Migrate volume commands to cobra.

Signed-off-by: Daniel Nephin <dnephin@docker.com>

cobraadaptor/adaptor.go

@@ -0,0 +1,83 @@
+package cobraadaptor
+
+import (
+	"github.com/docker/docker/api/client"
+	"github.com/docker/docker/api/client/volume"
+	"github.com/docker/docker/cli"
+	cliflags "github.com/docker/docker/cli/flags"
+	"github.com/docker/docker/pkg/term"
+	"github.com/spf13/cobra"
+)
+
+// CobraAdaptor is an adaptor for supporting spf13/cobra commands in the
+// docker/cli framework
+type CobraAdaptor struct {
+	rootCmd   *cobra.Command
+	dockerCli *client.DockerCli
+}
+
+// NewCobraAdaptor returns a new handler
+func NewCobraAdaptor(clientFlags *cliflags.ClientFlags) CobraAdaptor {
+	var rootCmd = &cobra.Command{
+		Use: "docker",
+	}
+	rootCmd.SetUsageTemplate(usageTemplate)
+
+	stdin, stdout, stderr := term.StdStreams()
+	dockerCli := client.NewDockerCli(stdin, stdout, stderr, clientFlags)
+
+	rootCmd.AddCommand(
+		volume.NewVolumeCommand(dockerCli),
+	)
+	return CobraAdaptor{
+		rootCmd:   rootCmd,
+		dockerCli: dockerCli,
+	}
+}
+
+// Usage returns the list of commands and their short usage string for
+// all top level cobra commands.
+func (c CobraAdaptor) Usage() []cli.Command {
+	cmds := []cli.Command{}
+	for _, cmd := range c.rootCmd.Commands() {
+		cmds = append(cmds, cli.Command{Name: cmd.Use, Description: cmd.Short})
+	}
+	return cmds
+}
+
+func (c CobraAdaptor) run(cmd string, args []string) error {
+	c.dockerCli.Initialize()
+	// Prepend the command name to support normal cobra command delegation
+	c.rootCmd.SetArgs(append([]string{cmd}, args...))
+	return c.rootCmd.Execute()
+}
+
+// Command returns a cli command handler if one exists
+func (c CobraAdaptor) Command(name string) func(...string) error {
+	for _, cmd := range c.rootCmd.Commands() {
+		if cmd.Name() == name {
+			return func(args ...string) error {
+				return c.run(name, args)
+			}
+		}
+	}
+	return nil
+}
+
+var usageTemplate = `Usage:  {{if .Runnable}}{{if .HasFlags}}{{appendIfNotPresent .UseLine "[OPTIONS]"}}{{else}}{{.UseLine}}{{end}}{{end}}{{if .HasSubCommands}}{{ .CommandPath}} COMMAND {{end}}{{if gt .Aliases 0}}
+
+Aliases:
+  {{.NameAndAliases}}
+{{end}}{{if .HasExample}}
+
+Examples:
+{{ .Example }}{{end}}{{ if .HasLocalFlags}}
+
+Options:
+{{.LocalFlags.FlagUsages | trimRightSpace}}{{end}}{{ if .HasAvailableSubCommands}}
+
+Commands:{{range .Commands}}{{if .IsAvailableCommand}}
+  {{rpad .Name .NamePadding }} {{.Short}}{{end}}{{end}}{{end}}{{ if .HasSubCommands }}
+
+Run '{{.CommandPath}} COMMAND --help' for more information on a command.{{end}}
+`

required.go

@@ -0,0 +1,23 @@
+package cli
+
+import (
+	"fmt"
+
+	"github.com/spf13/cobra"
+)
+
+// MinRequiredArgs checks if the minimum number of args exists, and returns an
+// error if they do not.
+func MinRequiredArgs(args []string, min int, cmd *cobra.Command) error {
+	if len(args) >= min {
+		return nil
+	}
+
+	return fmt.Errorf(
+		"\"%s\" requires at least %d argument(s).\n\nUsage:  %s\n\n%s",
+		cmd.CommandPath(),
+		min,
+		cmd.UseLine(),
+		cmd.Short,
+	)
+}