Update CLI docs and add opts/config.go

Signed-off-by: Aaron Lehmann <aaron.lehmann@docker.com>

opts/config.go

@@ -0,0 +1,98 @@
+package opts
+
+import (
+	"encoding/csv"
+	"fmt"
+	"os"
+	"strconv"
+	"strings"
+
+	swarmtypes "github.com/docker/docker/api/types/swarm"
+)
+
+// ConfigOpt is a Value type for parsing configs
+type ConfigOpt struct {
+	values []*swarmtypes.ConfigReference
+}
+
+// Set a new config value
+func (o *ConfigOpt) Set(value string) error {
+	csvReader := csv.NewReader(strings.NewReader(value))
+	fields, err := csvReader.Read()
+	if err != nil {
+		return err
+	}
+
+	options := &swarmtypes.ConfigReference{
+		File: &swarmtypes.ConfigReferenceFileTarget{
+			UID:  "0",
+			GID:  "0",
+			Mode: 0444,
+		},
+	}
+
+	// support a simple syntax of --config foo
+	if len(fields) == 1 {
+		options.File.Name = fields[0]
+		options.ConfigName = fields[0]
+		o.values = append(o.values, options)
+		return nil
+	}
+
+	for _, field := range fields {
+		parts := strings.SplitN(field, "=", 2)
+		key := strings.ToLower(parts[0])
+
+		if len(parts) != 2 {
+			return fmt.Errorf("invalid field '%s' must be a key=value pair", field)
+		}
+
+		value := parts[1]
+		switch key {
+		case "source", "src":
+			options.ConfigName = value
+		case "target":
+			options.File.Name = value
+		case "uid":
+			options.File.UID = value
+		case "gid":
+			options.File.GID = value
+		case "mode":
+			m, err := strconv.ParseUint(value, 0, 32)
+			if err != nil {
+				return fmt.Errorf("invalid mode specified: %v", err)
+			}
+
+			options.File.Mode = os.FileMode(m)
+		default:
+			return fmt.Errorf("invalid field in config request: %s", key)
+		}
+	}
+
+	if options.ConfigName == "" {
+		return fmt.Errorf("source is required")
+	}
+
+	o.values = append(o.values, options)
+	return nil
+}
+
+// Type returns the type of this option
+func (o *ConfigOpt) Type() string {
+	return "config"
+}
+
+// String returns a string repr of this option
+func (o *ConfigOpt) String() string {
+	configs := []string{}
+	for _, config := range o.values {
+		repr := fmt.Sprintf("%s -> %s", config.ConfigName, config.File.Name)
+		configs = append(configs, repr)
+	}
+	return strings.Join(configs, ", ")
+}
+
+// Value returns the config requests
+func (o *ConfigOpt) Value() []*swarmtypes.ConfigReference {
+	return o.values
+}