Add support for the --publish option for create subcommand

Inspired by the docker CLI, --publish take same input as docker CLI and
provides similar functions. For the k3s cluster server node, it behaves
the same as docker cli; it exports the k3d server ports to the host
ports.

Handling for worker nodes will be added in the subsequent patches.

This option can be used mutiple times for exposing more ports.

--add-port is an alias to this option.

cli/commands.go

@@ -71,6 +71,11 @@ func CreateCluster(c *cli.Context) error {
 		k3sServerArgs = append(k3sServerArgs, c.StringSlice("server-arg")...)
 	}
 
+	publishedPorts, err := createPublishedPorts(c.StringSlice("publish"))
+	if (err != nil) {
+		log.Fatalf("ERROR: failed to parse the publish parameter.\n%+v", err)
+	}
+
 	// create the server
 	log.Printf("Creating cluster [%s]", c.String("name"))
 	dockerID, err := createServer(
@@ -81,6 +86,7 @@ func CreateCluster(c *cli.Context) error {
 		env,
 		c.String("name"),
 		strings.Split(c.String("volume"), ","),
+		publishedPorts,
 	)
 	if err != nil {
 		log.Fatalf("ERROR: failed to create cluster\n%+v", err)

cli/container.go

@@ -138,7 +138,8 @@ func startContainer(verbose bool, config *container.Config, hostConfig *containe
 	return resp.ID, nil
 }
 
-func createServer(verbose bool, image string, port string, args []string, env []string, name string, volumes []string) (string, error) {
+func createServer(verbose bool, image string, port string, args []string, env []string,
+                  name string, volumes []string, pPorts *PublishedPorts) (string, error) {
 	log.Printf("Creating server using %s...\n", image)
 
 	containerLabels := make(map[string]string)
@@ -149,17 +150,14 @@ func createServer(verbose bool, image string, port string, args []string, env []
 
 	containerName := fmt.Sprintf("k3d-%s-server", name)
 
-	containerPort := nat.Port(fmt.Sprintf("%s/tcp", port))
+	apiPortSpec := fmt.Sprintf("0.0.0.0:%s:%s/tcp", port, port)
+	serverPublishedPorts, err := pPorts.AddPort(apiPortSpec)
+	if (err != nil) {
+		log.Fatalf("Error: failed to parse API port spec %s \n%+v", apiPortSpec, err)
+	}
 
 	hostConfig := &container.HostConfig{
-		PortBindings: nat.PortMap{
-			containerPort: []nat.PortBinding{
-				{
-					HostIP:   "0.0.0.0",
-					HostPort: port,
-				},
-			},
-		},
+		PortBindings: serverPublishedPorts.PortBindings,
 		Privileged: true,
 	}
 
@@ -179,9 +177,7 @@ func createServer(verbose bool, image string, port string, args []string, env []
 		Hostname: containerName,
 		Image:    image,
 		Cmd:      append([]string{"server"}, args...),
-		ExposedPorts: nat.PortSet{
-			containerPort: struct{}{},
-		},
+		ExposedPorts: serverPublishedPorts.ExposedPorts,
 		Env:    env,
 		Labels: containerLabels,
 	}

main.go

@@ -55,6 +55,10 @@ func main() {
 					Name:  "volume, v",
 					Usage: "Mount one or more volumes into every node of the cluster (Docker notation: `source:destination[,source:destination]`)",
 				},
+				cli.StringSliceFlag{
+					Name:  "publish, add-port",
+					Usage: "publish k3s node ports to the host (Docker notation: `ip:public:private/proto`, use multiple options to expose more ports)",
+				},
 				cli.StringFlag{
 					Name:  "version",
 					Value: version.GetK3sVersion(),