dm: fix empty config cause dm-master panic

dm/dm/config/task.go

@@ -689,10 +689,11 @@ func (c *TaskConfig) adjust() error {
 			rule, ok := c.Mydumpers[inst.MydumperConfigName]
 			if !ok {
 				return terror.ErrConfigMydumperCfgNotFound.Generate(i, inst.MydumperConfigName)
+			} else if rule != nil {
+				globalConfigReferCount[configRefPrefixes[mydumperIdx]+inst.MydumperConfigName]++
+				inst.Mydumper = new(MydumperConfig)
+				*inst.Mydumper = *rule // ref mydumper config
 			}
-			globalConfigReferCount[configRefPrefixes[mydumperIdx]+inst.MydumperConfigName]++
-			inst.Mydumper = new(MydumperConfig)
-			*inst.Mydumper = *rule // ref mydumper config
 		}
 		if inst.Mydumper == nil {
 			if len(c.Mydumpers) != 0 {
@@ -717,10 +718,11 @@ func (c *TaskConfig) adjust() error {
 			rule, ok := c.Loaders[inst.LoaderConfigName]
 			if !ok {
 				return terror.ErrConfigLoaderCfgNotFound.Generate(i, inst.LoaderConfigName)
+			} else if rule != nil {
+				globalConfigReferCount[configRefPrefixes[loaderIdx]+inst.LoaderConfigName]++
+				inst.Loader = new(LoaderConfig)
+				*inst.Loader = *rule // ref loader config
 			}
-			globalConfigReferCount[configRefPrefixes[loaderIdx]+inst.LoaderConfigName]++
-			inst.Loader = new(LoaderConfig)
-			*inst.Loader = *rule // ref loader config
 		}
 		if inst.Loader == nil {
 			if len(c.Loaders) != 0 {
@@ -737,10 +739,11 @@ func (c *TaskConfig) adjust() error {
 			rule, ok := c.Syncers[inst.SyncerConfigName]
 			if !ok {
 				return terror.ErrConfigSyncerCfgNotFound.Generate(i, inst.SyncerConfigName)
+			} else if rule != nil {
+				globalConfigReferCount[configRefPrefixes[syncerIdx]+inst.SyncerConfigName]++
+				inst.Syncer = new(SyncerConfig)
+				*inst.Syncer = *rule // ref syncer config
 			}
-			globalConfigReferCount[configRefPrefixes[syncerIdx]+inst.SyncerConfigName]++
-			inst.Syncer = new(SyncerConfig)
-			*inst.Syncer = *rule // ref syncer config
 		}
 		if inst.Syncer == nil {
 			if len(c.Syncers) != 0 {
@@ -816,10 +819,7 @@ func (c *TaskConfig) adjust() error {
 			unusedConfigs = append(unusedConfigs, mydumper)
 		}
 	}
-	for loader, cfg := range c.Loaders {
-		if err1 := cfg.adjust(); err1 != nil {
-			return err1
-		}
+	for loader := range c.Loaders {
 		if globalConfigReferCount[configRefPrefixes[loaderIdx]+loader] == 0 {
 			unusedConfigs = append(unusedConfigs, loader)
 		}
@@ -844,6 +844,13 @@ func (c *TaskConfig) adjust() error {
 		sort.Strings(unusedConfigs)
 		return terror.ErrConfigGlobalConfigsUnused.Generate(unusedConfigs)
 	}
+
+	for _, cfg := range c.Loaders {
+		if err1 := cfg.adjust(); err1 != nil {
+			return err1
+		}
+	}
+
 	// we postpone default time_zone init in each unit so we won't change the config value in task/sub_task config
 	if c.Timezone != "" {
 		if _, err := utils.ParseTimeZone(c.Timezone); err != nil {

dm/tests/dmctl_basic/check_list/start_task.sh

@@ -26,3 +26,31 @@ function start_task_not_pass_with_message() {
 		"start-task $task_conf" \
 		"$2" 1
 }
+
+function start_task_empty_config() {
+	start_task_empty_dump_config $1
+	start_task_empty_load_config $1
+	start_task_empty_sync_config $1
+}
+
+function start_task_empty_dump_config() {
+	sed "/threads/d" $1 >/tmp/empty-dump.yaml
+	run_dm_ctl $WORK_DIR "127.0.0.1:$MASTER_PORT" \
+		"start-task /tmp/empty-dump.yaml" \
+		"The configurations as following .* are set in global configuration but instances don't use them" 1
+}
+
+function start_task_empty_load_config() {
+	sed "/pool-size/d" $1 >/tmp/empty-load.yaml
+	cat /tmp/empty-load.yaml
+	run_dm_ctl $WORK_DIR "127.0.0.1:$MASTER_PORT" \
+		"start-task /tmp/empty-load.yaml" \
+		"The configurations as following .* are set in global configuration but instances don't use them" 1
+}
+
+function start_task_empty_sync_config() {
+	sed "/worker-count/d" $1 >/tmp/empty-sync.yaml
+	run_dm_ctl $WORK_DIR "127.0.0.1:$MASTER_PORT" \
+		"start-task /tmp/empty-sync.yaml" \
+		"The configurations as following .* are set in global configuration but instances don't use them" 1
+}

dm/tests/dmctl_basic/conf/empty-unit-task.yaml

@@ -0,0 +1,27 @@
+---
+name: test
+task-mode: all
+
+target-database:
+  host: "127.0.0.1"
+  port: 4000
+  user: "root"
+  password: ""
+
+mysql-instances:
+  - source-id: "mysql-replica-01"
+    mydumper-config-name: "global"
+    loader-config-name: "global"
+    syncer-config-name: "global"
+
+mydumpers:
+  global:
+    threads: 4
+
+loaders:
+  global:
+    pool-size: 16
+
+syncers:
+  global:
+    worker-count: 32

dm/tests/dmctl_basic/run.sh

@@ -297,6 +297,9 @@ function run() {
 		"stop-task $cur/conf/only_warning.yaml" \
 		"\"result\": true" 2
 
+	echo "start task with empty unit config"
+	start_task_empty_config $cur/conf/empty-unit-task.yaml
+
 	cp $cur/conf/dm-task.yaml $WORK_DIR/dm-task-error-database-config.yaml
 	sed -i "s/password: \"\"/password: \"wrond password\"/g" $WORK_DIR/dm-task-error-database-config.yaml
 	check_task_error_database_config $WORK_DIR/dm-task-error-database-config.yaml