Add CIDR for microcluster Network Interface Configuration

docs/src/_parts/commands/k8s_bootstrap.md

@@ -13,7 +13,7 @@ k8s bootstrap [flags]
 ### Options
 
 ```
-      --address string         microcluster address, defaults to the node IP address
+      --address string         microcluster address or CIDR, defaults to the node IP address
       --file string            path to the YAML file containing your custom cluster bootstrap configuration. Use '-' to read from stdin.
   -h, --help                   help for bootstrap
       --interactive            interactively configure the most important cluster options

docs/src/_parts/commands/k8s_join-cluster.md

@@ -9,7 +9,7 @@ k8s join-cluster <join-token> [flags]
 ### Options
 
 ```
-      --address string         microcluster address, defaults to the node IP address
+      --address string         microcluster address or CIDR, defaults to the node IP address
       --file string            path to the YAML file containing your custom cluster join configuration. Use '-' to read from stdin.
   -h, --help                   help for join-cluster
       --name string            node name, defaults to hostname

src/k8s/cmd/k8s/k8s_bootstrap.go

@@ -16,7 +16,6 @@ import (
 	cmdutil "github.com/canonical/k8s/cmd/util"
 	"github.com/canonical/k8s/pkg/config"
 	"github.com/canonical/k8s/pkg/utils"
-	"github.com/canonical/lxd/lxd/util"
 	"github.com/spf13/cobra"
 	"gopkg.in/yaml.v2"
 )
@@ -73,10 +72,14 @@ func newBootstrapCmd(env cmdutil.ExecutionEnvironment) *cobra.Command {
 				}
 			}
 
-			if opts.address == "" {
-				opts.address = util.NetworkInterfaceAddress()
+			address, err := utils.ParseAddressString(opts.address, config.DefaultPort)
+			if err != nil {
+				cmd.PrintErrf("Error: Failed to parse the address %q.\n\nThe error was: %v\n", opts.address, err)
+				env.Exit(1)
+				return
 			}
-			opts.address = util.CanonicalNetworkAddress(opts.address, config.DefaultPort)
+
+			opts.address = address
 
 			client, err := env.Client(cmd.Context())
 			if err != nil {
@@ -147,7 +150,7 @@ func newBootstrapCmd(env cmdutil.ExecutionEnvironment) *cobra.Command {
 	cmd.Flags().BoolVar(&opts.interactive, "interactive", false, "interactively configure the most important cluster options")
 	cmd.Flags().StringVar(&opts.configFile, "file", "", "path to the YAML file containing your custom cluster bootstrap configuration. Use '-' to read from stdin.")
 	cmd.Flags().StringVar(&opts.name, "name", "", "node name, defaults to hostname")
-	cmd.Flags().StringVar(&opts.address, "address", "", "microcluster address, defaults to the node IP address")
+	cmd.Flags().StringVar(&opts.address, "address", "", "microcluster address or CIDR, defaults to the node IP address")
 	cmd.Flags().StringVar(&opts.outputFormat, "output-format", "plain", "set the output format to one of plain, json or yaml")
 	cmd.Flags().DurationVar(&opts.timeout, "timeout", 90*time.Second, "the max time to wait for the command to execute")
 

src/k8s/cmd/k8s/k8s_join_cluster.go

@@ -10,7 +10,7 @@ import (
 	apiv1 "github.com/canonical/k8s/api/v1"
 	cmdutil "github.com/canonical/k8s/cmd/util"
 	"github.com/canonical/k8s/pkg/config"
-	"github.com/canonical/lxd/lxd/util"
+	"github.com/canonical/k8s/pkg/utils"
 	"github.com/spf13/cobra"
 )
 
@@ -55,10 +55,14 @@ func newJoinClusterCmd(env cmdutil.ExecutionEnvironment) *cobra.Command {
 				opts.name = hostname
 			}
 
-			if opts.address == "" {
-				opts.address = util.NetworkInterfaceAddress()
+			address, err := utils.ParseAddressString(opts.address, config.DefaultPort)
+			if err != nil {
+				cmd.PrintErrf("Error: Failed to parse the address %q.\n\nThe error was: %v\n", opts.address, err)
+				env.Exit(1)
+				return
 			}
-			opts.address = util.CanonicalNetworkAddress(opts.address, config.DefaultPort)
+
+			opts.address = address
 
 			client, err := env.Client(cmd.Context())
 			if err != nil {
@@ -110,7 +114,7 @@ func newJoinClusterCmd(env cmdutil.ExecutionEnvironment) *cobra.Command {
 		},
 	}
 	cmd.Flags().StringVar(&opts.name, "name", "", "node name, defaults to hostname")
-	cmd.Flags().StringVar(&opts.address, "address", "", "microcluster address, defaults to the node IP address")
+	cmd.Flags().StringVar(&opts.address, "address", "", "microcluster address or CIDR, defaults to the node IP address")
 	cmd.Flags().StringVar(&opts.configFile, "file", "", "path to the YAML file containing your custom cluster join configuration. Use '-' to read from stdin.")
 	cmd.Flags().StringVar(&opts.outputFormat, "output-format", "plain", "set the output format to one of plain, json or yaml")
 	cmd.Flags().DurationVar(&opts.timeout, "timeout", 90*time.Second, "the max time to wait for the command to execute")

src/k8s/pkg/utils/cidr.go

@@ -4,9 +4,32 @@ import (
 	"fmt"
 	"math/big"
 	"net"
+	"strconv"
 	"strings"
+
+	"github.com/canonical/lxd/lxd/util"
 )
 
+// FindMatchingNodeAddress returns the IP address of a network interface that belongs to the given CIDR.
+func FindMatchingNodeAddress(cidr *net.IPNet) (net.IP, error) {
+	addrs, err := net.InterfaceAddrs()
+	if err != nil {
+		return nil, fmt.Errorf("could not get interface addresses: %w", err)
+	}
+
+	for _, addr := range addrs {
+		ipNet, ok := addr.(*net.IPNet)
+		if !ok {
+			continue
+		}
+		if cidr.Contains(ipNet.IP) {
+			return ipNet.IP, nil
+		}
+	}
+
+	return nil, fmt.Errorf("could not find a matching address for CIDR %q", cidr.String())
+}
+
 // GetFirstIP returns the first IP address of a subnet. Use big.Int so that it can handle both IPv4 and IPv6 addreses.
 func GetFirstIP(subnet string) (net.IP, error) {
 	_, cidr, err := net.ParseCIDR(subnet)
@@ -37,3 +60,30 @@ func GetKubernetesServiceIPsFromServiceCIDRs(serviceCIDR string) ([]net.IP, erro
 	}
 	return firstIPs, nil
 }
+
+// ParseAddressString parses an address string and returns a canonical network address.
+func ParseAddressString(address string, port int64) (string, error) {
+	host, hostPort, err := net.SplitHostPort(address)
+	if err == nil {
+		address = host
+		port, err = strconv.ParseInt(hostPort, 10, 64)
+		if err != nil {
+			return "", fmt.Errorf("failed to parse the port from %q: %w", hostPort, err)
+		}
+	}
+
+	if address == "" {
+		address = util.NetworkInterfaceAddress()
+	}
+
+	if _, ipNet, err := net.ParseCIDR(address); err == nil {
+		matchingIP, err := FindMatchingNodeAddress(ipNet)
+		if err != nil {
+			return "", fmt.Errorf("failed to find a matching node address for %q: %w", address, err)
+		}
+		address = matchingIP.String()
+	}
+
+	return util.CanonicalNetworkAddress(address, port), nil
+
+}