[ovirt-devel] [vdsm][maintainership] proposal for a new stable branch policy

[Milan Zamazal]

Francesco Romani <fromani at redhat.com> writes:

> Recently Milan, Petr and me discussed the state of ovirt.4.2,
> considering that release 4.2.2 is still pending and this prevents
> merging of patches in the sub-branch ovirt-4.2.
>
> We agreed we could improve the handling of the stable branch(es), in
> order to make the process smoother and more predictable.
>
>
> Currently, we avoid doing Z- branches (e.g. ovirt-4.2.2, ovirt-4.2.3...)
> as much as we can, to avoid the hassle of double-backporting patches to
> stable branch.
>
> However, if a release hits unexpected delay, this policy causes
> different hassles: the Y-branch (ovirt-4.2, ovirt-4.3) is effectively
> locked, so patches already queued
>
> and ready for next releases can't be merged and need to wait.
>
>
> The new proposed policy is the following:
>
> - we will keep working exactly as now until we hit a certain RC version.
> We choosed RC3, a rule of thumb made out of experience.

I think the idea actually was to choose the RC after which patch
acceptation is restricted (e.g. blockers only).  That would be
consistent with the problem being solved, i.e. not to block patch
merging and to clearly distinguish between patches to be merged to X.Y
only and patches to be merged to X.Y.Z.  If may typically be RC3, but I
wouldn't hard-bind the branching to a particular version.

> - if RC3 is final, everyone's happy and things resume as usual
>
> - if RC3 is NOT final, we will branch out at RC3
>
> -- from that moment on, patches for next version could be accepted on
> the Y-branch
>
> -- stabilization of the late Z version will continue on the Z-branch
>
> -- patches will be backported twice
>
>
> Example using made up numbers
>
> - We just released ovirt 4.3.1
>
> - We are working on the ovirt-4.3 branch
>
> - The last tag is v4.30.10, from ovirt-4.3 branch
>
> - We accept patches for ovirt 4.3.2 on the ovirt-4.3 branch
>
> - We keep collecting patches, until we tag v4.30.11 (oVirt 4.3.2 RC 1).
> Tag is made from ovirt-4.3 branch.
>
> - Same for tags 4.30.12 - oVirt 4.3.2 RC 2 and 4.30.13 - oVirt 4.3.2 RC
> 3. Both tags are made from ovirt-4.3 branch.
>
> - Damn, RC3 is not final. We branch out ovirt-4.3.2 form branch
> ovirt-4.3 from the same commit pointed by tag 4.30.13
>
> - Next tags (4.30.13.1) for ovirt 4.3.2 will be taken from the
> ovirt-4.3.2 branch
>
>
> I believe this approach will make predictable for everyone if and when
> the branch will be made, so when the patches could be merged and where.
>
>
> The only drawback I can see - and that I realized while writing the
> example - is the version number which can be awkward:
>
>
> v4.30.11 -> 4.3.2 RC1
>
> v4.30.12 -> 4.3.2 RC2
>
> v4.30.13 -> 4.3.2 RC3
>
> v4.30.13.1 -> 4.3.2 RC4 ?!?!
>
> v4.30.13.5 -> 4.3.2 RC5 ?!?!

Our current versions are not tied to RC versions (e.g. there can be more
than one tag per one RC), so I can see no special problem with using
v4.30.13.1 for RC4 and v4.30.13.2 for RC5.

> Perhaps we should move to four versions digit? So we could have
>
>
> v4.30.11.0 -> 4.3.2 RC1
>
> v4.30.11.1 -> 4.3.2 RC2
>
> v4.30.11.2 -> 4.3.2 RC3
>
> v4.30.11.3 -> 4.3.2 RC4
>
> v4.30.11.4 -> 4.3.2 RC5
>
>
> I don't see any real drawback in using 4-digit versions by default,
> besides a minor increase in complexity, which is balanced by more
> predictable and consistent
> versions. Plus, we already had 4-digit versions in Vdsm, so packaging
> should work just fine.
>
> Please share your thoughts,

Yedidyah Bar David <didi at redhat.com> writes:

> So the main question to ask, if you do want to keep above scheme,
> is: Do you expect, in above example, to have to tag/build vdsm for 4.3.3
> before 4.3.2 is released?

We probably want to make a new 4.3 tag as soon as one new patch is
merged to the 4.3 branch after 4.3.Z is branched out, to distinguish any
builds (private, snapshots, …) made from that.