java.net.ConnectException：从本地机器连接mysql docker时操作超时（连接超时）

Question

我正在尝试使用 scala 代码连接到在本地机器上运行的 mysql 容器。由于某种原因，我得到了操作超时（dockerIp）或连接被拒绝错误（localhost/127.0.0.1）。

docker run --name=mysql-docker -p3306:3306 -e MYSQL_ROOT_PASSWORD='root' -d mysql:latest
docker exec -it mysql-docker bash
mysql -u root -p
update mysql.user set host = ‘127.0.0.1’ where user=’root’;

我可以使用mysql -h 127.0.0.1 -P 3306 -u root -p从终端连接到 docker

以下是我的 scala 代码。

  val url = "jdbc:mysql://172.17.0.2:3006/mysql"
  val driver = "com.mysql.jdbc.Driver"
  val username = "root"
  val password = "root"
  Class.forName("com.mysql.jdbc.Driver")
  val connection = DriverManager.getConnection(url, username, password)
  val statement = connection.createStatement
  val rs = statement.executeQuery("SELECT host, user FROM user")
  connection.close

不幸的是，这段代码抛出了

The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.
        at com.mysql.cj.jdbc.exceptions.SQLError.createCommunicationsException(SQLError.java:174)
        at com.mysql.cj.jdbc.exceptions.SQLExceptionsMapping.translateException(SQLExceptionsMapping.java:64)
        at com.mysql.cj.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:828)
        at com.mysql.cj.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:448)
        at com.mysql.cj.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:241)
        at com.mysql.cj.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:198)
        at java.sql.DriverManager.getConnection(DriverManager.java:664)
        at java.sql.DriverManager.getConnection(DriverManager.java:247)
        at largedataprocessor.LargeDataProcessor$.delayedEndpoint$largedataprocessor$LargeDataProcessor$1(LargeDataProcessor.scala:35)
        at largedataprocessor.LargeDataProcessor$delayedInit$body.apply(LargeDataProcessor.scala:9)
        at scala.Function0.apply$mcV$sp(Function0.scala:39)
        at scala.Function0.apply$mcV$sp$(Function0.scala:39)
        at scala.runtime.AbstractFunction0.apply$mcV$sp(AbstractFunction0.scala:17)
        at scala.App$$anonfun$main$1.apply(App.scala:76)
        at scala.App$$anonfun$main$1.apply(App.scala:76)
        at scala.collection.immutable.List.foreach(List.scala:431)
        at scala.collection.generic.TraversableForwarder$class.foreach(TraversableForwarder.scala:35)
        at scala.App$class.main(App.scala:76)
        at largedataprocessor.LargeDataProcessor$.main(LargeDataProcessor.scala:9)
        at largedataprocessor.LargeDataProcessor.main(LargeDataProcessor.scala)
Caused by: com.mysql.cj.exceptions.CJCommunicationsException: Communications link failure

The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.
        at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
        at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
        at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
        at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
        at com.mysql.cj.exceptions.ExceptionFactory.createException(ExceptionFactory.java:61)
        at com.mysql.cj.exceptions.ExceptionFactory.createException(ExceptionFactory.java:105)
        at com.mysql.cj.exceptions.ExceptionFactory.createException(ExceptionFactory.java:151)
        at com.mysql.cj.exceptions.ExceptionFactory.createCommunicationsException(ExceptionFactory.java:167)
        at com.mysql.cj.protocol.a.NativeSocketConnection.connect(NativeSocketConnection.java:89)
        at com.mysql.cj.NativeSession.connect(NativeSession.java:119)
        at com.mysql.cj.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:948)
        at com.mysql.cj.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:818)
        ... 17 more
Caused by: java.net.ConnectException: Operation timed out (Connection timed out)
        at java.net.PlainSocketImpl.socketConnect(Native Method)
        at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:350)
        at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:206)
        at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:188)
        at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:392)
        at java.net.Socket.connect(Socket.java:607)
        at com.mysql.cj.protocol.StandardSocketFactory.connect(StandardSocketFactory.java:156)
        at com.mysql.cj.protocol.a.NativeSocketConnection.connect(NativeSocketConnection.java:63)
        ... 20 more

如果我使用“jdbc:mysql://127.0.0.1:3006/mysql”，则会收到连接被拒绝错误。

请指出我的错误。

Answer 1

在网络方面，一些 dockerized 进程运行在与非 dockerized 不同的主机上。因此，连接到容器内的localhost 或127.0.0.1 将连接回同一个容器，其中没有任何东西在端口 3306 上进行监听 - 你正确地得到了 connection refused。

如果您尝试在端口 3306 上连接到主机的 IP，您也可以

• 如果你的 mysql 只监听 localhost:3306，则连接被拒绝
• 如果您的主机的防火墙阻止访问，则获取超时

确保在预期成功之前配置这两个项目。

另一种选择是在主机网络上运行您的容器。那么就不需要暴露端口了（反正就是暴露了），连接到localhost应该可以达到预期的效果。

您可能想更熟悉Docker networking。

编辑：到目前为止，我试图解释为什么你会看到你提到的结果。一切都按设计工作。所以现在让我们弄清楚你需要做什么来获得连接：

• 请注意 127.0.0.1 不起作用
• 在容器内配置mysql监听0.0.0.0:3306
• 使用 -p 3306:3306 运行容器
• 打开主机的防火墙以允许 :3306 上的流量
• 运行您的客户端应用程序并尝试连接到：3306