Keystone uses its own database to store identity information and metadata. There might be situations where the Keystone database has connection errors. For example, consider a situation where your Keystone service is running, however, when any of the Keystone commands are invoked, it hangs. The Keystone log file shows error messages with DBConnectionError.  

In such cases, make sure that the MySQL database is up and running and is accessible using the address and port specified in the keystone.conf file. This configuration file has a [database] section, which specifies the connection string:

[database]
connection = mysql://keystone:[email protected]/keystone 

You can manually test the connection to the Keystone MySQL database using the mysql command. This will prompt you for a password for the specified user. Once you are able to connect to the database and run a simple show tables command on the prompt, you can ensure that the database is up and running properly:

# mysql -u <username> -p -h <hostname> keystone

If the show tables command returns empty, it indicates that the Keystone database does not have any tables created. In this case, we can initialize the database using the keystone-manage command. This will create all the required tables in the database and the Keystone service will be able to insert new records into it:

# keystone-manage db_sync

The previous techniques cover only a handful of issues that may occur with the Keystone service. The keystone.log file is the key resource for identifying different failures, and appropriate tools must be used to troubleshoot the respective problems.

Lets now see how we can troubleshoot the OpenStack Image service.