End of support for 2LOi application links
Atlassian will no longer be supporting 2LOi application links. 2LOi links will be replaced by 3LO links.
2LOi stands for 'Two-legged OAuth with Impersonation', which is a fancy way of saying these application links allow a local server to gather data from a remote server without you logging in to the remote one. For example, your Jira Cloud dashboard could show you the build status of linked Bamboo issues in the 'Activity Stream' gadget, without you needing to log in to Bamboo first.
3LO stands for 'Three-legged OAuth', which is yet another fancy way of saying the application is linked, but the user must now log in to the remote system. For example, on the Jira Cloud dashboard that shows linked Bamboo issues, you will need to click a link to log in to Bamboo before you can see the linked issue statuses.
This change does not impact links between Jira Cloud and Confluence Cloud sites in the same domain (e.g. example.atlassian.net), which will continue to work without requiring users to log in.
When will this change happen?
2LOi links will stop working on 1st July 2018.
Why is this happening?
2LOi application links require a shared user base between the linked systems - so user 'charlie' in Jira Cloud must be the same user 'charlie' in Bamboo. This allowed you use 2LOi links to gather user data from the linked server without having to log in as that user (also known as 'impersonating' a user).
How will this affect you?
All 2LOi links will stop working and Jira Cloud admins will see a warning message similar to this after 1st July 2018:
To prevent any link issues, we recommend that Jira Cloud admins edit the local authentication type for any existing links before 1st July 2018.
Jira Cloud admins can make this change in their Jira Cloud sites by navigating to Settings > Applications > Application Links. In the Connections > Local authentication section, select OAuth from the dropdown for both the incoming and outgoing directions.