We are using JIRA 5. As on the frontend there is no mention of requirements, I tried to use the JIRA authenticator to allow users to register and log in with their JIRA accounts.
However, this fails on retrieving the account ID from the user info.
The cause of this is that as the account ID the JIRA users 'key' is used - which was introduced in JIRA 6 (to allow user renaming).
The corresponding line of the authenticator logic:
https://secure.phabricator.com/diffusion/PHU/browse/master/src/auth/PhutilAuthAdapterOAuthJIRA.php;1aa6299fcdfb31e9572d054c01afbc078b70fd7d$27
A workaround that seemed to work for us is to just use 'name' rather than 'key'.
However, one has to be aware of a migration strategy as with JIRA 6 you would want to use the key. With a manually triggered migration of the user data, getting a user by (account) name and then saving the key as the new oauth id should be sufficient.
Maybe the authenticator could be adjusted to support JIRA 5 as well as 6 at the same time?
Or maybe two authenticators could be provided, one for JIRA 5 and one for JIRA 6?