How to connect jira to other web application for user management. I dont want to manage users inJIRA

[Abhay Mudawadkar]

My web application has arround 2000 users,now we would like to use JIRA for issue management. But we don't want to maintain any user in JIRA. By any means is it possible in JIRA to connect our user database or by Rest service and do the user validation.
Current web application manages the user simply through database.

[Nic Brough -Adaptavist-]

The best way to do this would be to expose your "user database" to Jira as though it is another directory.  Does this database have any way to present itself as an AD or LDAP directory?  Could you set up a simple LDAP server based on it?

If that's not going to work, then you'll need to write an authenticator add-on for Jira and replace its internal one.