diff --git a/CHANGELOG.md b/CHANGELOG.md
index 6dd14e2c..0973aa8a 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,7 @@
+# 0.4.2 (unknown)
+### Features / Enhancement
+- **Disclaimer**. Added page for Disclaimer.
+
 # 0.4.1 (2019-12-13)
 ### Features / Enhancement
 - **Spiderfile Optimization**. Stages changed from dictionary to array. [#358](https://github.com/crawlab-team/crawlab/issues/358)
diff --git a/Dockerfile b/Dockerfile
index ddb4d47e..390ece66 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -56,4 +56,4 @@ EXPOSE 8080
 EXPOSE 8000
 
 # start backend
-CMD ["/bin/sh", "/app/docker_init.sh"]
+CMD ["/bin/sh", "./wait-for-it.sh", "mongo:27017", "--", "/bin/sh", "/app/docker_init.sh"]
diff --git a/backend/model/node.go b/backend/model/node.go
index a24b36e3..d662ab6d 100644
--- a/backend/model/node.go
+++ b/backend/model/node.go
@@ -143,6 +143,7 @@ func (n *Node) GetTasks() ([]Task, error) {
 	return tasks, nil
 }
 
+// 节点列表
 func GetNodeList(filter interface{}) ([]Node, error) {
 	s, c := database.GetCol("nodes")
 	defer s.Close()
@@ -156,6 +157,7 @@ func GetNodeList(filter interface{}) ([]Node, error) {
 	return results, nil
 }
 
+// 节点信息
 func GetNode(id bson.ObjectId) (Node, error) {
 	var node Node
 
@@ -176,6 +178,7 @@ func GetNode(id bson.ObjectId) (Node, error) {
 	return node, nil
 }
 
+// 节点信息
 func GetNodeByKey(key string) (Node, error) {
 	s, c := database.GetCol("nodes")
 	defer s.Close()
@@ -191,6 +194,7 @@ func GetNodeByKey(key string) (Node, error) {
 	return node, nil
 }
 
+// 更新节点
 func UpdateNode(id bson.ObjectId, item Node) error {
 	s, c := database.GetCol("nodes")
 	defer s.Close()
@@ -206,6 +210,7 @@ func UpdateNode(id bson.ObjectId, item Node) error {
 	return nil
 }
 
+// 任务列表
 func GetNodeTaskList(id bson.ObjectId) ([]Task, error) {
 	node, err := GetNode(id)
 	if err != nil {
@@ -218,6 +223,7 @@ func GetNodeTaskList(id bson.ObjectId) ([]Task, error) {
 	return tasks, nil
 }
 
+// 节点数
 func GetNodeCount(query interface{}) (int, error) {
 	s, c := database.GetCol("nodes")
 	defer s.Close()
diff --git a/backend/services/log.go b/backend/services/log.go
index 60909c61..2034794d 100644
--- a/backend/services/log.go
+++ b/backend/services/log.go
@@ -49,10 +49,8 @@ func GetRemoteLog(task model.Task) (logStr string, err error) {
 	select {
 	case logStr = <-ch:
 		log.Infof("get remote log")
-		break
 	case <-time.After(30 * time.Second):
 		logStr = "get remote log timeout"
-		break
 	}
 
 	return logStr, nil
diff --git a/backend/services/node.go b/backend/services/node.go
index 36934746..e6c2ac08 100644
--- a/backend/services/node.go
+++ b/backend/services/node.go
@@ -50,36 +50,44 @@ func GetNodeData() (Data, error) {
 	return data, err
 }
 
+func GetRedisNode(key string) (*Data, error) {
+	// 获取节点数据
+	value, err := database.RedisClient.HGet("nodes", key)
+	if err != nil {
+		log.Errorf(err.Error())
+		return nil, err
+	}
+
+	// 解析节点列表数据
+	var data Data
+	if err := json.Unmarshal([]byte(value), &data); err != nil {
+		log.Errorf(err.Error())
+		return nil, err
+	}
+	return &data, nil
+}
+
 // 更新所有节点状态
 func UpdateNodeStatus() {
 	// 从Redis获取节点keys
 	list, err := database.RedisClient.HKeys("nodes")
 	if err != nil {
-		log.Errorf(err.Error())
+		log.Errorf("get redis node keys error: %s", err.Error())
 		return
 	}
 
 	// 遍历节点keys
 	for _, key := range list {
-		// 获取节点数据
-		value, err := database.RedisClient.HGet("nodes", key)
+
+		data, err := GetRedisNode(key)
 		if err != nil {
-			log.Errorf(err.Error())
-			return
+			continue
 		}
-
-		// 解析节点列表数据
-		var data Data
-		if err := json.Unmarshal([]byte(value), &data); err != nil {
-			log.Errorf(err.Error())
-			return
-		}
-
 		// 如果记录的更新时间超过60秒，该节点被认为离线
 		if time.Now().Unix()-data.UpdateTsUnix > 60 {
 			// 在Redis中删除该节点
 			if err := database.RedisClient.HDel("nodes", data.Key); err != nil {
-				log.Errorf(err.Error())
+				log.Errorf("delete redis node key error:%s, key:%s", err.Error(), data.Key)
 			}
 			continue
 		}
@@ -94,7 +102,8 @@ func UpdateNodeStatus() {
 	model.ResetNodeStatusToOffline(list)
 }
 
-func handleNodeInfo(key string, data Data) {
+// 处理接到信息
+func handleNodeInfo(key string, data *Data) {
 	// 添加同步锁
 	v, err := database.RedisClient.Lock(key)
 	if err != nil {
diff --git a/docker-compose.yml b/docker-compose.yml
index 270c986c..3ed6c76a 100644
--- a/docker-compose.yml
+++ b/docker-compose.yml
@@ -4,13 +4,13 @@ services:
     image: tikazyq/crawlab:latest
     container_name: master
     environment:
-      CRAWLAB_API_ADDRESS: "http://localhost:8000"
-      CRAWLAB_SERVER_MASTER: "Y"
-      CRAWLAB_MONGO_HOST: "mongo"
-      CRAWLAB_REDIS_ADDRESS: "redis"
+      CRAWLAB_API_ADDRESS: "http://localhost:8000"  # backend API address 后端 API 地址，设置为 http://<宿主机IP>:<端口>，端口为映射出来的端口
+      CRAWLAB_SERVER_MASTER: "Y"  # whether to be master node 是否为主节点，主节点为 Y，工作节点为 N
+      CRAWLAB_MONGO_HOST: "mongo"  # MongoDB host address MongoDB 的地址，在 docker compose 网络中，直接引用服务名称
+      CRAWLAB_REDIS_ADDRESS: "redis"  # Redis host address Redis 的地址，在 docker compose 网络中，直接引用服务名称
     ports:    
-      - "8080:8080" # frontend
-      - "8000:8000" # backend
+      - "8080:8080" # frontend port mapping 前端端口映射
+      - "8000:8000" # backend port mapping 后端端口映射 
     depends_on:
       - mongo
       - redis
@@ -27,14 +27,14 @@ services:
   mongo:
     image: mongo:latest
     restart: always
-    volumes:
-      - "/opt/crawlab/mongo/data/db:/data/db"
-    ports:
-      - "27017:27017"
+    # volumes:
+    #   - "/opt/crawlab/mongo/data/db:/data/db"  # make data persistent 持久化
+    # ports:
+    #   - "27017:27017"  # expose port to host machine 暴露接口到宿主机
   redis:
     image: redis:latest
     restart: always
-    volumes:
-      - "/opt/crawlab/redis/data:/data"
-    ports:
-      - "6379:6379"
\ No newline at end of file
+    # volumes:
+    #   - "/opt/crawlab/redis/data:/data"  # make data persistent 持久化
+    # ports:
+    #   - "6379:6379"  # expose port to host machine 暴露接口到宿主机
\ No newline at end of file
diff --git a/wait-for-it.sh b/wait-for-it.sh
new file mode 100755
index 00000000..607a7d67
--- /dev/null
+++ b/wait-for-it.sh
@@ -0,0 +1,178 @@
+#!/usr/bin/env bash
+#   Use this script to test if a given TCP host/port are available
+
+WAITFORIT_cmdname=${0##*/}
+
+echoerr() { if [[ $WAITFORIT_QUIET -ne 1 ]]; then echo "$@" 1>&2; fi }
+
+usage()
+{
+    cat << USAGE >&2
+Usage:
+    $WAITFORIT_cmdname host:port [-s] [-t timeout] [-- command args]
+    -h HOST | --host=HOST       Host or IP under test
+    -p PORT | --port=PORT       TCP port under test
+                                Alternatively, you specify the host and port as host:port
+    -s | --strict               Only execute subcommand if the test succeeds
+    -q | --quiet                Don't output any status messages
+    -t TIMEOUT | --timeout=TIMEOUT
+                                Timeout in seconds, zero for no timeout
+    -- COMMAND ARGS             Execute command with args after the test finishes
+USAGE
+    exit 1
+}
+
+wait_for()
+{
+    if [[ $WAITFORIT_TIMEOUT -gt 0 ]]; then
+        echoerr "$WAITFORIT_cmdname: waiting $WAITFORIT_TIMEOUT seconds for $WAITFORIT_HOST:$WAITFORIT_PORT"
+    else
+        echoerr "$WAITFORIT_cmdname: waiting for $WAITFORIT_HOST:$WAITFORIT_PORT without a timeout"
+    fi
+    WAITFORIT_start_ts=$(date +%s)
+    while :
+    do
+        if [[ $WAITFORIT_ISBUSY -eq 1 ]]; then
+            nc -z $WAITFORIT_HOST $WAITFORIT_PORT
+            WAITFORIT_result=$?
+        else
+            (echo > /dev/tcp/$WAITFORIT_HOST/$WAITFORIT_PORT) >/dev/null 2>&1
+            WAITFORIT_result=$?
+        fi
+        if [[ $WAITFORIT_result -eq 0 ]]; then
+            WAITFORIT_end_ts=$(date +%s)
+            echoerr "$WAITFORIT_cmdname: $WAITFORIT_HOST:$WAITFORIT_PORT is available after $((WAITFORIT_end_ts - WAITFORIT_start_ts)) seconds"
+            break
+        fi
+        sleep 1
+    done
+    return $WAITFORIT_result
+}
+
+wait_for_wrapper()
+{
+    # In order to support SIGINT during timeout: http://unix.stackexchange.com/a/57692
+    if [[ $WAITFORIT_QUIET -eq 1 ]]; then
+        timeout $WAITFORIT_BUSYTIMEFLAG $WAITFORIT_TIMEOUT $0 --quiet --child --host=$WAITFORIT_HOST --port=$WAITFORIT_PORT --timeout=$WAITFORIT_TIMEOUT &
+    else
+        timeout $WAITFORIT_BUSYTIMEFLAG $WAITFORIT_TIMEOUT $0 --child --host=$WAITFORIT_HOST --port=$WAITFORIT_PORT --timeout=$WAITFORIT_TIMEOUT &
+    fi
+    WAITFORIT_PID=$!
+    trap "kill -INT -$WAITFORIT_PID" INT
+    wait $WAITFORIT_PID
+    WAITFORIT_RESULT=$?
+    if [[ $WAITFORIT_RESULT -ne 0 ]]; then
+        echoerr "$WAITFORIT_cmdname: timeout occurred after waiting $WAITFORIT_TIMEOUT seconds for $WAITFORIT_HOST:$WAITFORIT_PORT"
+    fi
+    return $WAITFORIT_RESULT
+}
+
+# process arguments
+while [[ $# -gt 0 ]]
+do
+    case "$1" in
+        *:* )
+        WAITFORIT_hostport=(${1//:/ })
+        WAITFORIT_HOST=${WAITFORIT_hostport[0]}
+        WAITFORIT_PORT=${WAITFORIT_hostport[1]}
+        shift 1
+        ;;
+        --child)
+        WAITFORIT_CHILD=1
+        shift 1
+        ;;
+        -q | --quiet)
+        WAITFORIT_QUIET=1
+        shift 1
+        ;;
+        -s | --strict)
+        WAITFORIT_STRICT=1
+        shift 1
+        ;;
+        -h)
+        WAITFORIT_HOST="$2"
+        if [[ $WAITFORIT_HOST == "" ]]; then break; fi
+        shift 2
+        ;;
+        --host=*)
+        WAITFORIT_HOST="${1#*=}"
+        shift 1
+        ;;
+        -p)
+        WAITFORIT_PORT="$2"
+        if [[ $WAITFORIT_PORT == "" ]]; then break; fi
+        shift 2
+        ;;
+        --port=*)
+        WAITFORIT_PORT="${1#*=}"
+        shift 1
+        ;;
+        -t)
+        WAITFORIT_TIMEOUT="$2"
+        if [[ $WAITFORIT_TIMEOUT == "" ]]; then break; fi
+        shift 2
+        ;;
+        --timeout=*)
+        WAITFORIT_TIMEOUT="${1#*=}"
+        shift 1
+        ;;
+        --)
+        shift
+        WAITFORIT_CLI=("$@")
+        break
+        ;;
+        --help)
+        usage
+        ;;
+        *)
+        echoerr "Unknown argument: $1"
+        usage
+        ;;
+    esac
+done
+
+if [[ "$WAITFORIT_HOST" == "" || "$WAITFORIT_PORT" == "" ]]; then
+    echoerr "Error: you need to provide a host and port to test."
+    usage
+fi
+
+WAITFORIT_TIMEOUT=${WAITFORIT_TIMEOUT:-15}
+WAITFORIT_STRICT=${WAITFORIT_STRICT:-0}
+WAITFORIT_CHILD=${WAITFORIT_CHILD:-0}
+WAITFORIT_QUIET=${WAITFORIT_QUIET:-0}
+
+# check to see if timeout is from busybox?
+WAITFORIT_TIMEOUT_PATH=$(type -p timeout)
+WAITFORIT_TIMEOUT_PATH=$(realpath $WAITFORIT_TIMEOUT_PATH 2>/dev/null || readlink -f $WAITFORIT_TIMEOUT_PATH)
+if [[ $WAITFORIT_TIMEOUT_PATH =~ "busybox" ]]; then
+        WAITFORIT_ISBUSY=1
+        WAITFORIT_BUSYTIMEFLAG="-t"
+
+else
+        WAITFORIT_ISBUSY=0
+        WAITFORIT_BUSYTIMEFLAG=""
+fi
+
+if [[ $WAITFORIT_CHILD -gt 0 ]]; then
+    wait_for
+    WAITFORIT_RESULT=$?
+    exit $WAITFORIT_RESULT
+else
+    if [[ $WAITFORIT_TIMEOUT -gt 0 ]]; then
+        wait_for_wrapper
+        WAITFORIT_RESULT=$?
+    else
+        wait_for
+        WAITFORIT_RESULT=$?
+    fi
+fi
+
+if [[ $WAITFORIT_CLI != "" ]]; then
+    if [[ $WAITFORIT_RESULT -ne 0 && $WAITFORIT_STRICT -eq 1 ]]; then
+        echoerr "$WAITFORIT_cmdname: strict mode, refusing to execute subprocess"
+        exit $WAITFORIT_RESULT
+    fi
+    exec "${WAITFORIT_CLI[@]}"
+else
+    exit $WAITFORIT_RESULT
+fi
\ No newline at end of file