/pkg/types"
 	"k8s.io/client-go/rest"
 )