An ident-service is not mandatory. If such a service is running on the client's host however, most irc servers will use this to query the username of the connecting client, and use the result for the user@host.tld part of the online identity.
If there is no ident-service however, most irc servers will use whatever name the client provided as <username> when sending the "USER" command during registration. The value eggdrop sends during registration is controlled by the username setting.
If you'd like to install an ident-service on your system, install the appropriate package using yum or any other package manager (I would generally recommend oidentd or identd)
The lack of any other errors would suggest that your eggdrop is not able to open the config-file. Did you change anything since you got your eggdrop up'n'running? If you edited your config-file, have you double-checked the file ownership and permissions (file owned by overwatch and user has read-permissions at a minimum)?