Hive-Server unable to read volumes from DataNode / Volumes don´t work

Question

I have got the following setup for a local Hive-Server with Hadoop:

version: "3"

services:
  namenode:
    image: bde2020/hadoop-namenode:2.0.0-hadoop3.2.1-java8
    container_name: namenode
    restart: always
    ports:
      - 9870:9870
      - 9000:9000
    volumes:
      - ./hdfs/namenode:/hadoop/dfs/name
    environment:
      - CLUSTER_NAME=test
    env_file:
      - ./hadoop.env

  datanode:
    image: bde2020/hadoop-datanode:2.0.0-hadoop3.2.1-java8
    container_name: datanode
    restart: always
    volumes:
      - ./hdfs/datanode:/hadoop/dfs/data
    environment:
      SERVICE_PRECONDITION: "namenode:9870"
    env_file:
      - ./hadoop.env


  hive-server:
    image: bde2020/hive:2.3.2-postgresql-metastore
    container_name: hive-server
    volumes:
      - ./employee:/employee
    env_file:
      - ./hadoop-hive.env
    environment:
      HIVE_CORE_CONF_javax_jdo_option_ConnectionURL: "jdbc:postgresql://hive-metastore/metastore"
      SERVICE_PRECONDITION: "hive-metastore:9083"
    ports:
      - "10000:10000"

  hive-metastore:
    image: bde2020/hive:2.3.2-postgresql-metastore
    env_file:
      - ./hadoop-hive.env
    command: /opt/hive/bin/hive --service metastore
    environment:
      SERVICE_PRECONDITION: "namenode:9000 namenode:9870 hive-metastore-postgresql:5432"
    ports:
      - "9083:9083"

  hive-metastore-postgresql:
    image: bde2020/hive-metastore-postgresql:2.3.0

  presto-coordinator:
    image: shawnzhu/prestodb:0.181
    ports:
      - "8080:8080"

I start everthing with docker-compose and it works fine. I enter the hive-server container.

docker exec -it hive-server /bin/bash

I run hive -f employee_table.sql to create a schema in Hive.

Then I store a little .csv in Hadoop:

hadoop fs -put employee.csv hdfs://namenode:9000/user/hive/warehouse/testdb.db/employee

This also works and after I run docker-compose down I restart the services and all data I inserted before is gone. I don´t really understand this, I can even see the files in the following subdirectory:

hdfs\datanode\current\BP-267128047-172.27.0.7-1633966854402\current\finalized\subdir0\subdir0

What am I doing wrong here? Is something wrong with my volumes? Ports?