config: add config unset command to remove options from a remote - fixes #9541

Previously the only way to remove an option from a remote was to set it
to an empty string, which is not the same as deleting it - a present but
empty value overrides the option's default whereas a deleted key
restores it. Editing the file by hand isn't an option for an encrypted
config either.

This adds a "config unset" command and a "config/unset" rc endpoint to
remove one or more keys from an existing remote.

cmd/config/config.go

@@ -32,6 +32,7 @@ func init() {
 	configCommand.AddCommand(configCreateCommand)
 	configCommand.AddCommand(configUpdateCommand)
 	configCommand.AddCommand(configDeleteCommand)
+	configCommand.AddCommand(configUnsetCommand)
 	configCommand.AddCommand(configPasswordCommand)
 	configCommand.AddCommand(configReconnectCommand)
 	configCommand.AddCommand(configDisconnectCommand)
@@ -388,6 +389,40 @@ var configDeleteCommand = &cobra.Command{
 	},
 }
 
+var configUnsetCommand = &cobra.Command{
+	Use:   "unset name [key]+",
+	Short: `Unset options in an existing remote.`,
+	Long: strings.ReplaceAll(`Remove one or more options from an existing remote. The options to
+remove should be passed in as a list of key names.
+
+For example, to remove the |client_id| and |client_secret| options from
+a remote of name myremote you would do:
+
+|||sh
+rclone config unset myremote client_id client_secret
+|||
+
+This removes the keys from the config file entirely, which is different
+from setting them to an empty string with |config update|. Removing a
+key restores rclone's default behaviour for that option, whereas setting
+it to an empty string overrides the default with an empty value.
+
+You can't unset the |type| of a remote - use |config delete| to remove
+the whole remote instead.`, "|", "`"),
+	Annotations: map[string]string{
+		"versionIntroduced": "v1.75",
+	},
+	RunE: func(command *cobra.Command, args []string) error {
+		cmd.CheckArgs(2, 256, command, args)
+		_, err := config.UnsetRemote(args[0], args[1:]...)
+		if err != nil {
+			return err
+		}
+		config.ShowRemote(args[0])
+		return nil
+	},
+}
+
 var configPasswordCommand = &cobra.Command{
 	Use:   "password name [key value]+",
 	Short: `Update password in an existing remote.`,

fs/config/config.go

@@ -661,6 +661,34 @@ func PasswordRemote(ctx context.Context, name string, keyValues rc.Params) error
 	return err
 }
 
+// UnsetRemote removes the named keys from the remote of name.
+//
+// It returns the keys that were actually removed - keys that didn't
+// exist are silently ignored. It returns an error if the remote
+// doesn't exist or if an attempt is made to unset the "type" key.
+func UnsetRemote(name string, keys ...string) (removed []string, err error) {
+	err = fspath.CheckConfigName(name)
+	if err != nil {
+		return nil, err
+	}
+	if GetValue(name, "type") == "" {
+		return nil, fmt.Errorf("remote %q doesn't exist", name)
+	}
+	for _, key := range keys {
+		if key == "type" {
+			return nil, errors.New(`can't unset the "type" of a remote - use "config delete" to remove the whole remote`)
+		}
+	}
+	for _, key := range keys {
+		if FileDeleteKey(name, key) {
+			removed = append(removed, key)
+		}
+	}
+	SaveConfig()
+	cache.ClearConfig(name) // remove any remotes based on this config from the cache
+	return removed, nil
+}
+
 // JSONListProviders prints all the providers and options in JSON format
 func JSONListProviders() error {
 	b, err := json.MarshalIndent(fs.Registry, "", "    ")

fs/config/rc.go

@@ -256,6 +256,44 @@ func rcDelete(ctx context.Context, in rc.Params) (out rc.Params, err error) {
 	return nil, nil
 }
 
+func init() {
+	rc.Add(rc.Call{
+		Path:  "config/unset",
+		Fn:    rcUnset,
+		Title: "Unset keys in a remote in the config file.",
+		Help: `
+Parameters:
+
+- name - name of remote
+- keys - a list of key names to remove
+
+Returns:
+
+- removed - a list of the keys that were actually removed
+
+See the [config unset](/commands/rclone_config_unset/) command for more information on the above.
+`,
+	})
+}
+
+// Remove keys from a remote in the config file
+func rcUnset(ctx context.Context, in rc.Params) (out rc.Params, err error) {
+	name, err := in.GetString("name")
+	if err != nil {
+		return nil, err
+	}
+	var keys []string
+	err = in.GetStruct("keys", &keys)
+	if err != nil {
+		return nil, err
+	}
+	removed, err := UnsetRemote(name, keys...)
+	if err != nil {
+		return nil, err
+	}
+	return rc.Params{"removed": removed}, nil
+}
+
 func init() {
 	rc.Add(rc.Call{
 		Path:  "config/setpath",

fs/config/rc_test.go

@@ -134,6 +134,29 @@ func TestRc(t *testing.T) {
 		assert.Equal(t, pw2, obscure.MustReveal(config.GetValue(testName, "test_key2")))
 	})
 
+	t.Run("Unset", func(t *testing.T) {
+		config.FileSetValue(testName, "unset_key", "to be removed")
+		call := rc.Calls.Get("config/unset")
+		assert.NotNil(t, call)
+		in := rc.Params{
+			"name": testName,
+			"keys": []string{"unset_key", "missing_key"},
+		}
+		out, err := call.Fn(context.Background(), in)
+		require.NoError(t, err)
+		require.NotNil(t, out)
+
+		// Only the key that existed is reported as removed
+		var removed []string
+		err = out.GetStruct("removed", &removed)
+		require.NoError(t, err)
+		assert.Equal(t, []string{"unset_key"}, removed)
+
+		// The key is gone from the config file entirely
+		_, found := config.FileGetValue(testName, "unset_key")
+		assert.False(t, found)
+	})
+
 	// Delete the test remote
 	call = rc.Calls.Get("config/delete")
 	assert.NotNil(t, call)

fs/config/ui_test.go

@@ -250,6 +250,40 @@ func TestCreateUpdatePasswordRemote(t *testing.T) {
 	}
 }
 
+func TestUnsetRemote(t *testing.T) {
+	ctx := context.Background()
+	defer testConfigFile(t, simpleOptions, "unset.conf")()
+
+	_, err := config.CreateRemote(ctx, "test", "config_test_remote", rc.Params{
+		"bool":  true,
+		"spare": "spare",
+	}, config.UpdateRemoteOpt{})
+	require.NoError(t, err)
+	_, found := config.FileGetValue("test", "spare")
+	require.True(t, found)
+
+	// Unsetting a missing remote is an error
+	_, err = config.UnsetRemote("notfound", "spare")
+	assert.Error(t, err)
+
+	// Unsetting the type is an error and removes nothing
+	_, err = config.UnsetRemote("test", "type")
+	assert.Error(t, err)
+	assert.Equal(t, "config_test_remote", config.GetValue("test", "type"))
+
+	// Unset an existing key and a missing one - only the existing one
+	// is reported as removed
+	removed, err := config.UnsetRemote("test", "spare", "missing")
+	require.NoError(t, err)
+	assert.Equal(t, []string{"spare"}, removed)
+
+	// The key is gone entirely, not just set to empty
+	_, found = config.FileGetValue("test", "spare")
+	assert.False(t, found)
+	// Other keys are untouched
+	assert.Equal(t, "true", config.GetValue("test", "bool"))
+}
+
 func TestDefaultRequired(t *testing.T) {
 	// By default options are optional (sic), regardless if a default value is defined.
 	// Setting Required=true means empty string is no longer allowed, except when