Add possibility to set max db connections

Since it's an important part of a connection pool configuration, allow
to configure max db connections, that pool will open to a target db.
From this numbers several others (like default pool size, min pool size,
reserve) will be deduced, taking into account desired number of instances.

pkg/util/config/config.go

@@ -94,6 +94,7 @@ type ConnectionPool struct {
 	ConnPoolDefaultMemoryRequest string `name:"connection_pool_default_memory_request" default:"100Mi"`
 	ConnPoolDefaultCPULimit      string `name:"connection_pool_default_cpu_limit" default:"3"`
 	ConnPoolDefaultMemoryLimit   string `name:"connection_pool_default_memory_limit" default:"1Gi"`
+	MaxDBConnections             *int32 `name:"connection_pool_max_db_connections" default:"60"`
 }
 
 // Config describes operator config

pkg/util/constants/pooler.go

@@ -11,5 +11,7 @@ const (
 	ConnectionPoolDefaultMemoryRequest = "100Mi"
 	ConnectionPoolDefaultMemoryLimit   = "100Mi"
 
-	ConnPoolContainer = 0
+	ConnPoolContainer            = 0
+	ConnPoolMaxDBConnections     = 60
+	ConnPoolMaxClientConnections = 10000
 )

pkg/util/k8sutil/k8sutil.go

@@ -28,7 +28,7 @@ import (
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 )
 
-func int32ToPointer(value int32) *int32 {
+func Int32ToPointer(value int32) *int32 {
 	return &value
 }
 
@@ -301,7 +301,7 @@ func (mock *mockDeployment) Get(name string, opts metav1.GetOptions) (*apiappsv1
 			Name: "test-deployment",
 		},
 		Spec: apiappsv1.DeploymentSpec{
-			Replicas: int32ToPointer(1),
+			Replicas: Int32ToPointer(1),
 			Template: v1.PodTemplateSpec{
 				Spec: v1.PodSpec{
 					Containers: []v1.Container{
@@ -318,7 +318,7 @@ func (mock *mockDeployment) Get(name string, opts metav1.GetOptions) (*apiappsv1
 func (mock *mockDeployment) Patch(name string, t types.PatchType, data []byte, subres ...string) (*apiappsv1.Deployment, error) {
 	return &apiappsv1.Deployment{
 		Spec: apiappsv1.DeploymentSpec{
-			Replicas: int32ToPointer(2),
+			Replicas: Int32ToPointer(2),
 		},
 		ObjectMeta: metav1.ObjectMeta{
 			Name: "test-deployment",

pkg/util/util.go

@@ -141,6 +141,22 @@ func Coalesce(val, defaultVal string) string {
 	return val
 }
 
+// Yeah, golang
+func CoalesceInt32(val, defaultVal *int32) *int32 {
+	if val == nil {
+		return defaultVal
+	}
+	return val
+}
+
+func MaxInt32(a, b *int32) *int32 {
+	if *a > *b {
+		return a
+	}
+
+	return b
+}
+
 // IsSmallerQuantity : checks if first resource is of a smaller quantity than the second
 func IsSmallerQuantity(requestStr, limitStr string) (bool, error) {