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
 			}

pkg/util/util.go

@@ -141,17 +141,17 @@ func Coalesce(val, defaultVal string) string {
 	return val
 }
 
-// RequestIsSmallerThanLimit : ...
-func RequestIsSmallerThanLimit(requestStr, limitStr string) (bool, error) {
+// IsSmallerQuantity : checks if first resource is of a smaller quantity than the second
+func IsSmallerQuantity(requestStr, limitStr string) (bool, error) {
 
 	request, err := resource.ParseQuantity(requestStr)
 	if err != nil {
-		return false, fmt.Errorf("could not parse memory request %v : %v", requestStr, err)
+		return false, fmt.Errorf("could not parse request %v : %v", requestStr, err)
 	}
 
 	limit, err2 := resource.ParseQuantity(limitStr)
 	if err2 != nil {
-		return false, fmt.Errorf("could not parse memory limit %v : %v", limitStr, err2)
+		return false, fmt.Errorf("could not parse limit %v : %v", limitStr, err2)
 	}
 
 	return request.Cmp(limit) == -1, nil

pkg/util/util_test.go

@@ -69,7 +69,7 @@ var substringMatch = []struct {
 	{regexp.MustCompile(`aaaa (\d+) bbbb`), "aaaa 123 bbbb", nil},
 }
 
-var requestIsSmallerThanLimitTests = []struct {
+var requestIsSmallerQuantityTests = []struct {
 	request string
 	limit   string
 	out     bool
@@ -155,9 +155,9 @@ func TestMapContains(t *testing.T) {
 	}
 }
 
-func TestRequestIsSmallerThanLimit(t *testing.T) {
-	for _, tt := range requestIsSmallerThanLimitTests {
-		res, err := RequestIsSmallerThanLimit(tt.request, tt.limit)
+func TestIsSmallerQuantity(t *testing.T) {
+	for _, tt := range requestIsSmallerQuantityTests {
+		res, err := IsSmallerQuantity(tt.request, tt.limit)
 		if err != nil {
 			t.Errorf("RequestIsSmallerThanLimit returned unexpected error: %#v", err)
 		}