installconfig/gcp/validation: handle custom machine types

Prior to this change, the validation on gcp instance types would return
an error that the type did not exist. This change adds the logic to
properly handle custom machine types while validating their CPU and
Memeory values.

pkg/asset/installconfig/gcp/validation.go

@@ -6,6 +6,7 @@ import (
 	"fmt"
 	"net"
 	"net/http"
+	"strconv"
 	"strings"
 
 	"github.com/sirupsen/logrus"
@@ -66,6 +67,34 @@ func ValidateInstanceType(client API, ic *types.InstallConfig, fieldPath *field.
 			errMsg := fmt.Sprintf("instance type does not meet minimum resource requirements of %d MB Memory", req.minimumMemory)
 			allErrs = append(allErrs, field.Invalid(fieldPath.Child("type"), instanceType, errMsg))
 		}
+	} else if index := strings.Index(instanceType, "custom-"); index != -1 {
+
+		// Ensure the CPU and MEMORY are defined in custom instance type names
+		if customConfig := strings.Split(instanceType[index+len("custom-"):], "-"); len(customConfig) == 2 {
+
+			// Ensure the custom CPU is a valid integer
+			if customCpus, err := strconv.ParseInt(customConfig[0], 10, 0); err != nil {
+				errMsg := fmt.Sprintf("instance type %s is not a valid custom type", instanceType)
+				allErrs = append(allErrs, field.Invalid(fieldPath.Child("type"), instanceType, errMsg))
+			} else if customCpus < req.minimumVCpus {
+				errMsg := fmt.Sprintf("instance type does not meet minimum resource requirements of %d vCPUs", req.minimumVCpus)
+				allErrs = append(allErrs, field.Invalid(fieldPath.Child("type"), instanceType, errMsg))
+			}
+
+			// Ensure the custom Memory is a valid integer
+			if customMemory, err := strconv.ParseInt(customConfig[1], 10, 0); err != nil {
+				errMsg := fmt.Sprintf("instance type %s is not a valid custom type", instanceType)
+				allErrs = append(allErrs, field.Invalid(fieldPath.Child("type"), instanceType, errMsg))
+			} else if customMemory < req.minimumMemory {
+				errMsg := fmt.Sprintf("instance type does not meet minimum resource requirements of %d MB Memory", req.minimumMemory)
+				allErrs = append(allErrs, field.Invalid(fieldPath.Child("type"), instanceType, errMsg))
+			}
+
+		} else {
+			errMsg := fmt.Sprintf("instance type %s is not a valid custom type", instanceType)
+			allErrs = append(allErrs, field.Invalid(fieldPath.Child("type"), instanceType, errMsg))
+		}
+
 	} else {
 		errMsg := fmt.Sprintf("instance type %s not found", instanceType)
 		allErrs = append(allErrs, field.Invalid(fieldPath.Child("type"), instanceType, errMsg))