[druid-user] master failed to start: not able to load mysql driver

However, I have added extensions path in config file.

“-Ddruid.extensions.directory=extensions” is added to

conf/druid/cluster/master/coordinator-overlord/jvm.config

run “bin/run-druid coordinator-overlord conf/druid/cluster/master” still failed with missing mysql msg even the mysql jar exists:

Please download a compatible library (for example ‘mysql-connector-java-5.1.48.jar’) and place it under 'extensions/mysql-metadata-storage/

its weird when I relogin aws node, seems the extensions/mysql-metadata-storage is discovered.
however, I need to manually add mysql-connector-java-5.1.48.jar to that folder,
with mysql-connector-java-5.1.48.jar + default mysql-metadata-storage-0.22.1.jar
I saw a different error:

Cannot create JDBC driver of class ‘com.mysql.jdbc.Driver’ for connect URL ‘jdbc:mycql://druid-meta.cluster-xxxxx.us-east-1.rds.amazonaws.com:3306/druid_meta’
Caused by: java.sql.SQLException: No suitable driver

at org.apache.druid.metadata.BasicDataSourceExt.createConnectionFactory(BasicDataSourceExt.java:149) ~[druid-server-0.22.1.jar:0.22.1]

at org.apache.commons.dbcp2.BasicDataSource.createDataSource(BasicDataSource.java:1897) ~[commons-dbcp2-2.0.1.jar:2.0.1]

at org.apache.commons.dbcp2.BasicDataSource.getConnection(BasicDataSource.java:1413) ~[commons-dbcp2-2.0.1.jar:2.0.1]

at org.skife.jdbi.v2.DataSourceConnectionFactory.openConnection(DataSourceConnectionFactory.java:36) ~[jdbi-2.63.1.jar:2.63.1]

at org.skife.jdbi.v2.DBI.open(DBI.java:212) ~[jdbi-2.63.1.jar:2.63.1]

… 17 more

btw: I use aws RDS mysql as DB cluster.

jdbc:mycql://druid-meta.cluster-xxxxx.us-east-1.rds.amazonaws.com:3306 is end point aws rds.

and druid_meta is db name.

“Caused by: java.sql.SQLException: No suitable driver” makes me wonder if you have the MySQL jar on all of your historicals?

this is something I have solved. thank you!