[MM-12360] Created CLI command "config get" (#9534) (#9558)

* Added the get command to get the value of a config setting.

* Depending on the config setting it can work on any depth of the
setting.

* Added test for the get command.

* Add print tabs

* Remove excess else statements

* Return with the value and remove named return variable

* Refactor the printMap function and return a string, remove side effects

* Improve the error message, use the name argument

* Use app.Config() to create our config object

* Remove reading the file, make helper functions return string and perform printing inside the command

* Remove the tab printing

* Add extra quotes on the output

* Remove extra code for checking arguments and replaced it with cobra.ExactArgs(1)

* Remove buffer from printConfigValues

* Add some tests to check the output of the command

* Write test for the function 'structToMap' and test for complext nested structs

* Write test for the function 'configToMap' and test for complext nested structs

* Write test for the function 'printMap' and test for complext maps as input

* Write test for the function 'printConfigValues' and test for complext maps as input

* Remove commented code

* Update the description of the  command

2 files changed, 507 insertions, 0 deletions

diff --git a/cmd/mattermost/commands/config.go b/cmd/mattermost/commands/config.go
index b8630b82f..47dd61458 100644
--- a/cmd/mattermost/commands/config.go
+++ b/cmd/mattermost/commands/config.go
@@ -4,12 +4,17 @@
 package commands
 
 import (
+	"bytes"
 	"encoding/json"
+	"fmt"
 	"os"
+	"reflect"
+	"strings"
 
 	"github.com/pkg/errors"
 	"github.com/spf13/cobra"
 
+	"github.com/mattermost/mattermost-server/mlog"
 	"github.com/mattermost/mattermost-server/model"
 	"github.com/mattermost/mattermost-server/utils"
 )
@@ -36,12 +41,22 @@ var ConfigSubpathCmd = &cobra.Command{
 	RunE: configSubpathCmdF,
 }
 
+var ConfigGetCmd = &cobra.Command{
+	Use:     "get",
+	Short:   "Get config setting",
+	Long:    "Gets the value of a config setting by its name in dot notation.",
+	Example: `config get SqlSettings.DriverName`,
+	Args:    cobra.ExactArgs(1),
+	RunE:    configGetCmdF,
+}
+
 func init() {
 	ConfigSubpathCmd.Flags().String("path", "", "Optional subpath; defaults to value in SiteURL")
 
 	ConfigCmd.AddCommand(
 		ValidateConfigCmd,
 		ConfigSubpathCmd,
+		ConfigGetCmd,
 	)
 	RootCmd.AddCommand(ConfigCmd)
 }
@@ -102,3 +117,120 @@ func configSubpathCmdF(command *cobra.Command, args []string) error {
 
 	return nil
 }
+
+func configGetCmdF(command *cobra.Command, args []string) error {
+	app, err := InitDBCommandContextCobra(command)
+	if err != nil {
+		return err
+	}
+	defer app.Shutdown()
+
+	// create the model for config
+	// Note: app.Config() returns a pointer, make appropriate changes
+	config := app.Config()
+
+	// get the print config setting and any error if there is
+	out, err := printConfigValues(configToMap(*config), strings.Split(args[0], "."), args[0])
+	if err != nil {
+		return err
+	}
+
+	fmt.Printf("%s", out)
+
+	return nil
+}
+
+// printConfigValues function prints out the value of the configSettings working recursively or
+// gives an error if config setting is not in the file.
+func printConfigValues(configMap map[string]interface{}, configSetting []string, name string) (string, error) {
+
+	res, ok := configMap[configSetting[0]]
+	if !ok {
+		return "", fmt.Errorf("%s configuration setting is not in the file", name)
+	}
+	value := reflect.ValueOf(res)
+	switch value.Kind() {
+	case reflect.Map:
+		if len(configSetting) == 1 {
+			return printMap(value, 0), nil
+		}
+		return printConfigValues(res.(map[string]interface{}), configSetting[1:], name)
+	default:
+		if len(configSetting) == 1 {
+			return fmt.Sprintf("%s: \"%v\"\n", name, res), nil
+		}
+		return "", fmt.Errorf("%s configuration setting is not in the file", name)
+	}
+}
+
+// printMap takes a reflect.Value and return a string, recursively if its a map with the given tab settings.
+func printMap(value reflect.Value, tabVal int) string {
+
+	// our output buffer
+	out := &bytes.Buffer{}
+
+	for _, key := range value.MapKeys() {
+		val := value.MapIndex(key)
+		if newVal, ok := val.Interface().(map[string]interface{}); !ok {
+			fmt.Fprintf(out, "%s", strings.Repeat("\t", tabVal))
+			fmt.Fprintf(out, "%v: \"%v\"\n", key.Interface(), val.Interface())
+		} else {
+			fmt.Fprintf(out, "%s", strings.Repeat("\t", tabVal))
+			fmt.Fprintf(out, "%v:\n", key.Interface())
+			// going one level in, increase the tab
+			tabVal++
+			fmt.Fprintf(out, "%s", printMap(reflect.ValueOf(newVal), tabVal))
+			// coming back one level, decrease the tab
+			tabVal--
+		}
+	}
+
+	return out.String()
+
+}
+
+// configToMap converts our config into a map
+func configToMap(s interface{}) map[string]interface{} {
+	return structToMap(s)
+}
+
+// structToMap converts a struct into a map
+func structToMap(t interface{}) map[string]interface{} {
+	defer func() {
+		if r := recover(); r != nil {
+			mlog.Error(fmt.Sprintf("Panicked in structToMap. This should never happen. %v", r))
+		}
+	}()
+
+	val := reflect.ValueOf(t)
+
+	if val.Kind() != reflect.Struct {
+		return nil
+	}
+
+	out := map[string]interface{}{}
+
+	for i := 0; i < val.NumField(); i++ {
+		field := val.Field(i)
+
+		var value interface{}
+
+		switch field.Kind() {
+		case reflect.Struct:
+			value = structToMap(field.Interface())
+		case reflect.Ptr:
+			indirectType := field.Elem()
+
+			if indirectType.Kind() == reflect.Struct {
+				value = structToMap(indirectType.Interface())
+			} else {
+				value = indirectType.Interface()
+			}
+		default:
+			value = field.Interface()
+		}
+
+		out[val.Type().Field(i).Name] = value
+	}
+	return out
+}
diff --git a/cmd/mattermost/commands/config_test.go b/cmd/mattermost/commands/config_test.go
index fcc35bd02..a68818201 100644
--- a/cmd/mattermost/commands/config_test.go
+++ b/cmd/mattermost/commands/config_test.go
@@ -7,6 +7,9 @@ import (
 	"io/ioutil"
 	"os"
 	"path/filepath"
+	"reflect"
+	"sort"
+	"strings"
 	"testing"
 
 	"github.com/stretchr/testify/assert"
@@ -15,6 +18,42 @@ import (
 	"github.com/mattermost/mattermost-server/model"
 )
 
+type TestConfig struct {
+	TestServiceSettings       TestServiceSettings
+	TestTeamSettings          TestTeamSettings
+	TestClientRequirements    TestClientRequirements
+	TestMessageExportSettings TestMessageExportSettings
+}
+
+type TestMessageExportSettings struct {
+	Enableexport            bool
+	Exportformat            string
+	TestGlobalRelaySettings TestGlobalRelaySettings
+}
+
+type TestGlobalRelaySettings struct {
+	Customertype string
+	Smtpusername string
+	Smtppassword string
+}
+
+type TestServiceSettings struct {
+	Siteurl               string
+	Websocketurl          string
+	Licensedfieldlocation string
+}
+
+type TestTeamSettings struct {
+	Sitename       string
+	Maxuserperteam int
+}
+
+type TestClientRequirements struct {
+	Androidlatestversion string
+	Androidminversion    string
+	Desktoplatestversion string
+}
+
 func TestConfigValidate(t *testing.T) {
 	dir, err := ioutil.TempDir("", "")
 	require.NoError(t, err)
@@ -28,3 +67,339 @@ func TestConfigValidate(t *testing.T) {
 	assert.Error(t, RunCommand(t, "--config", "foo.json", "config", "validate"))
 	assert.NoError(t, RunCommand(t, "--config", path, "config", "validate"))
 }
+
+func TestConfigGet(t *testing.T) {
+	// Error when no arguments are given
+	assert.Error(t, RunCommand(t, "config", "get"))
+
+	// Error when more than one config settings are given
+	assert.Error(t, RunCommand(t, "config", "get", "abc", "def"))
+
+	// Error when a config setting which is not in the config.json is given
+	assert.Error(t, RunCommand(t, "config", "get", "abc"))
+
+	// No Error when a config setting which is  in the config.json is given
+	assert.NoError(t, RunCommand(t, "config", "get", "MessageExportSettings"))
+	assert.NoError(t, RunCommand(t, "config", "get", "MessageExportSettings.GlobalRelaySettings"))
+	assert.NoError(t, RunCommand(t, "config", "get", "MessageExportSettings.GlobalRelaySettings.CustomerType"))
+
+	// check output
+	output := CheckCommand(t, "config", "get", "MessageExportSettings")
+
+	assert.Contains(t, string(output), "EnableExport")
+	assert.Contains(t, string(output), "ExportFormat")
+	assert.Contains(t, string(output), "DailyRunTime")
+	assert.Contains(t, string(output), "ExportFromTimestamp")
+}
+
+func TestStructToMap(t *testing.T) {
+
+	cases := []struct {
+		Name     string
+		Input    interface{}
+		Expected map[string]interface{}
+	}{
+		{
+			Name: "Struct with one string field",
+			Input: struct {
+				Test string
+			}{
+				Test: "test",
+			},
+			Expected: map[string]interface{}{
+				"Test": "test",
+			},
+		},
+		{
+			Name: "String with multiple fields of different ",
+			Input: struct {
+				Test1 string
+				Test2 int
+				Test3 string
+				Test4 bool
+			}{
+				Test1: "test1",
+				Test2: 21,
+				Test3: "test2",
+				Test4: false,
+			},
+			Expected: map[string]interface{}{
+				"Test1": "test1",
+				"Test2": 21,
+				"Test3": "test2",
+				"Test4": false,
+			},
+		},
+		{
+			Name: "Nested fields",
+			Input: TestConfig{
+				TestServiceSettings{"abc", "def", "ghi"},
+				TestTeamSettings{"abc", 1},
+				TestClientRequirements{"abc", "def", "ghi"},
+				TestMessageExportSettings{true, "abc", TestGlobalRelaySettings{"abc", "def", "ghi"}},
+			},
+			Expected: map[string]interface{}{
+				"TestServiceSettings": map[string]interface{}{
+					"Siteurl":               "abc",
+					"Websocketurl":          "def",
+					"Licensedfieldlocation": "ghi",
+				},
+				"TestTeamSettings": map[string]interface{}{
+					"Sitename":       "abc",
+					"Maxuserperteam": 1,
+				},
+				"TestClientRequirements": map[string]interface{}{
+					"Androidlatestversion": "abc",
+					"Androidminversion":    "def",
+					"Desktoplatestversion": "ghi",
+				},
+				"TestMessageExportSettings": map[string]interface{}{
+					"Enableexport": true,
+					"Exportformat": "abc",
+					"TestGlobalRelaySettings": map[string]interface{}{
+						"Customertype": "abc",
+						"Smtpusername": "def",
+						"Smtppassword": "ghi",
+					},
+				},
+			},
+		},
+	}
+
+	for _, test := range cases {
+		t.Run(test.Name, func(t *testing.T) {
+			res := structToMap(test.Input)
+
+			if !reflect.DeepEqual(res, test.Expected) {
+				t.Errorf("got %v want %v ", res, test.Expected)
+			}
+		})
+	}
+
+}
+
+func TestConfigToMap(t *testing.T) {
+	// This test is almost the same as TestMapToStruct, but I have it here for the sake of completions
+	cases := []struct {
+		Name     string
+		Input    interface{}
+		Expected map[string]interface{}
+	}{
+		{
+			Name: "Struct with one string field",
+			Input: struct {
+				Test string
+			}{
+				Test: "test",
+			},
+			Expected: map[string]interface{}{
+				"Test": "test",
+			},
+		},
+		{
+			Name: "String with multiple fields of different ",
+			Input: struct {
+				Test1 string
+				Test2 int
+				Test3 string
+				Test4 bool
+			}{
+				Test1: "test1",
+				Test2: 21,
+				Test3: "test2",
+				Test4: false,
+			},
+			Expected: map[string]interface{}{
+				"Test1": "test1",
+				"Test2": 21,
+				"Test3": "test2",
+				"Test4": false,
+			},
+		},
+		{
+			Name: "Nested fields",
+			Input: TestConfig{
+				TestServiceSettings{"abc", "def", "ghi"},
+				TestTeamSettings{"abc", 1},
+				TestClientRequirements{"abc", "def", "ghi"},
+				TestMessageExportSettings{true, "abc", TestGlobalRelaySettings{"abc", "def", "ghi"}},
+			},
+			Expected: map[string]interface{}{
+				"TestServiceSettings": map[string]interface{}{
+					"Siteurl":               "abc",
+					"Websocketurl":          "def",
+					"Licensedfieldlocation": "ghi",
+				},
+				"TestTeamSettings": map[string]interface{}{
+					"Sitename":       "abc",
+					"Maxuserperteam": 1,
+				},
+				"TestClientRequirements": map[string]interface{}{
+					"Androidlatestversion": "abc",
+					"Androidminversion":    "def",
+					"Desktoplatestversion": "ghi",
+				},
+				"TestMessageExportSettings": map[string]interface{}{
+					"Enableexport": true,
+					"Exportformat": "abc",
+					"TestGlobalRelaySettings": map[string]interface{}{
+						"Customertype": "abc",
+						"Smtpusername": "def",
+						"Smtppassword": "ghi",
+					},
+				},
+			},
+		},
+	}
+
+	for _, test := range cases {
+		t.Run(test.Name, func(t *testing.T) {
+			res := configToMap(test.Input)
+
+			if !reflect.DeepEqual(res, test.Expected) {
+				t.Errorf("got %v want %v ", res, test.Expected)
+			}
+		})
+	}
+}
+
+func TestPrintMap(t *testing.T) {
+
+	inputCases := []interface{}{
+		map[string]interface{}{
+			"CustomerType": "A9",
+			"SmtpUsername": "",
+			"SmtpPassword": "",
+			"EmailAddress": "",
+		},
+		map[string]interface{}{
+			"EnableExport": false,
+			"ExportFormat": "actiance",
+			"DailyRunTime": "01:00",
+			"GlobalRelaySettings": map[string]interface{}{
+				"CustomerType": "A9",
+				"SmtpUsername": "",
+				"SmtpPassword": "",
+				"EmailAddress": "",
+			},
+		},
+	}
+
+	outputCases := []string{
+		"CustomerType: \"A9\"\nSmtpUsername: \"\"\nSmtpPassword: \"\"\nEmailAddress: \"\"\n",
+		"EnableExport: \"false\"\nExportFormat: \"actiance\"\nDailyRunTime: \"01:00\"\nGlobalRelaySettings:\n\t	CustomerType: \"A9\"\n\tSmtpUsername: \"\"\n\tSmtpPassword: \"\"\n\tEmailAddress: \"\"\n",
+	}
+
+	cases := []struct {
+		Name     string
+		Input    reflect.Value
+		Expected string
+	}{
+		{
+			Name:     "Basic print",
+			Input:    reflect.ValueOf(inputCases[0]),
+			Expected: outputCases[0],
+		},
+		{
+			Name:     "Complex print",
+			Input:    reflect.ValueOf(inputCases[1]),
+			Expected: outputCases[1],
+		},
+	}
+
+	for _, test := range cases {
+		t.Run(test.Name, func(t *testing.T) {
+			res := printMap(test.Input, 0)
+
+			// create two slice of string formed by splitting our strings on \n
+			slice1 := strings.Split(res, "\n")
+			slice2 := strings.Split(res, "\n")
+
+			sort.Strings(slice1)
+			sort.Strings(slice2)
+
+			if !reflect.DeepEqual(slice1, slice2) {
+				t.Errorf("got '%#v' want '%#v", slice1, slice2)
+			}
+
+		})
+	}
+}
+
+func TestPrintConfigValues(t *testing.T) {
+
+	outputs := []string{
+		"Siteurl: \"abc\"\nWebsocketurl: \"def\"\nLicensedfieldlocation: \"ghi\"\n",
+		"Sitename: \"abc\"\nMaxuserperteam: \"1\"\n",
+		"Androidlatestversion: \"abc\"\nAndroidminversion: \"def\"\nDesktoplatestversion: \"ghi\"\n",
+		"Enableexport: \"true\"\nExportformat: \"abc\"\nTestGlobalRelaySettings:\n\tCustomertype: \"abc\"\n\tSmtpusername: \"def\"\n\tSmtppassword: \"ghi\"\n",
+		"Customertype: \"abc\"\nSmtpusername: \"def\"\nSmtppassword: \"ghi\"\n",
+	}
+
+	commands := []string{
+		"TestServiceSettings",
+		"TestTeamSettings",
+		"TestClientRequirements",
+		"TestMessageExportSettings",
+		"TestMessageExportSettings.TestGlobalRelaySettings",
+	}
+
+	input := TestConfig{
+		TestServiceSettings{"abc", "def", "ghi"},
+		TestTeamSettings{"abc", 1},
+		TestClientRequirements{"abc", "def", "ghi"},
+		TestMessageExportSettings{true, "abc", TestGlobalRelaySettings{"abc", "def", "ghi"}},
+	}
+
+	configMap := structToMap(input)
+
+	cases := []struct {
+		Name     string
+		Command  string
+		Expected string
+	}{
+		{
+			Name:     "First test",
+			Command:  commands[0],
+			Expected: outputs[0],
+		},
+		{
+			Name:     "Second test",
+			Command:  commands[1],
+			Expected: outputs[1],
+		},
+		{
+			Name:     "third test",
+			Command:  commands[2],
+			Expected: outputs[2],
+		},
+		{
+			Name:     "fourth test",
+			Command:  commands[3],
+			Expected: outputs[3],
+		},
+		{
+			Name:     "fifth test",
+			Command:  commands[4],
+			Expected: outputs[4],
+		},
+	}
+
+	for _, test := range cases {
+		t.Run(test.Name, func(t *testing.T) {
+			res, _ := printConfigValues(configMap, strings.Split(test.Command, "."), test.Command)
+
+			// create two slice of string formed by splitting our strings on \n
+			slice1 := strings.Split(res, "\n")
+			slice2 := strings.Split(test.Expected, "\n")
+
+			sort.Strings(slice1)
+			sort.Strings(slice2)
+
+			if !reflect.DeepEqual(slice1, slice2) {
+				t.Errorf("got '%#v' want '%#v", slice1, slice2)
+			}
+		})
+	}
+
+}