Description of problem: In 3.6 it was possible to install ovirt-engine and ovirt-engine-reports. In 4.0 ovirt-engine-reports doesn't exist anymore. When migrating from el6 -> el7 or fc22 -> fc23 using backup / restore, the reports bits won't be restored after fixing bug #1340810. The only case left is in place upgrade on el7 which should be handled ensuring that the reports config left on the system doesn't break the engine.
We also need to decide if we support, or at least not prevent, running reports 3.6 on a separate machine. If so, we need to keep [1]. I'd say we probably want two questions: 1. oVirt Reports was found set up on this machine. Reports is not available in oVirt 4.0. Remove it? 2. The engine is configured to access oVirt Reports on {url}. Reports is not available in oVirt 4.0. Remove this configuration? For (2.), we can add logic to check if it's on same or different machine (will be ugly, because we do not have REPORTS_FQDN, so will have to parse ENGINE_REPORTS_BASE_URL), and/or try to GET it and see if this succeeded. Or do nothing and let the user decide. [1] /etc/ovirt-engine/engine.conf.d/10-setup-reports-access.conf
In a private discussion Yaniv decided to remove this file as well. This means that running 3.6 reports against a 4.0 engine is not forbidden, but any connection between them, including sso, is.