View source for User Services/Sync/Transition To FxA Sync

A summary of the transition from Legacy Sync -> FxA Sync in Fx29. A decision was made on 1/8/14. Those in attendance of the decision:

* Johnathan Nightingale 
* Mark Mayo
* Toby Elliot
* John Gruen
* Ryan Feeley
* Madhava Enros
* Ian Barlow
* Chris Karlof
* Chad Weiner
* Gavin Sharp
* Mark Finkle
* Tauni Oxborrow
* Edwin Wong
* Robert Lord

== Legacy Sync Users ==
* For users that have a browser profile that is already connected to Legacy Sync, Legacy Sync will continue to work when they upgrade to Fx29. There will be no upsell to FxA Sync, and no attempt to transition them to FxA Sync in Fx29. Just let 'em be. In Fx29, these users will see little to no evidence of FxA Sync without disconnecting from Legacy Sync first.
* These users will not see the marketing information about FxA and Sync in the "walkthrough" shown in Fx29 update.
* At various UI points in Fx29, we will provide users connected to Legacy Sync with a link to a SUMO page providing details about the transition and future plans. 
* Legacy Sync users can continue to connect new browsers to Legacy Sync on Fx28 and below.
* Legacy Sync users *will not* be able to connect new browsers to Legacy Sync on Fx29+. The login screen for FxA Sync will provide a link to a SUMO page providing further information for users trying to do this (i.e., options are install Fx28 or below or upgrade all your devices to Fx29 and use FxA Sync). 
* New Legacy Sync accounts can be created on Fx28 and below, but not on Fx29+.
* We have to transition these users to FxA Sync eventually, but we'll do this more thoughtfully in Fx30+, particularly for users with only a single device connected to Legacy Sync.
* EOL for Legacy Sync is proposed to be Fx31.

== FxA Sync Users (i.e., new Sync users) ==
* For users that do not have a browser profile connected to Legacy Sync, they will see marketing information about FxA and Sync in the "walkthrough" shown in the Fx29 update.
* All Sync UI entry points will take users through FxA Sync create account/login flow.

== Future proofing == 
* We lay what technical groundwork we can for a future sunset date, e,g, deprecation messaging channels.
* We lay what technical groundwork we can for future transition strategies and upsells, e.g., starting to record the Firefox version of connected sync clients.
* Tracking here: https://bugzilla.mozilla.org/show_bug.cgi?id=956445

== Sync Server ==
* There will be two DBs: Sync 1.1 (Legacy) and Sync 1.5 (FxA) will point at different DBs
* Sync 1.5 will require Fx29.

== Channels ==
* Feature will be on and enabled in Nightly/Aurora/Beta
* Jonath: No guarantees on pre-release channels
* Finkle: Lots of Fennec users use Nightly 

== Custom Servers ==
* In general, Custom Server support for FxA Sync in Fx29 be somewhere between a "non-goal" and "best effort"
* If you're already connected to Sync, then in Fx29, your set up should continue to work.
* Otherwise, it is subject to other above restrictions for Legacy Sync users. 
* Custom servers should in theory be possible with FxA Sync, but with a different architecture (Token server + Sync 1.5).