I am creating a PySpark 3.4.1 application for development in docker with Python 3.11.5, It should be able to connect to multiple types of databases throught JDBC conections. I am testing the connection with a local Oracle DB that I set up using docker in another container. However, I am getting the following error:

我正在创建一个PySpark 3.4.1应用程序在与Python3.11.5对接开发，它应该能够连接到多种类型的数据库通过JDBC连接。我正在测试与本地Oracle数据库的连接，该数据库是我在另一个容器中使用docker设置的。但是，我收到以下错误：

Py4JJavaError: An error occurred while calling o316.load.
: java.sql.SQLException: ORA-12541: Cannot connect. No listener at host 127.0.0.1 port 1521. (CONNECTION_ID=ZHRvV1iVRICqrdGeoIq7BQ==)

When I run (using jar: "ojdbc11.jar"):

当我运行时(使用JAR：“ojdbc11.jar”)：

connection_opts = {
    "driver": "oracle.jdbc.driver.OracleDriver",
    "url": "jdbc:oracle:thin:@127.0.0.1:1521/FREEPDB1",
    "dbtable": "select * from xtable",
    "user": "my_db_admin",
    "password": "20pwd23",
}
df = spark.read.format("jdbc").options(**connection_opts).load()

The docker-compose.yml file is as follows:

Docker-compose.yml文件如下所示：

version: "3.3"
services:
  spark-master:
    image: my_pyspark_image:latest
    tty: true
    stdin_open: true
    ports:
      - "9090:8080"
      - "7077:7077"
  oracle-localdb:
    # Creation reference: https://hub.docker.com/r/gvenzl/oracle-free
    image: gvenzl/oracle-free:slim
    shm_size: 1g
    ports:
      - '1521:1521'
    environment:
      ORACLE_RANDOM_PASSWORD: true
      APP_USER: my_db_admin
      APP_USER_PASSWORD: 20pwd23
    volumes:
      - type: volume
        source: pyspark_oracle-volume
        target: /opt/oracle/oradata
volumes:
  pyspark_oracle-volume:
    # external: true

When I run lsnrctl status:

当我运行lsnrctl状态时：

LSNRCTL for Linux: Version 23.0.0.0.0 - Developer-Release on 09-SEP-2023 18:49:38

Copyright (c) 1991, 2023, Oracle.  All rights reserved.

Connecting to (DESCRIPTION=(ADDRESS=(PROTOCOL=IPC)(KEY=EXTPROC_FOR_FREE)))
STATUS of the LISTENER
------------------------
Alias                     LISTENER
Version                   TNSLSNR for Linux: Version 23.0.0.0.0 - Developer-Release
Start Date                09-SEP-2023 18:47:38
Uptime                    0 days 0 hr. 1 min. 59 sec
Trace Level               off
Security                  ON: Local OS Authentication
SNMP                      OFF
Default Service           FREE
Listener Parameter File   /opt/oracle/product/23c/dbhomeFree/network/admin/listener.ora
Listener Log File         /opt/oracle/diag/tnslsnr/6b3c2441425c/listener/alert/log.xml
Listening Endpoints Summary...
  (DESCRIPTION=(ADDRESS=(PROTOCOL=ipc)(KEY=EXTPROC_FOR_FREE)))
  (DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=0.0.0.0)(PORT=1521)))
Services Summary...
Service "FREE" has 1 instance(s).
  Instance "FREE", status READY, has 1 handler(s) for this service...
Service "FREEXDB" has 1 instance(s).
  Instance "FREE", status READY, has 0 handler(s) for this service...
Service "fb99f7d127aa0bafe0536402000a43b5" has 1 instance(s).
  Instance "FREE", status READY, has 1 handler(s) for this service...
Service "freepdb1" has 1 instance(s).
  Instance "FREE", status READY, has 1 handler(s) for this service...
The command completed successfully

The listener.ora:

The listener.ora：

LISTENER =
  (DESCRIPTION_LIST =
    (DESCRIPTION =
      (ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC_FOR_FREE))
      (ADDRESS = (PROTOCOL = TCP)(HOST = 0.0.0.0)(PORT = 1521))
    )
  )

DEFAULT_SERVICE_LISTENER = FREE

The tnsnames.ora:

Tnsnames.ora：

FREE =
  (DESCRIPTION =
    (ADDRESS = (PROTOCOL = TCP)(HOST = 0.0.0.0)(PORT = 1521))
    (CONNECT_DATA =
      (SERVER = DEDICATED)
      (SERVICE_NAME = FREE)
    )
  )

FREEPDB1 =
  (DESCRIPTION =
    (ADDRESS = (PROTOCOL = TCP)(HOST = 0.0.0.0)(PORT = 1521))
    (CONNECT_DATA =
      (SERVER = DEDICATED)
      (SERVICE_NAME = FREEPDB1)
    )
  )

EXTPROC_CONNECTION_DATA =
  (DESCRIPTION =
    (ADDRESS_LIST =
      (ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC_FOR_FREE))
    )
    (CONNECT_DATA =
      (SID = PLSExtProc)
      (PRESENTATION = RO)
    )
  )

I already tried the same connection with other custom created databases and with sys users. Also, I tried creating the container with multiple ports but no luck. Finally, I do not know if this will help but, I tried this and no luck either.

我已经对其他定制创建的数据库和sys用户尝试了相同的连接。此外，我尝试创建具有多个端口的容器，但没有成功。最后，我不知道这是否会有帮助，但是，我尝试了这个，也没有成功。

I tried making the connection with the oracledb python library:

我尝试与oracledb python库建立连接：

import oracledb

connection = oracledb.connect(user="my_db_admin", password='20pwd23',
                             host="127.0.0.1", port=1521, service_name="freepdb1")

But I get this:

但我明白：

OperationalError: DPY-6005: cannot connect to database (CONNECTION_ID=M88go017TW5iuuV35FqWhw==).
[Errno 111] Connection refused

Could somebody explain me what I'm missing, how to solve it and if possible how to better understand the .ora files

谁能给我解释一下我遗漏了什么，如何解决它，如果可能的话，如何更好地理解.ora文件

I want to start with a question:

我想从一个问题开始：

Are you running oracle database in your 'spark-master' container?

你在你的“星火大师”容器中运行甲骨文数据库吗？

Because, that is how you have configured your database connection by specifying localhost/127.0.0.1

因为，这就是通过指定localhost/127.0.0.1来配置数据库连接的方式

localhost is local to the container. There is no database running in your 'spark-master' container. It is running as a service/container alongside your 'spark-master' container. When utilizing docker compose, service discovery is happening behind the scenes and you can access them by name.
To contact the oracle database service, you provide the name oracle-localdb

localhost对于容器是本地的。您的'spark-master'容器中没有运行数据库。它作为一个服务/容器与你的“spark-master”容器一起运行。当使用Docker compose时，服务发现是在后台进行的，您可以通过名称访问它们。要联系Oracle数据库服务，请提供名称oracle-localdb

Now, this should work for you:

现在，这对你来说应该是有效的：

import oracledb

connection = oracledb.connect(user="my_db_admin", password='20pwd23',
                             host="oracle-localdb", port=1521, service_name="freepdb1")  

Best of luck!

祝你好运！