Specify globalCIDR while joining cluster

Enhance 'subctl join' to be able specify globalCIDR
for each cluster while joining. The logic implemented is

if globalcidr specified by user
  if globalcidr is preconfigured
    take pre-configured value
  else
    error if it overlaps with other clusters
    take specified value

if not specified by user
  if globalcidr is preconfigured
    take pre-configured value
  else automatically assign value

It also checks
* if the specified CIDR is valid
and that both globalcidr and globalnet cluster
size are not specified.
* if globalnet-cidr or globalnet-cluster-size
is specified even if globalnet is not enabled
and ignores its value.

Closes: submariner-io#298
Signed-off-by: Janki Chhatbar

pkg/subctl/cmd/join.go

@@ -21,6 +21,7 @@ import (
 	"errors"
 	"fmt"
 	"io"
+	"net"
 	"os"
 	"regexp"
 	"strings"
@@ -52,7 +53,7 @@ var (
 	clusterID            string
 	serviceCIDR          string
 	clusterCIDR          string
-	globalCIDR           string
+	globalnetCIDR        string
 	repository           string
 	imageVersion         string
 	nattPort             int
@@ -95,6 +96,8 @@ func addJoinFlags(cmd *cobra.Command) {
 		"disable OpenShift's cluster version operator if necessary, without prompting")
 	cmd.Flags().UintVar(&globalnetClusterSize, "globalnet-cluster-size", 0,
 		"Cluster size for GlobalCIDR allocated to this cluster (amount of global IPs)")
+	cmd.Flags().StringVar(&globalnetCIDR, "globalnet-cidr", "",
+		"GlobalCIDR to be allocated to the cluster")
 }
 
 const (
@@ -126,6 +129,8 @@ func checkArgumentPassed(args []string) error {
 	return nil
 }
 
+var status = cli.NewStatus()
+
 func joinSubmarinerCluster(config *rest.Config, subctlData *datafile.SubctlData) {
 
 	// Missing information
@@ -191,20 +196,14 @@ func joinSubmarinerCluster(config *rest.Config, subctlData *datafile.SubctlData)
 			colorCodes = answers.ColorCodes
 		}
 	}
-	if subctlData.GlobalnetCidrRange != "" && globalnetClusterSize != 0 && globalnetClusterSize != subctlData.GlobalnetClusterSize {
-		clusterSize, err := globalnet.GetValidClusterSize(subctlData.GlobalnetCidrRange, globalnetClusterSize)
-		if err != nil || clusterSize == 0 {
-			exitOnError("Invalid globalnet-cluster-size", err)
-		}
-		subctlData.GlobalnetClusterSize = clusterSize
-	}
+
+	validateGlobalnetConfiguration(subctlData)
 
 	if !noLabel {
 		err := handleNodeLabels(config)
 		exitOnError("Unable to set the gateway node up", err)
 	}
 
-	status := cli.NewStatus()
 	status.Start("Deploying the Submariner operator")
 	err := submarinerop.Ensure(status, config, OperatorNamespace, operatorImage)
 	status.End(err == nil)
@@ -237,16 +236,31 @@ func joinSubmarinerCluster(config *rest.Config, subctlData *datafile.SubctlData)
 		err = checkOverlappingClusterCidr(globalNetworks)
 		status.End(err == nil)
 		exitOnError("Error validating overlapping ClusterCIDRs", err)
-	} else if globalNetworks[clusterID] == nil || globalNetworks[clusterID].GlobalCIDRs == nil || len(globalNetworks[clusterID].GlobalCIDRs) <= 0 {
-		// Globalnet enabled, no globalCidr configured on this cluster
-		globalCIDR, err = globalnet.AllocateGlobalCIDR(globalNetworks, subctlData)
-		status.End(err == nil)
-		status.QueueSuccessMessage(fmt.Sprintf("Allocated GlobalCIDR: %s", globalCIDR))
-		exitOnError("Globalnet failed", err)
+	} else if globalnetCIDR == "" {
+		// Globalnet enabled, GlobalCIDR not specified by the user
+		if cidrIsPreConfigured(clusterID, globalNetworks) {
+			// globalCidr already configured on this cluster
+			globalnetCIDR = globalNetworks[clusterID].GlobalCIDRs[0]
+			status.QueueSuccessMessage(fmt.Sprintf("Cluster already has GlobalCIDR allocated: %s", globalNetworks[clusterID].GlobalCIDRs[0]))
+		} else {
+			// no globalCidr configured on this cluster
+			globalnetCIDR, err = globalnet.AllocateGlobalCIDR(globalNetworks, subctlData)
+			status.End(err == nil)
+			status.QueueSuccessMessage(fmt.Sprintf("Allocated GlobalCIDR: %s", globalnetCIDR))
+			exitOnError("Globalnet failed", err)
+		}
 	} else {
-		// Globalnet enabled, globalCidr already configured on this cluster
-		globalCIDR = globalNetworks[clusterID].GlobalCIDRs[0]
-		status.QueueSuccessMessage(fmt.Sprintf("Cluster already has GlobalCIDR allocated: %s", globalNetworks[clusterID].GlobalCIDRs[0]))
+		// Globalnet enabled, globalnetCIDR specified by user
+		if cidrIsPreConfigured(clusterID, globalNetworks) {
+			// globalCidr pre-configured on this cluster
+			globalnetCIDR = globalNetworks[clusterID].GlobalCIDRs[0]
+			status.QueueSuccessMessage(fmt.Sprintf("Pre-configured GlobalCIDR %s detected. Not changing it.", globalnetCIDR))
+		} else {
+			// globalCidr as specified by the user
+			err = checkOverlappingGlobalCidr(globalNetworks)
+			exitOnError(fmt.Sprintf("Error validating overlapping GlobalCIDRs %s", globalnetCIDR), err)
+			status.QueueSuccessMessage(fmt.Sprintf("GlobalCIDR is: %s", globalnetCIDR))
+		}
 	}
 
 	status.Start("Creating SA for cluster")
@@ -288,6 +302,19 @@ func checkOverlappingClusterCidr(networks map[string]*globalnet.GlobalNetwork) e
 	return nil
 }
 
+func checkOverlappingGlobalCidr(networks map[string]*globalnet.GlobalNetwork) error {
+	for k, v := range networks {
+		overlap, err := globalnet.IsOverlappingCIDR(v.GlobalCIDRs, globalnetCIDR)
+		if err != nil {
+			return fmt.Errorf("unable to validate overlapping GlobalCIDR: %s", err)
+		}
+		if overlap && k != clusterID {
+			return fmt.Errorf("invalid globalnet CIDR: %s overlaps with cluster %s", globalnetCIDR, k)
+		}
+	}
+	return nil
+}
+
 func getGlobalNetworks(subctlData *datafile.SubctlData) map[string]*globalnet.GlobalNetwork {
 
 	brokerConfig := subctlData.GetBrokerAdministratorConfig()
@@ -388,6 +415,45 @@ func isOpenShiftCVOEnabled(config *rest.Config) (bool, error) {
 	return scale.Spec.Replicas > 0, nil
 }
 
+func cidrIsPreConfigured(clusterID string, globalNetworks map[string]*globalnet.GlobalNetwork) bool {
+	// GlobalCIDR is not pre-configured
+	if globalNetworks[clusterID] == nil || globalNetworks[clusterID].GlobalCIDRs == nil || len(globalNetworks[clusterID].GlobalCIDRs) <= 0 {
+		return false
+	}
+	// GlobalCIDR is pre-configured
+	return true
+}
+
+func validateGlobalnetConfiguration(subctlData *datafile.SubctlData) {
+	if subctlData.GlobalnetCidrRange != "" && globalnetClusterSize != 0 && globalnetClusterSize != subctlData.GlobalnetClusterSize {
+		clusterSize, err := globalnet.GetValidClusterSize(subctlData.GlobalnetCidrRange, globalnetClusterSize)
+		if err != nil || clusterSize == 0 {
+			exitOnError("Invalid globalnet-cluster-size", err)
+		}
+		subctlData.GlobalnetClusterSize = clusterSize
+	}
+
+	if globalnetCIDR != "" && globalnetClusterSize != 0 {
+		err := errors.New("Both globalnet-cluster-size and globalnet-cidr can't be specified. Specify either one.\n")
+		exitOnError("Invalid configuration", err)
+	}
+
+	if globalnetCIDR != "" {
+		_, _, err := net.ParseCIDR(globalnetCIDR)
+		exitOnError("Specified globalnet-cidr is invalid", err)
+	}
+
+	if subctlData.GlobalnetCidrRange == "" {
+		if globalnetCIDR != "" {
+			status.QueueSuccessMessage("globalnet is not enabled on Broker. Ignoring specified globalnet-cidr\n")
+			globalnetCIDR = ""
+		} else if globalnetClusterSize != 0 {
+			status.QueueSuccessMessage("globalnet is not enabled on Broker. Ignoring specified globalnet-cluster-size\n")
+			globalnetClusterSize = 0
+		}
+	}
+}
+
 func populateSubmarinerSpec(subctlData *datafile.SubctlData) submariner.SubmarinerSpec {
 	brokerURL := subctlData.BrokerURL
 	if idx := strings.Index(brokerURL, "://"); idx >= 0 {
@@ -429,9 +495,8 @@ func populateSubmarinerSpec(subctlData *datafile.SubctlData) submariner.Submarin
 		CableDriver:              cableDriver,
 		ServiceDiscoveryEnabled:  subctlData.ServiceDiscovery,
 	}
-
-	if globalCIDR != "" {
-		submarinerSpec.GlobalCIDR = globalCIDR
+	if globalnetCIDR != "" {
+		submarinerSpec.GlobalCIDR = globalnetCIDR
 	}
 	return submarinerSpec
 }