Thanks to everyone who chimed in. To Gilbert's questions, I think that's outside the territory of what a policy or guidelines will cover, and will be up to the judgement of the committer.
My initial search for "backport" was insufficient and I missed the following existing comment in a different section of versioning.md lays out a policy of only critical issues: <start quote> At any given time, 3 releases are supported: ... Support means fixing of critical issues that affect the release. Once an issue is deemed critical, it will be fixed in only those affected releases that are still supported. ... Which issues are considered critical? Security fixes Compatibility regressions Functional regressions Performance regressions Fixes for 3rd party integration (e.g., Docker remote API) Whether an issue is considered critical or not is sometimes subjective. In some cases it is obvious and sometimes it is fuzzy. Users should work with committers to figure out the criticality of an issue and get agreement and commitment for support. <end quote> >From the discussion here, it sounds like we should add the guidelines similar to what Greg suggested above to clarify that there's some subjectivity here, as well as keeping some of the clear cases (like what the existing documentation does). I can send out a change sometime soon. On Wed, Jul 18, 2018 at 10:37 AM, Gilbert Song <gilb...@mesosphere.io> wrote: > Thanks for clarifying the backporting policy, BenM! > > I totally agree with the changes proposed for the backporting policy, but > I realize two more scenarios that are more clear to me yet: > > - There are some bugs that are not fixable (due to legacy technical > decisions), and we end up with fixing the issue by a semantic/behavior > change in a new release. Do we expect this semantic/behavior change being > backported? > - There might be some bugs that root cause is unknown yet, but it did > impact on a couple releases. If we decide to add some commits for debugging > purpose (e.g., a new debugging endpoint, or more logging), should we also > allow these patches to be backported? > > For #2, I think we should do the backporting, but for #1, maybe more > discussion is needed since it relates to whether the user has to upgrade or > not. > > Cheers, > Gilbert > > On Tue, Jul 17, 2018 at 4:26 PM, Lawrence Rau <larry...@mac.com> wrote: > >> I don’t have a big stake in, however, one opinion is if a large >> commercial enterprise was using a specific release that is working the >> desire is often to only upgrade if necessary. Necessary can be for a >> number of reasons including new features; however if a new feature is not >> needed the compelling reason to upgrade is to fix a specific problem that >> is causing issues. Thus keeping a maintenance release stable is very >> important and reducing the chance for, while fixing one problem, >> introducing another. >> >> Often a clear classification of severity of the problem would dictate the >> need to make a change. (yes these can be subjective, but some guidance >> would be better than nothing). >> >> It might be good to give committers guidance on back porting things that >> have a high impact on improving a problem. Fixing a crashing bug, fixing a >> degenerative performance issue, etc, where these issues have no easy/viable >> work around. Nice to have fixes aren’t, always, worth updating to. >> >> There can be an argument to respond with a “then don’t upgrade” but if >> changing the release with “nice to have’s” and several point releases later >> when a critical bug is fixed then the org if forced to accept the risk of >> the nice to have’s. >> >> just an opinion. >> …larry >> >> >> On Jul 17, 2018, at 3:00 PM, Chun-Hung Hsiao <chhs...@mesosphere.io> >> wrote: >> >> I just have a comment on a special case: >> If a fix for a flaky test is easy to backport, >> IMO we probably should backport it, >> otherwise if someone backports another critical fix in the future, >> it would take them extra effort to check all CI failures. >> >> On Mon, Jul 16, 2018 at 11:39 AM Vinod Kone <vinodk...@apache.org> wrote: >> >>> I like how you summarized it Greg and I would vote for leaving the >>> decision >>> to the committer too. In addition to what others mentioned, I think >>> committer should've the responsibility because if things break in a point >>> release (after it is released), it is the committer and contributor who >>> are >>> on the hook to triage and fix it and not the release manager. >>> >>> Having said that, if "during" the release process (i.e., cutting an RC) >>> these backports cause delays for a release manager in getting the release >>> out (e.g., CI flakiness introduced due to backports), release manager >>> could >>> be the ultimate arbiter on whether such a backport should be reverted or >>> fixed by the committer/contributor. Hopefully such issues are caught much >>> before a release process is started (e.g., CI running against release >>> branches). >>> >>> On Mon, Jul 16, 2018 at 1:28 PM Jie Yu <yujie....@gmail.com> wrote: >>> >>> > Greg, I like your idea of adding a prescriptive "policy" when >>> evaluating >>> > whether a bug fix should be backported, and leave the decision to >>> committer >>> > (because they have the most context, and avoid a bottleneck in the >>> > process). >>> > >>> > - Jie >>> > >>> > On Mon, Jul 16, 2018 at 11:24 AM, Greg Mann <g...@mesosphere.io> >>> wrote: >>> > >>> > > My impression is that we have two opposing schools of thought here: >>> > > >>> > > 1. Backport as little as possible, to avoid unforeseen >>> consequences >>> > > 2. Backport as much as proves practical, to eliminate bugs in >>> > > supported versions >>> > > >>> > > Do other people agree with this assessment? >>> > > >>> > > If so, how can we find common ground? One possible solution would be >>> to >>> > > leave the decision on backporting up to the committer, without >>> > specifying a >>> > > project-wide policy. This seems to be the status quo, and would lead >>> to >>> > > some variation across committers regarding what types of fixes are >>> > > backported. We could also choose to delegate the decision to the >>> release >>> > > manager; I favor leaving the decision with the committer, to >>> eliminate >>> > the >>> > > burden on release managers. >>> > > >>> > > Here's a thought: rather than defining a prescriptive "policy" that >>> we >>> > > expect committers to abide by, we could enumerate in the >>> documentation >>> > the >>> > > competing concerns that we expect committers to consider when making >>> > > decisions on backports. The committing docs could read something >>> like: >>> > > >>> > > "When bug fixes are committed to master, the committer should >>> evaluate >>> > the >>> > > fix to determine whether or not it should be backported to supported >>> > > versions. This is left to the committer, but they are expected to >>> weigh >>> > the >>> > > following concerns when making the decision: >>> > > >>> > > - Every backported change comes with a risk of unintended >>> > > consequences. The change should be carefully evaluated to ensure >>> that >>> > such >>> > > side-effects are highly unlikely. >>> > > - As the complexity of applying a backport increases due to merge >>> > > conflicts, the likelihood of unintended consequences also >>> increases. >>> > Bug >>> > > fixes which require extensive rebasing should only be backported >>> when >>> > the >>> > > bug is critical enough to warrant the risk. >>> > > - Users of supported versions benefit greatly from the resolution >>> of >>> > > bugs in point releases. Thus, whenever concerns #1 and #2 can be >>> > allayed >>> > > for a given bug fix, it should be backported." >>> > > >>> > > >>> > > Cheers, >>> > > Greg >>> > > >>> > > >>> > > On Mon, Jul 16, 2018 at 3:06 AM, Alex Rukletsov <a...@mesosphere.com >>> > >>> > > wrote: >>> > > >>> > >> Back porting as little as possible is the ultimate goal for me. My >>> > >> reasons are closely aligned with what Andrew wrote above. >>> > >> >>> > >> If we agree on this strategy, the next question is how to enforce >>> it. My >>> > >> intuition is that committers will lean towards back porting their >>> > patches >>> > >> in arguable cases, because humans tend to overestimate the >>> importance of >>> > >> their personal work. Delegating the decision in such cases to a >>> release >>> > >> manager in my opinion will help us enforce the strategy of minimal >>> > number >>> > >> backports. As a bonus, the release manager will have a much better >>> > >> understanding of what's going on with the release, keyword: "more >>> > >> ownership". >>> > >> >>> > >> On Sat, Jul 14, 2018 at 12:07 AM, Andrew Schwartzmeyer < >>> > >> and...@schwartzmeyer.com> wrote: >>> > >> >>> > >>> I believe I fall somewhere between Alex and Ben. >>> > >>> >>> > >>> As for deciding what to backport or not, I lean toward Alex's view >>> of >>> > >>> backporting as little as possible (and agree with his criteria). My >>> > >>> reasoning is that all changes can have unforeseen consequences, >>> which I >>> > >>> believe is something to be actively avoided in already released >>> > versions. >>> > >>> The reason for backporting patches to fix regressions is the same >>> as >>> > the >>> > >>> reason to avoid backporting as much as possible: keep behavior >>> > consistent >>> > >>> (and safe) within a release. With that as the goal of a branch in >>> > >>> maintenance mode, it makes sense to fix regressions, and make >>> > exceptions to >>> > >>> fix CVEs and other critical/blocking issues. >>> > >>> >>> > >>> As for who should decide what to backport, I lean toward Ben's >>> view of >>> > >>> the burden being on the committer. I don't think we should add more >>> > work >>> > >>> for release managers, and I think the committer/shepherd obviously >>> has >>> > the >>> > >>> most understanding of the context around changes proposed for >>> backport. >>> > >>> >>> > >>> Here's an example of a recent bugfix which I backported: >>> > >>> https://reviews.apache.org/r/67587/ (for MESOS-3790) >>> > >>> >>> > >>> While normally I believe this change falls under "avoid due to >>> > >>> unforeseen consequences," I made an exception as the bug was old, >>> circa >>> > >>> 2015, (indicating it had been an issue for others), and was causing >>> > >>> recurring failures in testing. The fix itself was very small, >>> meaning >>> > it >>> > >>> was easier to evaluate for possible side effects, so I felt a >>> little >>> > safer >>> > >>> in that regard. The effect of not having the fix was a fatal and >>> > undesired >>> > >>> crash, which furthermore left troublesome side effects on the >>> system >>> > (you >>> > >>> couldn't bring the agent back up). And lastly, a dependent project >>> > (DC/OS) >>> > >>> wanted it in their next bump, which necessitated backporting to the >>> > release >>> > >>> they were pulling in. >>> > >>> >>> > >>> I think in general we should backport only as necessary, and leave >>> it >>> > on >>> > >>> the committers to decide if backporting a particular change is >>> > necessary. >>> > >>> >>> > >>> >>> > >>> On 07/13/2018 12:54 am, Alex Rukletsov wrote: >>> > >>> >>> > >>>> This is exactly where our views differ, Ben : ) >>> > >>>> >>> > >>>> Ideally, I would like a release manager to have more ownership and >>> > less >>> > >>>> manual work. In my imagination, a release manager has more power >>> and >>> > >>>> control about dates, features, backports and everything that is >>> > related >>> > >>>> to >>> > >>>> "their" branch. I would also like us to back port as little as >>> > >>>> possible, to >>> > >>>> simplify testing and releasing patch versions. >>> > >>>> >>> > >>>> On Fri, Jul 13, 2018 at 1:17 AM, Benjamin Mahler < >>> bmah...@apache.org> >>> > >>>> wrote: >>> > >>>> >>> > >>>> +user, I probably it would be good to hear from users as well. >>> > >>>>> >>> > >>>>> Please see the original proposal as well as Alex's proposal and >>> let >>> > us >>> > >>>>> know >>> > >>>>> your thoughts. >>> > >>>>> >>> > >>>>> To continue the discussion from where Alex left off: >>> > >>>>> >>> > >>>>> > Other bugs and significant improvements, e.g., performance, >>> may be >>> > >>>>> back >>> > >>>>> ported, >>> > >>>>> the release manager should ideally be the one who decides on >>> this. >>> > >>>>> >>> > >>>>> I'm a little puzzled by this, why is the release manager >>> involved? As >>> > >>>>> we >>> > >>>>> already document, backports occur when the bug is fixed, so this >>> > >>>>> happens in >>> > >>>>> the steady state of development, not at release time. The release >>> > >>>>> manager >>> > >>>>> only comes in at the time of the release itself, at which point >>> all >>> > >>>>> backports have already happened and the release manager handles >>> the >>> > >>>>> release >>> > >>>>> process. Only blocker level issues can stop the release and >>> while the >>> > >>>>> release manager has a strong say, we should generally agree on >>> what >>> > >>>>> consists of a release blocking issue. >>> > >>>>> >>> > >>>>> Just to clarify my workflow, I generally backport every bug fix I >>> > >>>>> commit >>> > >>>>> that applies cleanly, right after I commit it to master (with the >>> > >>>>> exceptions I listed below). >>> > >>>>> >>> > >>>>> On Thu, Jul 12, 2018 at 8:39 AM, Alex Rukletsov < >>> a...@mesosphere.com >>> > > >>> > >>>>> wrote: >>> > >>>>> >>> > >>>>> > I would like to back port as little as possible. I suggest the >>> > >>>>> following >>> > >>>>> > criteria: >>> > >>>>> > >>> > >>>>> > * By default, regressions are back ported to existing release >>> > >>>>> branches. A >>> > >>>>> > bug is considered a regression if the functionality is present >>> in >>> > the >>> > >>>>> > previous minor or patch version and is not affected by the bug >>> > there. >>> > >>>>> > >>> > >>>>> > * Critical and blocker issues, e.g., a CVE, can be back ported. >>> > >>>>> > >>> > >>>>> > * Other bugs and significant improvements, e.g., performance, >>> may >>> > be >>> > >>>>> back >>> > >>>>> > ported, the release manager should ideally be the one who >>> decides >>> > on >>> > >>>>> this. >>> > >>>>> > >>> > >>>>> > On Thu, Jul 12, 2018 at 12:25 AM, Vinod Kone < >>> vinodk...@apache.org >>> > > >>> > >>>>> wrote: >>> > >>>>> > >>> > >>>>> > > Ben, thanks for the clarification. I'm in agreement with the >>> > >>>>> points you >>> > >>>>> > > made. >>> > >>>>> > > >>> > >>>>> > > Once we have consensus, would you mind updating the doc? >>> > >>>>> > > >>> > >>>>> > > On Wed, Jul 11, 2018 at 5:15 PM Benjamin Mahler < >>> > >>>>> bmah...@apache.org> >>> > >>>>> > > wrote: >>> > >>>>> > > >>> > >>>>> > > > I realized recently that we aren't all on the same page >>> with >>> > >>>>> > backporting. >>> > >>>>> > > > We currently only document the following: >>> > >>>>> > > > >>> > >>>>> > > > "Typically the fix for an issue that is affecting supported >>> > >>>>> releases >>> > >>>>> > > lands >>> > >>>>> > > > on the master branch and is then backported to the release >>> > >>>>> branch(es). >>> > >>>>> > In >>> > >>>>> > > > rare cases, the fix might directly go into a release branch >>> > >>>>> without >>> > >>>>> > > landing >>> > >>>>> > > > on master (e.g., fix / issue is not applicable to >>> master)." [1] >>> > >>>>> > > > >>> > >>>>> > > > This leaves room for interpretation about what lies >>> outside of >>> > >>>>> > "typical". >>> > >>>>> > > > Here's the simplest way I can explain what I stick to, and >>> I'd >>> > >>>>> like >>> > >>>>> to >>> > >>>>> > > hear >>> > >>>>> > > > what others have in mind: >>> > >>>>> > > > >>> > >>>>> > > > * By default, bug fixes at any level should be backported >>> to >>> > >>>>> existing >>> > >>>>> > > > release branches if it affects those releases. Especially >>> > >>>>> important: >>> > >>>>> > > > crashes, bugs in non-experimental features. >>> > >>>>> > > > >>> > >>>>> > > > * Exceptional cases that can omit backporting: difficult to >>> > >>>>> backport >>> > >>>>> > > fixes >>> > >>>>> > > > (especially if the bugs are deemed of low priority), bugs >>> in >>> > >>>>> > experimental >>> > >>>>> > > > features. >>> > >>>>> > > > >>> > >>>>> > > > * Exceptional non-bug cases that can be backported: >>> performance >>> > >>>>> > > > improvements. >>> > >>>>> > > > >>> > >>>>> > > > I realize that there is a ton of subtlety here (even in >>> terms >>> > of >>> > >>>>> which >>> > >>>>> > > > things are defined as bugs). But I hope we can lay down a >>> > policy >>> > >>>>> that >>> > >>>>> > > gives >>> > >>>>> > > > everyone the right mindset for common cases and then >>> discuss >>> > >>>>> corner >>> > >>>>> > cases >>> > >>>>> > > > on-demand in the future. >>> > >>>>> > > > >>> > >>>>> > > > [1] http://mesos.apache.org/docume >>> ntation/latest/versioning/ >>> > >>>>> > > > >>> > >>>>> > > >>> > >>>>> > >>> > >>>>> >>> > >>>>> >>> > >>> >>> > >> >>> > > >>> > >>> >> >> >
