Oozie时出现Caused by: com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure？

　　不多说，直接上干货！

　　问题详情

[hadoop@bigdatamaster oozie-4.1.-cdh5.5.4]$ bin/ooziedb.sh create -sqlfile oozie.sql -run DB Connection

[hadoop@bigdatamaster oozie-4.1.-cdh5.5.4]$ bin/ooziedb.sh create -sqlfile oozie.sql -run DB Connection
  setting CATALINA_OPTS="$CATALINA_OPTS -Xmx1024m"

Validate DB Connection

Error: Could not connect to the database: com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure

The last packet sent successfully to the server was  milliseconds ago. The driver has not received any packets from the server.

Stack trace for the error was (for debug purposes):
--------------------------------------
java.lang.Exception: Could not connect to the database: com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure

The last packet sent successfully to the server was  milliseconds ago. The driver has not received any packets from the server.
    at org.apache.oozie.tools.OozieDBCLI.validateConnection(OozieDBCLI.java:)
    at org.apache.oozie.tools.OozieDBCLI.createDB(OozieDBCLI.java:)
    at org.apache.oozie.tools.OozieDBCLI.run(OozieDBCLI.java:)
    at org.apache.oozie.tools.OozieDBCLI.main(OozieDBCLI.java:)
Caused by: com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure

The last packet sent successfully to the server was  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:)
    at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:)
    at java.lang.reflect.Constructor.newInstance(Constructor.java:)
    at com.mysql.jdbc.Util.handleNewInstance(Util.java:)
    at com.mysql.jdbc.SQLError.createCommunicationsException(SQLError.java:)
    at com.mysql.jdbc.MysqlIO.<init>(MysqlIO.java:)
    at com.mysql.jdbc.ConnectionImpl.coreConnect(ConnectionImpl.java:)
    at com.mysql.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:)
    at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:)
    at com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:)
    at com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:)
    at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:)
    at java.lang.reflect.Constructor.newInstance(Constructor.java:)
    at com.mysql.jdbc.Util.handleNewInstance(Util.java:)
    at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:)
    at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:)
    at java.sql.DriverManager.getConnection(DriverManager.java:)
    at java.sql.DriverManager.getConnection(DriverManager.java:)
    at org.apache.oozie.tools.OozieDBCLI.createConnection(OozieDBCLI.java:)
    at org.apache.oozie.tools.OozieDBCLI.validateConnection(OozieDBCLI.java:)
    ...  more
Caused by: java.net.ConnectException: Connection refused
    at java.net.PlainSocketImpl.socketConnect(Native Method)
    at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:)
    at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:)
    at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:)
    at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:)
    at java.net.Socket.connect(Socket.java:)
    at java.net.Socket.connect(Socket.java:)
    at java.net.Socket.<init>(Socket.java:)
    at java.net.Socket.<init>(Socket.java:)
    at com.mysql.jdbc.StandardSocketFactory.connect(StandardSocketFactory.java:)
    at com.mysql.jdbc.MysqlIO.<init>(MysqlIO.java:)
    ...  more
--------------------------------------

解决办法

　　分析1： 是否你是mysql服务进程么开启。

　　　　比如我的mysql是在root用户下安装的，且安装目录是在/home/hadoop下。当然大家可以将mysql服务进程设置为开机启动。

　　分析2：还有，是不是你的oozie用户下的主机，没有在数据库列表里。

    <property>
        <name>oozie.db.schema.name</name>
        <value>oozie</value>
        <description>
            Oozie DataBase Name
        </description>
    </property>
    <property>
        <name>oozie.service.JPAService.create.db.schema</name>
        <value>false</value>
        <description>
            Creates Oozie DB.
            If set to true, it creates the DB schema if it does not exist. If the DB schema exists is a NOP.
            If set to false, it does not create the DB schema. If the DB schema does not exist it fails start up.
        </description>
    </property>
    <property>
        <name>oozie.service.JPAService.jdbc.driver</name>
        <value>com.mysql.jdbc.Driver</value>
        <description>
            JDBC driver class.
        </description>
    </property>
    <property>
        <name>oozie.service.JPAService.jdbc.url</name>
        <value>jdbc:mysql://bigdatamaster:3306/oozie?createDatabaseIfNotExist=true</value>
        <description>
            JDBC URL.
        </description>
    </property>
    <property>
        <name>oozie.service.JPAService.jdbc.username</name>
        <value>oozie</value>
        <description>
            DB user name.
        </description>
    </property>
    <property>
        <name>oozie.service.JPAService.jdbc.password</name>
        <value>oozie</value>
        <description>
            DB user password.
            IMPORTANT: if password is emtpy leave a  space string, the service trims the value,
                       if empty Configuration assumes it is NULL.
        </description>
    </property>

　　因为，也许你会像我这样，之前在$OOZIE_HOME/conf/下的oozie-site.xml里，已经配置好了。

　　但是呢，忘记设置了。

[root@bigdatamaster hadoop]# mysql -uroot -p
Enter password: （默认回车）
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is
Server version: 5.1. Source distribution

Copyright (c) , , Oracle and/or its affiliates. All rights reserved.

Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

mysql> select user,host,password from mysql.user;
+------+---------------+-------------------------------------------+
| user | host          | password                                  |
+------+---------------+-------------------------------------------+
| root | localhost     |                                           |
| root | bigdatamaster |                                           |
| root | 127.0.0.1     |                                           |
|      | localhost     |                                           |
|      | bigdatamaster |                                           |
| hive | %             | *4DF1D66463C18D44E3B001A8FB1BBFBEA13E27FC |
| hive | bigdatamaster | *4DF1D66463C18D44E3B001A8FB1BBFBEA13E27FC |
| hive | localhost     | *4DF1D66463C18D44E3B001A8FB1BBFBEA13E27FC |
+------+---------------+-------------------------------------------+
 rows in set (0.00 sec)

mysql> 

　　那么，现在，我们开启它。

mysql> create user 'oozie'@'%' identified by 'oozie';
Query OK,  rows affected (0.00 sec)

mysql> GRANT ALL PRIVILEGES ON *.* to 'oozie'@'%' IDENTIFIED BY 'oozie' WITH GRANT OPTION;
Query OK,  rows affected (0.00 sec)

mysql> GRANT ALL PRIVILEGES ON *.* to 'oozie'@'bigdatamaster' IDENTIFIED BY 'oozie' WITH GRANT OPTION;
Query OK,  rows affected (0.00 sec)

mysql> GRANT ALL PRIVILEGES ON *.* to 'oozie'@'localhost' IDENTIFIED BY 'oozie' WITH GRANT OPTION;
Query OK,  rows affected (0.00 sec)

mysql> flush privileges;
Query OK,  rows affected (0.00 sec)

mysql> select user,host,password from mysql.user;
+-------+---------------+-------------------------------------------+
| user  | host          | password                                  |
+-------+---------------+-------------------------------------------+
| root  | localhost     |                                           |
| root  | bigdatamaster |                                           |
| root  | 127.0.0.1     |                                           |
|       | localhost     |                                           |
|       | bigdatamaster |                                           |
| hive  | %             | *4DF1D66463C18D44E3B001A8FB1BBFBEA13E27FC |
| hive  | bigdatamaster | *4DF1D66463C18D44E3B001A8FB1BBFBEA13E27FC |
| hive  | localhost     | *4DF1D66463C18D44E3B001A8FB1BBFBEA13E27FC |
| oozie | %             | *2B03FE0359FAD3B80620490CE614F8622E0828CD |
| oozie | bigdatamaster | *2B03FE0359FAD3B80620490CE614F8622E0828CD |
| oozie | localhost     | *2B03FE0359FAD3B80620490CE614F8622E0828CD |
+-------+---------------+-------------------------------------------+
 rows in set (0.00 sec)

mysql> exit;
Bye
[root@bigdatamaster hadoop]#

[hadoop@bigdatamaster oozie-4.1.-cdh5.5.4]$ bin/ooziedb.sh create -sqlfile oozie.sql -run DB Connection
  setting CATALINA_OPTS="$CATALINA_OPTS -Xmx1024m"

Validate DB Connection
DONE
Check DB schema does not exist
DONE
Check OOZIE_SYS table does not exist
DONE
Create SQL schema
DONE
Create OOZIE_SYS table
DONE

Oozie DB has been created for Oozie version '4.1.0-cdh5.5.4'

The SQL commands have been written to: oozie.sql

　　

　　

[hadoop@bigdatamaster oozie-4.1.-cdh5.5.4]$ pwd
/home/hadoop/app/oozie-4.1.-cdh5.5.4
[hadoop@bigdatamaster oozie-4.1.-cdh5.5.4]$ ls
bin   docs  libext    LICENSE.txt  NOTICE.txt            oozie-core             oozie-hadooplibs-4.1.-cdh5.5.4.tar.gz  oozie-sharelib-4.1.-cdh5.5.4.tar.gz       oozie.sql  release-log.txt
conf  lib   libtools  logs         oozie-4.1.-cdh5.5.4  oozie-examples.tar.gz  oozie-server                            oozie-sharelib-4.1.-cdh5.5.4-yarn.tar.gz  oozie.war  src
[hadoop@bigdatamaster oozie-4.1.-cdh5.5.4]$ 

　　成功！

然后呢，大家也许还会出现如下问题：

Oozie安装时放置Mysql驱动包的总结（网上最全）

Oozie时出现org.apache.oozie.service.ServiceException: E0103: Could not load service classes, Cannot load JDBC driver class 'com.mysql.jdbc.Driver'

Oozie时bin/oozied.sh start或bin/oozied.sh run出现Bootstrap进程无法启动，http://bigdatamaster:11000/oozie界面也无法打开？E0103: Could not load service classes,

java.lang.ClassNotFoundException: Class org.apache.oozie.ser

Oozie时bin/oozied.sh start或bin/oozied.sh run出现Bootstrap进程无法启动，http://bigdatamaster:11000/oozie界面也无法打开？

Oozie时出现Caused by: com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure？

Oozie时出现Exception in thread "main" java.lang.UnsupportedClassVersionError: com/mysql/jdbc/Driver : Unsupported major.minor version 52.0？

CDH版本的oozie安装执行bin/oozie-setup.sh prepare-war，没生成oozie.war?