add validation for PG resources and volume size

pkg/cluster/cluster.go

@@ -227,6 +227,10 @@ func (c *Cluster) Create() error {
 
 	c.setStatus(acidv1.ClusterStatusCreating)
 
+	if err = c.validateResources(&c.Spec); err != nil {
+		return fmt.Errorf("unsufficient ressources: %v", err)
+	}
+
 	for _, role := range []PostgresRole{Master, Replica} {
 
 		if c.Endpoints[role] != nil {
@@ -491,6 +495,53 @@ func compareResourcesAssumeFirstNotNil(a *v1.ResourceRequirements, b *v1.Resourc
 
 }
 
+func (c *Cluster) validateResources(spec *acidv1.PostgresSpec) error {
+
+	const (
+		cpuMinimum     = "256m"
+		memoryMinimum  = "256Mi"
+		storageMinimum = "1Gi"
+	)
+
+	var (
+		isSmaller bool
+		err       error
+	)
+
+	cpuLimit := spec.Resources.ResourceLimits.CPU
+	if cpuLimit != "" {
+		isSmaller, err = util.IsSmallerQuantity(cpuLimit, cpuMinimum)
+		if err != nil {
+			return fmt.Errorf("error validating CPU limit: %v", err)
+		}
+		if isSmaller {
+			return fmt.Errorf("defined CPU limit %s is below required minimum %s to properly run postgresql resource", cpuLimit, cpuMinimum)
+		}
+	}
+
+	memoryLimit := spec.Resources.ResourceLimits.Memory
+	if memoryLimit != "" {
+		isSmaller, err = util.IsSmallerQuantity(memoryLimit, memoryMinimum)
+		if err != nil {
+			return fmt.Errorf("error validating memory limit: %v", err)
+		}
+		if isSmaller {
+			return fmt.Errorf("defined memory limit %s is below required minimum %s to properly run postgresql resource", memoryLimit, memoryMinimum)
+		}
+	}
+
+	storageSize := spec.Volume.Size
+	isSmaller, err = util.IsSmallerQuantity(storageSize, storageMinimum)
+	if err != nil {
+		return fmt.Errorf("error validating volume size: %v", err)
+	}
+	if isSmaller {
+		return fmt.Errorf("defined volume size %s is below required minimum %s to properly run postgresql resource", storageSize, storageMinimum)
+	}
+
+	return nil
+}
+
 // Update changes Kubernetes objects according to the new specification. Unlike the sync case, the missing object
 // (i.e. service) is treated as an error
 // logical backup cron jobs are an exception: a user-initiated Update can enable a logical backup job

pkg/cluster/k8sres.go

@@ -740,7 +740,7 @@ func (c *Cluster) generateStatefulSet(spec *acidv1.PostgresSpec) (*appsv1.Statef
 			limit = c.OpConfig.DefaultMemoryLimit
 		}
 
-		isSmaller, err := util.RequestIsSmallerThanLimit(request, limit)
+		isSmaller, err := util.IsSmallerQuantity(request, limit)
 		if err != nil {
 			return nil, err
 		}
@@ -767,7 +767,7 @@ func (c *Cluster) generateStatefulSet(spec *acidv1.PostgresSpec) (*appsv1.Statef
 				limit = c.OpConfig.DefaultMemoryLimit
 			}
 
-			isSmaller, err := util.RequestIsSmallerThanLimit(sidecarRequest, sidecarLimit)
+			isSmaller, err := util.IsSmallerQuantity(sidecarRequest, sidecarLimit)
 			if err != nil {
 				return nil, err
 			}