The MySQL access error on the supervisor is due to the mysql qube_readonly user having no permission to read when connecting from 'localhost'the hostname localhost, which is shorthand for "this machine".
All SQL commands in following in BLUE following are are run with the mysql client utility, which can be found at the following locations:
OS X: /usr/local/mysql/bin/mysql
Linux: /usr/bin/mysql
Windows: mysql (usually in the SEARCH path, courtesy of the Qube installation)
For the remainder of this page, if you see "mysql" in the command line, add the proper path to mysql for your particular operating system.
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The USAGE permission is effectively an empty GRANT statement, which means "no read permission", and overrides the previous permissions grant for qube_readonly from all machines.
How to fix it when logged into the supervisor
It's necessary to explictly grant the qube_readonly user read-only access from localhost by entering running the following SQL statement from on the mysql> promptsupervisor machine:
mysql -u root -e "GRANT SELECT ON *.* TO 'qube_readonly'@'localhost';"
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