config set: allow arbitrary json input

This commit allows arbitrary json input to set.
It also tests this with sharness.

core/commands/config.go

@@ -59,6 +59,7 @@ Set the value of the 'datastore.path' key:
 	},
 	Options: []cmds.Option{
 		cmds.BoolOption("bool", "Set a boolean value"),
+		cmds.BoolOption("json", "Parse stringified JSON"),
 	},
 	Run: func(req cmds.Request, res cmds.Response) {
 		args := req.Arguments()
@@ -74,7 +75,17 @@ Set the value of the 'datastore.path' key:
 		var output *ConfigField
 		if len(args) == 2 {
 			value := args[1]
-			if isbool, _, _ := req.Option("bool").Bool(); isbool {
+
+			if parseJson, _, _ := req.Option("json").Bool(); parseJson {
+				var jsonVal interface{}
+				if err := json.Unmarshal([]byte(value), &jsonVal); err != nil {
+					err = fmt.Errorf("failed to unmarshal json. %s", err)
+					res.SetError(err, cmds.ErrNormal)
+					return
+				}
+
+				output, err = setConfig(r, key, jsonVal)
+			} else if isbool, _, _ := req.Option("bool").Bool(); isbool {
 				output, err = setConfig(r, key, value == "true")
 			} else {
 				output, err = setConfig(r, key, value)
@@ -217,7 +228,7 @@ func getConfig(r repo.Repo, key string) (*ConfigField, error) {
 func setConfig(r repo.Repo, key string, value interface{}) (*ConfigField, error) {
 	err := r.SetConfigKey(key, value)
 	if err != nil {
-		return nil, fmt.Errorf("Failed to set config value: %s", err)
+		return nil, fmt.Errorf("Failed to set config value: %s (maybe use --json?)", err)
 	}
 	return getConfig(r, key)
 }

test/sharness/t0021-config.sh

@@ -36,6 +36,17 @@ test_config_cmd_set() {
   '
 }
 
+# this is a bit brittle. the problem is we need to test
+# with something that will be forced to unmarshal as a struct.
+# (i.e. just setting 'ipfs config --json foo "[1, 2, 3]"') may
+# set it as astring instead of proper json. We leverage the
+# unmarshalling that has to happen.
+CONFIG_SET_JSON_TEST='{
+  "MDNS": {
+    "Enabled": true,
+    "Interval": 10
+  }
+}'
 
 test_config_cmd() {
   test_config_cmd_set "beep" "boop"
@@ -43,6 +54,9 @@ test_config_cmd() {
   test_config_cmd_set "beep1" "boop2"
   test_config_cmd_set "--bool" "beep2" "true"
   test_config_cmd_set "--bool" "beep2" "false"
+  test_config_cmd_set "--json" "beep3" "true"
+  test_config_cmd_set "--json" "beep3" "false"
+  test_config_cmd_set "--json" "Discovery" "$CONFIG_SET_JSON_TEST"
 
 }