Refactor config into package

* Move CLI config management into cli/config
* Add ability to save current context
* Remove ability to rename the config file as this was never used

Signed-off-by: Christopher Crone <christopher.crone@docker.com>

cli/config/flags.go

@@ -0,0 +1,60 @@
+/*
+	Copyright (c) 2020 Docker Inc.
+
+	Permission is hereby granted, free of charge, to any person
+	obtaining a copy of this software and associated documentation
+	files (the "Software"), to deal in the Software without
+	restriction, including without limitation the rights to use, copy,
+	modify, merge, publish, distribute, sublicense, and/or sell copies
+	of the Software, and to permit persons to whom the Software is
+	furnished to do so, subject to the following conditions:
+
+	The above copyright notice and this permission notice shall be
+	included in all copies or substantial portions of the Software.
+
+	THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+	EXPRESS OR IMPLIED,
+	INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+	FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+	IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+	HOLDERS BE LIABLE FOR ANY CLAIM,
+	DAMAGES OR OTHER LIABILITY,
+	WHETHER IN AN ACTION OF CONTRACT,
+	TORT OR OTHERWISE,
+	ARISING FROM, OUT OF OR IN CONNECTION WITH
+	THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+*/
+
+package config
+
+import (
+	"os"
+	"path/filepath"
+
+	"github.com/spf13/pflag"
+)
+
+const (
+	// ConfigFileName is the name of config file
+	ConfigFileName = "config.json"
+	// ConfigFileDir is the default folder where the config file is stored
+	ConfigFileDir = ".docker"
+	// ConfigFlagName is the name of the config flag
+	ConfigFlagName = "config"
+)
+
+// ConfigFlags are the global CLI flags
+// nolint stutter
+type ConfigFlags struct {
+	Config string
+}
+
+// AddConfigFlags adds persistent (global) flags
+func (c *ConfigFlags) AddConfigFlags(flags *pflag.FlagSet) {
+	flags.StringVar(&c.Config, ConfigFlagName, filepath.Join(home(), ConfigFileDir), "Location of the client config files `DIRECTORY`")
+}
+
+func home() string {
+	home, _ := os.UserHomeDir()
+	return home
+}