[Gluster-devel] Idea: Alternate Release process

[Aravinda]

Hi,

Sharing an idea to manage multiple releases without maintaining
multiple release branches and backports.

This idea is heavily inspired by the Rust release model(you may feel
exactly same except the LTS part). I think Chrome/Firefox also follows
the same model.

http://blog.rust-lang.org/2014/10/30/Stability.html

Feature Flag:
--------------
Compile time variable to prevent compiling featurerelated code when
disabled. (For example, ./configure--disable-geo-replication
or ./configure --disable-xml etc)

Plan
-----
- Nightly build with all the features enabled(./build --nightly)

- All new patches will land in Master, if the patch belongs to a
   existing feature then it should be written behind that feature flag.

- If a feature is still work in progress then it will be only enabled in
   nightly build and not enabled in beta or stable builds.
   Once the maintainer thinks the feature is ready for testing then that
   feature will be enabled in beta build.

- Every 6 weeks, beta branch will be created by enabling all the
   features which maintainers thinks it is stable and previous beta
   branch will be promoted as stable.
   All the previous beta features will be enabled in stable unless it
   is marked as unstable during beta testing.

- LTS builds are same as stable builds but without enabling all the
   features. If we decide last stable build will become LTS release,
   then the feature list from last stable build will be saved as
   `features-release-<NUM>.yaml`, For example:
   features-release-3.9.yaml`
   Same feature list will be used while building minor releases for the
   LTS. For example, `./build --stable --features features-release-3.8.yaml`

- Three branches, nightly/master, testing/beta, stable

To summarize,
- One stable release once in 6 weeks
- One Beta release once in 6 weeks
- Nightly builds every day
- LTS release once in 6 months or 1 year, Minor releases once in 6 weeks.

Advantageous:
-------------
1. No more backports required to different release branches.(only
    exceptional backports, discussed below)
2. Non feature Bugfix will never get missed in releases.
3. Release process can be automated.
4. Bugzilla process can be simplified.

Challenges:
------------
1. Enforcing Feature flag for every patch
2. Tests also should be behind feature flag
3. New release process

Backports, Bug Fixes and Features:
----------------------------------
- Release bug fix - Patch only to Master, which will be available in
   next beta/stable build.
- Urgent bug fix - Patch to Master and Backport to beta and stable
   branch, and early release stable and beta build.
- Beta bug fix - Patch to Master and Backport to Beta branch if urgent.
- Security fix - Patch to Master, Beta and last stable branch and build
   all LTS releases.
- Features - Patch only to Master, which will be available in
   stable/beta builds once feature becomes stable.

FAQs:
-----
- Can a feature development take more than one release cycle(6 weeks)?
Yes, the feature will be enabled only in nightly build and not in
beta/stable builds. Once the feature is complete mark it as
stable so that it will be included in next beta build and stable
build.


---

Do you like the idea? Let me know what you guys think.

-- 
regards
Aravinda