rename to hostaliases and use rfc1123 regexp to validate hostnames

cmd/cluster/clusterCreate.go

@@ -32,6 +32,7 @@ import (
 
 	"github.com/docker/go-connections/nat"
 	"github.com/sirupsen/logrus"
+	"inet.af/netaddr"
 
 	"github.com/spf13/cobra"
 	"github.com/spf13/viper"
@@ -266,6 +267,9 @@ func NewCmdClusterCreate() *cobra.Command {
 	cmd.Flags().String("registry-create", "", "Create a k3d-managed registry and connect it to the cluster (Format: `NAME[:HOST][:HOSTPORT]`\n - Example: `k3d cluster create --registry-create mycluster-registry:0.0.0.0:5432`")
 	_ = ppViper.BindPFlag("cli.registries.create", cmd.Flags().Lookup("registry-create"))
 
+	cmd.Flags().StringArray("host-alias", nil, "Add `ip:host[,host,...]` mappings")
+	_ = ppViper.BindPFlag("hostaliases", cmd.Flags().Lookup("host-alias"))
+
 	/* k3s */
 	cmd.Flags().StringArray("k3s-arg", nil, "Additional args passed to k3s command (Format: `ARG@NODEFILTER[;@NODEFILTER]`)\n - Example: `k3d cluster create --k3s-arg \"--disable=traefik@server:0\"")
 	_ = ppViper.BindPFlag("cli.k3sargs", cmd.Flags().Lookup("k3s-arg"))
@@ -330,9 +334,6 @@ func NewCmdClusterCreate() *cobra.Command {
 	cmd.Flags().Bool("host-pid-mode", false, "Enable host pid mode of server(s) and agent(s)")
 	_ = cfgViper.BindPFlag("options.runtime.hostpidmode", cmd.Flags().Lookup("host-pid-mode"))
 
-	cmd.Flags().StringArray("extra-host", nil, "Add `host:ip` mappings")
-	_ = cfgViper.BindPFlag("extraHosts", cmd.Flags().Lookup("extra-host"))
-
 	/* Image Importing */
 	cmd.Flags().Bool("no-image-volume", false, "Disable the creation of a volume for importing images")
 	_ = cfgViper.BindPFlag("options.k3d.disableimagevolume", cmd.Flags().Lookup("no-image-volume"))
@@ -596,8 +597,41 @@ func applyCLIOverrides(cfg conf.SimpleConfig) (conf.SimpleConfig, error) {
 			cfg.Registries.Create.Host = exposeAPI.Host
 			cfg.Registries.Create.HostPort = exposeAPI.Binding.HostPort
 		}
+	}
+
+	// --host-alias
+	hostAliasFlags := ppViper.GetStringSlice("hostaliases")
+	l.Log().Debugf("HostAliasFlags: %+v", hostAliasFlags)
+	if len(hostAliasFlags) > 0 {
+		for _, ha := range hostAliasFlags {
 
+			// split on :
+			s := strings.Split(ha, ":")
+			if len(s) != 2 {
+				return cfg, fmt.Errorf("invalid format of host-alias %s (exactly one ':' allowed)", ha)
+			}
+
+			// validate IP // TODO: move to pkg/ validate config?
+			ip, err := netaddr.ParseIP(s[0])
+			if err != nil {
+				return cfg, fmt.Errorf("invalid IP '%s' in host-alias '%s': %w", s[0], ha, err)
+			}
+
+			// hostnames
+			hostnames := strings.Split(s[1], ",")
+			for _, hostname := range hostnames {
+				if err := k3dCluster.ValidateHostname(hostname); err != nil {
+					return cfg, fmt.Errorf("invalid hostname '%s' in host-alias '%s': %w", hostname, ha, err)
+				}
+			}
+
+			cfg.HostAliases = append(cfg.HostAliases, k3d.HostAlias{
+				IP:        ip.String(),
+				Hostnames: hostnames,
+			})
+		}
 	}
+	l.Log().Debugf("HostAliases: %+v", cfg.HostAliases)
 
 	return cfg, nil
 }

pkg/client/cluster.go

@@ -251,66 +251,56 @@ func ClusterPrep(ctx context.Context, runtime k3drt.Runtime, clusterConfig *conf
 	 * -> host:ip mappings
 	 */
 
-	if len(clusterConfig.ClusterCreateOpts.ExtraHosts) > 0 {
+	if len(clusterConfig.ClusterCreateOpts.HostAliases) > 0 {
 
-		extraHostsMap := map[string][]string{}
-		for _, extraHost := range clusterConfig.ClusterCreateOpts.ExtraHosts {
-			s := strings.Split(extraHost, ":")
-			if len(s) != 2 {
-				return fmt.Errorf("extra host entry '%s' had invalid format", extraHost)
-			}
-			extraHostsMap[s[1]] = append(extraHostsMap[s[1]], s[0])
-		}
-
-		if len(extraHostsMap) > 0 {
-			extraHostsInjectEtcHostsHook := k3d.NodeHook{
-				Stage: k3d.LifecycleStagePostStart,
-				Action: actions.RewriteFileAction{
-					Runtime:     runtime,
-					Path:        "/etc/hosts",
-					Mode:        0644,
-					Description: "Adding ExtraHosts to /etc/hosts in nodes",
-					Opts: actions.RewriteFileActionOpts{
-						NoCopy: true,
-					},
-					RewriteFunc: func(input []byte) ([]byte, error) {
+		hostAliasesInjectEtcHostsHook := k3d.NodeHook{
+			Stage: k3d.LifecycleStagePostStart,
+			Action: actions.RewriteFileAction{
+				Runtime:     runtime,
+				Path:        "/etc/hosts",
+				Mode:        0644,
+				Description: "Adding HostAliases to /etc/hosts in nodes",
+				Opts: actions.RewriteFileActionOpts{
+					NoCopy: true,
+				},
+				RewriteFunc: func(input []byte) ([]byte, error) {
 
-						// write copied hosts file to temp path (for hostsfile module to read)
-						tmpHosts, err := os.CreateTemp("", "k3d-hostsfile-*")
-						if err != nil {
-							return nil, fmt.Errorf("error creating temp hosts file: %w", err)
-						}
-						os.WriteFile(tmpHosts.Name(), input, 0777)
+					// write copied hosts file to temp path (for hostsfile module to read)
+					tmpHosts, err := os.CreateTemp("", "k3d-hostsfile-*")
+					if err != nil {
+						return nil, fmt.Errorf("error creating temp hosts file: %w", err)
+					}
+					os.WriteFile(tmpHosts.Name(), input, 0777)
 
-						// read in temp hostsfile file
-						hostsfile, err := hostsfile.NewCustomHosts(tmpHosts.Name())
-						if err != nil {
-							return nil, fmt.Errorf("error reading temp hosts file: %w", err)
-						}
+					// read in temp hostsfile file
+					hostsfile, err := hostsfile.NewCustomHosts(tmpHosts.Name())
+					if err != nil {
+						return nil, fmt.Errorf("error reading temp hosts file: %w", err)
+					}
 
-						// add new entries
-						for ip, hosts := range extraHostsMap {
-							if err := hostsfile.Add(ip, hosts...); err != nil {
-								return nil, fmt.Errorf("error adding hosts file entry for %s:%s: %w", ip, hosts, err)
-							}
+					// add new entries
+					for _, hostAlias := range clusterConfig.ClusterCreateOpts.HostAliases {
+						if err := hostsfile.Add(hostAlias.IP, hostAlias.Hostnames...); err != nil {
+							return nil, fmt.Errorf("error adding hosts file entry for %s:%s: %w", hostAlias.IP, hostAlias.Hostnames, err)
 						}
+					}
 
-						// cleanup (de-duplicate, etc.)
-						hostsfile.Clean()
+					// cleanup (de-duplicate, etc.)
+					hostsfile.Clean()
 
-						// write changes to temp file
-						hostsfile.Flush()
+					// write changes to temp file
+					hostsfile.Flush()
 
-						time.Sleep(time.Second)
+					time.Sleep(time.Second)
 
-						return os.ReadFile(tmpHosts.Name())
-					},
+					return os.ReadFile(tmpHosts.Name())
 				},
-			}
-
-			// append new action to general nodehooks
-			clusterConfig.ClusterCreateOpts.NodeHooks = append(clusterConfig.ClusterCreateOpts.NodeHooks, extraHostsInjectEtcHostsHook)
+			},
 		}
+
+		// append new action to general nodehooks
+		clusterConfig.ClusterCreateOpts.NodeHooks = append(clusterConfig.ClusterCreateOpts.NodeHooks, hostAliasesInjectEtcHostsHook)
+
 	}
 
 	return nil

pkg/client/clusterName.go

@@ -23,10 +23,14 @@ package client
 
 import (
 	"fmt"
+	"regexp"
 
 	"github.com/rancher/k3d/v5/pkg/types"
 )
 
+// HostnameRegexp as per RFC 1123
+var HostnameRegexp = regexp.MustCompile(`^(([a-zA-Z0-9]|[a-zA-Z0-9][a-zA-Z0-9\-]*[a-zA-Z0-9])\.)*([A-Za-z0-9]|[A-Za-z0-9][A-Za-z0-9\-]*[A-Za-z0-9])$`)
+
 // CheckName ensures that a cluster name is also a valid host name according to RFC 1123.
 // We further restrict the length of the cluster name to maximum 'clusterNameMaxSize'
 // so that we can construct the host names based on the cluster name, and still stay
@@ -48,21 +52,8 @@ func ValidateHostname(name string) error {
 		return fmt.Errorf("No name provided")
 	}
 
-	if name[0] == '-' || name[len(name)-1] == '-' {
-		return fmt.Errorf("Hostname '%s' must not start or end with '-' (dash)", name)
-	}
-
-	for _, c := range name {
-		switch {
-		case '0' <= c && c <= '9':
-		case 'a' <= c && c <= 'z':
-		case 'A' <= c && c <= 'Z':
-		case c == '-':
-			break
-		default:
-			return fmt.Errorf("Hostname '%s' contains characters other than 'Aa-Zz', '0-9' or '-'", name)
-
-		}
+	if !HostnameRegexp.Match([]byte(name)) {
+		return fmt.Errorf("name %s is not a valid hostname as per RFC 1123", name)
 	}
 
 	return nil

pkg/config/transform.go

@@ -279,7 +279,7 @@ func TransformSimpleToClusterConfig(ctx context.Context, runtime runtimes.Runtim
 		GPURequest:          simpleConfig.Options.Runtime.GPURequest,
 		ServersMemory:       simpleConfig.Options.Runtime.ServersMemory,
 		AgentsMemory:        simpleConfig.Options.Runtime.AgentsMemory,
-		ExtraHosts:          simpleConfig.ExtraHosts,
+		HostAliases:         simpleConfig.HostAliases,
 		GlobalLabels:        map[string]string{}, // empty init
 		GlobalEnv:           []string{},          // empty init
 	}

pkg/config/v1alpha3/schema.json

@@ -302,14 +302,22 @@
         "additionalProperties": false
       }
     },
-    "extraHosts": {
+    "hostAliases": {
       "type": "array",
-      "description": "Additional host:ip mappings in format `my.host.domain:1.2.3.4`",
+      "description": "Additional IP to multiple hostnames mappings",
       "items": {
-        "type": "string",
-        "examples": [
-          "my.host.domain:1.2.3.4"
-        ]
+        "type": "object",
+        "properties": {
+          "ip": {
+            "type": "string"
+          },
+          "hostnames": {
+            "type": "array",
+            "items": {
+              "type": "string"
+            }
+          }
+        }
       }
     }
   },

pkg/config/v1alpha3/types.go

@@ -29,6 +29,7 @@ import (
 	"time"
 
 	config "github.com/rancher/k3d/v5/pkg/config/types"
+	"github.com/rancher/k3d/v5/pkg/types"
 	k3d "github.com/rancher/k3d/v5/pkg/types"
 	"github.com/rancher/k3d/v5/version"
 )
@@ -155,7 +156,7 @@ type SimpleConfig struct {
 	Options         SimpleConfigOptions     `mapstructure:"options" yaml:"options,omitempty" json:"options,omitempty"`
 	Env             []EnvVarWithNodeFilters `mapstructure:"env" yaml:"env,omitempty" json:"env,omitempty"`
 	Registries      SimpleConfigRegistries  `mapstructure:"registries" yaml:"registries,omitempty" json:"registries,omitempty"`
-	ExtraHosts      []string                `mapstructure:"extraHosts" yaml:"extraHosts,omitempty" json:"extraHosts,omitempty"`
+	HostAliases     []types.HostAlias       `mapstructure:"hostAliases" yaml:"hostAliases,omitempty" json:"hostAliases,omitempty"`
 }
 
 type SimpleConfigIntermediateV1alpha2 struct {

pkg/types/types.go

@@ -101,6 +101,11 @@ var DoNotCopyServerFlags = []string{
 	"--cluster-init",
 }
 
+type HostAlias struct {
+	IP        string   `mapstructure:"ip" yaml:"ip" json:"ip"`
+	Hostnames []string `mapstructure:"hostnames" yaml:"hostnames" json:"hostnames"`
+}
+
 // ClusterCreateOpts describe a set of options one can set when creating a cluster
 type ClusterCreateOpts struct {
 	DisableImageVolume  bool              `yaml:"disableImageVolume" json:"disableImageVolume,omitempty"`
@@ -113,7 +118,7 @@ type ClusterCreateOpts struct {
 	NodeHooks           []NodeHook        `yaml:"nodeHooks,omitempty" json:"nodeHooks,omitempty"`
 	GlobalLabels        map[string]string `yaml:"globalLabels,omitempty" json:"globalLabels,omitempty"`
 	GlobalEnv           []string          `yaml:"globalEnv,omitempty" json:"globalEnv,omitempty"`
-	ExtraHosts          []string          `yaml:"extraHosts,omitempty" json:"extraHosts,omitempty"`
+	HostAliases         []HostAlias       `yaml:"hostAliases,omitempty" json:"hostAliases,omitempty"`
 	Registries          struct {
 		Create *Registry     `yaml:"create,omitempty" json:"create,omitempty"`
 		Use    []*Registry   `yaml:"use,omitempty" json:"use,omitempty"`
@@ -289,7 +294,7 @@ type Node struct {
 	RuntimeLabels map[string]string `yaml:"runtimeLabels" json:"runtimeLabels,omitempty"`
 	K3sNodeLabels map[string]string `yaml:"k3sNodeLabels" json:"k3sNodeLabels,omitempty"`
 	Networks      []string          // filled automatically
-	ExtraHosts    []string          // filled automatically
+	ExtraHosts    []string          // filled automatically (docker specific?)
 	ServerOpts    ServerOpts        `yaml:"serverOpts" json:"serverOpts,omitempty"`
 	AgentOpts     AgentOpts         `yaml:"agentOpts" json:"agentOpts,omitempty"`
 	GPURequest    string            // filled automatically