ranger: "C3P0PooledConnectionPoolManager" WARN messages in Ranger Admin logs

[kpgtek]

We found the following WARN messages in Ranger Admin logs for every minutes, when tdp-observability collection is deployed :

WARN  [C3P0PooledConnectionPoolManager[identityToken->xxxxxxxxxxxxxx|xxxxxxx]-HelperThread-#1:Slf4jMLog$Slf4jMLogger$WarnLogger@220] - Having failed to acquire a resource, com.mchange.v2.resourcepool.BasicResourcePool@xxxxxx is interrupting all Threads waiting on a resource to check out. Will try again in response to new client requests.
WARN  [C3P0PooledConnectionPoolManager[identityToken->xxxxxxxxxxxxxx|xxxxxxx]-HelperThread-#1:Slf4jMLog$Slf4jMLogger$WarnLogger@223] - com.mchange.v2.resourcepool.BasicResourcePool$ScatteredAcquireTask@xxxxxx -- Acquisition Attempt Failed!!! Clearing pending acquires. While trying to acquire a needed new resource, we failed to succeed more than the maximum number of allowed acquisition attempts (30). Last acquisition attempt exception: 
java.sql.SQLException: No suitable driver
at java.sql.DriverManager.getDriver(DriverManager.java:315)
	at com.mchange.v2.c3p0.DriverManagerDataSource.driver(DriverManagerDataSource.java:285)
	at com.mchange.v2.c3p0.DriverManagerDataSource.getConnection(DriverManagerDataSource.java:175)
	at com.mchange.v2.c3p0.WrapperConnectionPoolDataSource.getPooledConnection(WrapperConnectionPoolDataSource.java:220)
	at com.mchange.v2.c3p0.WrapperConnectionPoolDataSource.getPooledConnection(WrapperConnectionPoolDataSource.java:206)
	at com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool$1PooledConnectionResourcePoolManager.acquireResource(C3P0PooledConnectionPool.java:203)
	at com.mchange.v2.resourcepool.BasicResourcePool.doAcquire(BasicResourcePool.java:1138)
	at com.mchange.v2.resourcepool.BasicResourcePool.doAcquireAndDecrementPendingAcquiresWithinLockOnSuccess(BasicResourcePool.java:1125)
	at com.mchange.v2.resourcepool.BasicResourcePool.access$700(BasicResourcePool.java:44)
	at com.mchange.v2.resourcepool.BasicResourcePool$ScatteredAcquireTask.run(BasicResourcePool.java:1870)
	at com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread.run(ThreadPoolAsynchronousRunner.java:696)
	[...]

These messages are due to scraping JMX metrics by Prometheus. It seems that the configuration of database connection for the metrics of database is misconfigured by Ranger.

In the ranger-admin-default-site.xml, PostgreSQL driver is used, whereas Mysql URL is used:

        <property>
                <name>ranger.jpa.audit.jdbc.dialect</name>
                <value>org.eclipse.persistence.platform.database.PostgreSQLPlatform</value>
                <description />
        </property>

        <property>
                <name>ranger.jpa.audit.jdbc.driver</name>
                <value>org.postgresql.Driver</value>
                <description />
        </property>

        <property>
                <name>ranger.jpa.audit.jdbc.url</name>
                <value>jdbc:log4jdbc:mysql://localhost/rangeraudit</value>
                <description />
        </property>