How to break a release into meaningful chunks; and put it back together again!
Author: Stephen Tweedie
The fundamental objective of the Modularity effort is to break up the monolithic concept of a “distribution release” or traditional Compose into something more fine-grained. We should be able to release applications or stacks such as LAMP or ruby-on-rails on a lifecycle that suits the application, rather than being dictated by the distribution release schedule; and we should be able to compose releases more flexibly from the various components available.
But modularity is unlikely to succeed if it requires both users and maintainers to immediately and completely discard the existing concept of Releases and Editions of Fedora. So in this document we look at how to break the traditional distribution down into a modular construction, while still preserving the ability to build the traditional releases.
This document does not try to explore how we should organise a distribution release in detail. Exact lifecycles for kernel vs. applications, for containers vs. baremetal etc. are beyond the scope here; indeed, our objective is explicitly not to assume what we need in a release, but rather to add flexibility so we can change release objectives later on. If we want Fedora Server to have a longer lifecycle than Workstation; or for Atomic to rebase docker more rapidly than Server; or for a new python to be released outside the normal distribution cycle; all these things may be possible if we have a more flexible underlying release structure. The flexibility is the subject here; planning the actual releases is a different topic.
But, ultimately we still need the well-defined concept of a release, so that all the modules we are maintaining can still come together into a well-tested, planned release on a known schedule. We also define and justify a static manifest to assign packages to modules.
Once we have parts of the distribution on different release cycles, we also have the issue of how to maintain different versions branching on different criteria and different schedules. Branching and versioning is relevant here, but is a complex topic in its own right and the topic of a future document.