MySQL Database Cannot Connect

Camunda 7 Topics Discussion & Questions
1

I am trying to setup Camunda with a MySQL database in Linux. I am using the the Tomcat 7.13 prepackaged distribution. MySQL database version is 8.021 and the J connector is the same version. I can connect to the database at the command prompt without any problems. Here is my server.xml connector info.

   <Resource name="jdbc/ProcessEngine"
          auth="Container"
          type="javax.sql.DataSource" 
          factory="org.apache.tomcat.jdbc.pool.DataSourceFactory"
          uniqueResourceName="process-engine"
		  testOnBorrow="true"
	      validationQuery="SELECT 1"
          driverClassName="com.mysql.jdbc.Driver" 
          url="jdbc:mysql://localhost:3306/camunda?autoReconnect=true"
          defaultTransactionIsolation="READ_COMMITTED"
          username="admin"  
          password="Localhost123!"
          maxActive="20"
          minIdle="1"
          maxIdle="100" />

Here is my log file that will fit in a post.

31-Jul-2020 08:32:46.640 SEVERE [main] org.apache.tomcat.jdbc.pool.ConnectionPool.init Unable to create initial connections of pool.
java.sql.SQLNonTransientConnectionException: Could not create connection to database server. Attempted reconnect 3 times. Giving up.
at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:110)
at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:97)
at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:89)
at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:63)
at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:73)
at com.mysql.cj.jdbc.ConnectionImpl.connectWithRetries(ConnectionImpl.java:906)
at com.mysql.cj.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:831)
at com.mysql.cj.jdbc.ConnectionImpl.(ConnectionImpl.java:456)
at com.mysql.cj.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:246)
at com.mysql.cj.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:197)
at org.apache.tomcat.jdbc.pool.PooledConnection.connectUsingDriver(PooledConnection.java:319)
at org.apache.tomcat.jdbc.pool.PooledConnection.connect(PooledConnection.java:212)
at org.apache.tomcat.jdbc.pool.ConnectionPool.createConnection(ConnectionPool.java:744)
at org.apache.tomcat.jdbc.pool.ConnectionPool.borrowConnection(ConnectionPool.java:676)
at org.apache.tomcat.jdbc.pool.ConnectionPool.init(ConnectionPool.java:483)
at org.apache.tomcat.jdbc.pool.ConnectionPool.(ConnectionPool.java:154)
at org.apache.tomcat.jdbc.pool.DataSourceProxy.pCreatePool(DataSourceProxy.java:118)
at org.apache.tomcat.jdbc.pool.DataSourceProxy.createPool(DataSourceProxy.java:107)
at org.apache.tomcat.jdbc.pool.DataSourceFactory.createDataSource(DataSourceFactory.java:560)
at org.apache.tomcat.jdbc.pool.DataSourceFactory.getObjectInstance(DataSourceFactory.java:244)
at org.apache.naming.factory.FactoryBase.getObjectInstance(FactoryBase.java:96)
at javax.naming.spi.NamingManager.getObjectInstance(NamingManager.java:321)
at org.apache.naming.NamingContext.lookup(NamingContext.java:857)
at org.apache.naming.NamingContext.lookup(NamingContext.java:160)
at org.apache.naming.NamingContext.lookup(NamingContext.java:843)
at org.apache.naming.NamingContext.lookup(NamingContext.java:174)
at org.apache.catalina.core.NamingContextListener.addResource(NamingContextListener.java:1017)
at org.apache.catalina.core.NamingContextListener.createNamingContext(NamingContextListener.java:557)
at org.apache.catalina.core.NamingContextListener.lifecycleEvent(NamingContextListener.java:253)
at org.apache.catalina.util.LifecycleBase.fireLifecycleEvent(LifecycleBase.java:123)
at org.apache.catalina.core.StandardServer.startInternal(StandardServer.java:922)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183)
at org.apache.catalina.startup.Catalina.start(Catalina.java:633)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:343)
at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:474)

2

Hi @withnoe

Possibly a security precaution. You could try adding a new administrator account:

mysql> CREATE USER 'monty'@'localhost' IDENTIFIED BY 'some_pass';
mysql> GRANT ALL PRIVILEGES ON *.* TO 'monty'@'localhost'
    ->     WITH GRANT OPTION;
mysql> CREATE USER 'monty'@'%' IDENTIFIED BY 'some_pass';
mysql> GRANT ALL PRIVILEGES ON *.* TO 'monty'@'%'
    ->     WITH GRANT OPTION;
3

I added another account but still have the same connection issue.

4

The solution is that in Windows you do not need to specify time zone in the server.xml file in the jdbc url. In Linux you must in order for it to connect to MySQL.

url=“jdbc:mysql://localhost:3306/dbname?serverTimezone=UTC”

5