[WIP] config: fix panic when some field is empty

dm/config/task.go

@@ -559,7 +559,9 @@ func (c *TaskConfig) adjust() error {
 			}
 			globalConfigReferCount[configRefPrefixes[mydumperIdx]+inst.MydumperConfigName]++
 			inst.Mydumper = new(MydumperConfig)
-			*inst.Mydumper = *rule // ref mydumper config
+			if rule != nil {
+				*inst.Mydumper = *rule // ref mydumper config
+			}
 		}
 		if inst.Mydumper == nil {
 			if len(c.Mydumpers) != 0 {
@@ -587,7 +589,9 @@ func (c *TaskConfig) adjust() error {
 			}
 			globalConfigReferCount[configRefPrefixes[loaderIdx]+inst.LoaderConfigName]++
 			inst.Loader = new(LoaderConfig)
-			*inst.Loader = *rule // ref loader config
+			if rule != nil {
+				*inst.Loader = *rule // ref loader config
+			}
 		}
 		if inst.Loader == nil {
 			if len(c.Loaders) != 0 {
@@ -607,7 +611,9 @@ func (c *TaskConfig) adjust() error {
 			}
 			globalConfigReferCount[configRefPrefixes[syncerIdx]+inst.SyncerConfigName]++
 			inst.Syncer = new(SyncerConfig)
-			*inst.Syncer = *rule // ref syncer config
+			if rule != nil {
+				*inst.Syncer = *rule // ref syncer config
+			}
 		}
 		if inst.Syncer == nil {
 			if len(c.Syncers) != 0 {

dm/config/task_test.go

@@ -302,17 +302,62 @@ mysql-instances:
     loader-config-name: "global"
     syncer-config-name: "global"
 `
-	taskConfig := NewTaskConfig()
-	err := taskConfig.Decode(errorTaskConfig1)
+	errorTaskConfig3 := `---
+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"
+
+mydumpers:
+  global:
+`
+
+	dontPanicTaskConfig := `---
+name: test
+task-mode: all
+
+target-database:
+  host: "127.0.0.1"
+  port: 4000
+  user: "root"
+  password: ""
+
+mysql-instances:
+  - source-id: "mysql-replica-01"
+    syncer-config-name: "global1"
+    loader-config-name: "global2"
+
+loaders:
+  global2:
+
+syncers:
+  global1:
+`
+	err := NewTaskConfig().Decode(errorTaskConfig1)
 	// field server-id is not a member of TaskConfig
 	c.Check(err, NotNil)
 	c.Assert(err, ErrorMatches, "*line 18: field server-id not found in type config.MySQLInstance.*")
 
-	err = taskConfig.Decode(errorTaskConfig2)
+	err = NewTaskConfig().Decode(errorTaskConfig2)
 	// field name duplicate
 	c.Check(err, NotNil)
 	c.Assert(err, ErrorMatches, "*line 3: field name already set in type config.TaskConfig.*")
 
+	err = NewTaskConfig().Decode(errorTaskConfig3)
+	c.Check(err, NotNil)
+	c.Assert(err, ErrorMatches, "*Please check the `mydumper-path` config in task configuration file.*")
+
+	err = NewTaskConfig().Decode(dontPanicTaskConfig)
+	c.Check(err, IsNil)
+
 	filepath := path.Join(c.MkDir(), "test_invalid_task.yaml")
 	configContent := []byte(`---
 aaa: xxx
@@ -325,7 +370,7 @@ ignore-checking-items: ["all"]
 `)
 	err = os.WriteFile(filepath, configContent, 0o644)
 	c.Assert(err, IsNil)
-	taskConfig = NewTaskConfig()
+	taskConfig := NewTaskConfig()
 	err = taskConfig.DecodeFile(filepath)
 	c.Assert(err, NotNil)
 	c.Assert(err, ErrorMatches, "*line 2: field aaa not found in type config.TaskConfig.*")

tests/gtid/conf/dm-task.yaml

@@ -16,6 +16,14 @@ mysql-instances:
 
   - source-id: "mysql-replica-02"
     block-allow-list:  "instance"
+    syncer-config-name: "global1"
+    loader-config-name: "global2"
+
+loaders:
+  global2:
+
+syncers:
+  global1:
 
 black-white-list: # compatible with deprecated config
   instance: