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From Remi Bergsma <>
Subject Re: Blameless post mortem
Date Mon, 28 Sep 2015 12:09:15 GMT
Dude, this is the final friendly email about his. All points have been made in previous mails.
This has nothing to do with ‘blameless’ and ‘learning’ anymore.

Read Seb’s mail. We will move on now.

Regards, Remi

On 28/09/15 13:54, "Bharat Kumar" <> wrote:

>Hi Remi,
>Whatever  ever we think  we have discovered are all well known best practices while developing
code in community. 
>I agree that tests need to be run on a new PR,  but i wonder why was this ignored when
merging the VR refactor code. Perhaps we will uncover some more issues if we investigate this.
I believe 
>one of the reasons for this is the complexity and incomplete nature of the vr refactor
change and failing to identify the areas which got effected. If we had a good documentation
i think we cloud have understood the areas that were getting 
>impacted early on, areas like the vpn ,  iptables, isolated networks rvr   etc  and run
the relevant tests. The documentation will also help us focus on these areas while reviewing
 and fixing subsequent issues. Currently no one knows the areas that got effected 
>due to the vr refactor change, we are seeing issues all over the code.  I think this is
a bigger problem than what we have discussed so far.
>I think presently we should stop fixing all the vr refactoring  bugs until we come up
with a  proper document describing the VR refactoring  changes.
>I am not suggesting that we should revert the vr refactor code, I am willing to work on
this and fix the issues,  I am only asking if we can get some documentation.
>On 28-Sep-2015, at 4:59 pm, Sebastien Goasguen <> wrote:
>>> On Sep 28, 2015, at 1:14 PM, Remi Bergsma <>
>>> Hi Bharat,
>>> There is only one way to prove a feature works: with tests. That’s why I say
actually _running_ the tests we have today on any new PR, is the most important thing. Having
no documentation is a problem, I agree, but it is not more important IMHO. If we had the documentation,
we still would have issues if nobody runs the tests and verifies pull requests. Documentation
that is perfect does not automatically lead to perfect implementation. So we need tests to
>>> If we don’t agree that is also fine. We need to do both anyway and I think
we do agree on that.
>> Also we need to move forward. We should have a live chat once 4.6 is out to discuss
all issues/problems and iron out the process.
>> But reverting the VR refactor is not going to happen. There was ample discussions
on the PR when it was submitted, there was time to review and raise concerns at that time.
It went through quite a few reviews, tests etc…Maybe the documentation is not good, but
the time to raise this concern I am afraid was six months ago. We can learn from it, but we
are not going to revert it, this would not go cleanly as David mentioned.
>> So let’s get back to blockers for 4.6, are there still VR related issues with master
>>> Regards,
>>> Remi
>>> On 28/09/15 12:15, "Bharat Kumar" <> wrote:
>>>> Hi Remi,
>>>> i do not agree with “There is no bigger problem”  part of your reply.
so I had to repeat myself to make it more clear, Not because i am not aware of what this thread
is supposed to do.
>>>> Regards,
>>>> Bharat.
>>>> On 28-Sep-2015, at 2:51 pm, Remi Bergsma <>
>>>>> Hi Bharat,
>>>>> I understand your frustrations but we already agreed on this so no need
to repeat. This thread is supposed to list some improvements and learn from it. Your point
has been taken so let’s move on.
>>>>> We need documentation first, then do a change after which all tests should
pass. Even better is we write (missing) tests before changing stuff so you know they pass
before and after the fact. 
>>>>> When doing reviews, feel free to ask for design documentation if you
feel it is needed.
>>>>> Regards, Remi
>>>>> On 28/09/15 11:02, "Bharat Kumar" <> wrote:
>>>>>> Hi Remi,
>>>>>> I never intended to say that we should not run tests, but even before
tests we should have proper documentation. My concern was if a major change is being introduced
it should be properly documented. All the issues which we are trying to fix are majorly due
to VR refactor. If there was a proper documentation for this we could
>>>>>> have fixed this in a better way.  Even to add tests we need to understand
how a particular thing works and what data dose it expect. I think while fixing the python
based code changes this is where most of the people are facing issues. A proper documentation
will help in understanding these in a better way.
>>>>>> Thanks,
>>>>>> Bharat.
>>>>>> On 28-Sep-2015, at 1:57 pm, Remi Bergsma <>
>>>>>>> Hi Bharat,
>>>>>>> There is no bigger problem. We should always run the tests and
if we find a case that isn’t currently covered by the tests we should simply add tests for
it. There’s no way we’ll get a stable master without them. The fact that they may not
cover everything, is no reason to not rely on them. If a feature is not important enough to
write a test for, then the feature is probably not important anyway. And if it is, then add
a test :-)
>>>>>>> I do agree on the design documentation requirement for any (major?)
change. I found some design documentations on the subject you mention, but it should have
been more detailed. 
>>>>>>> Regards,
>>>>>>> Remi
>>>>>>> On 28/09/15 09:58, "Bharat Kumar" <>
>>>>>>>> Hi Remi,
>>>>>>>> Thank you for the Blame less postmortem. 
>>>>>>>> I think there is a bigger problem here than just the review
process and running tests. Even if we run the tests we cannot be sure that every thing will
work as intended. The tests will only give some level of confidence. The tests may not cover
all the use cases.
>>>>>>>> I think the problem here is that the way major changes to
the code base are dealt with. For example,  VR refactoring was done without discussing the
design implications and the amount of changes it would bring in. I could not find any design
document. The vr refactor changed a lot of code and the way VR used to work and in my opinion
it was incomplete-vpn, isolated networks, basic networks, iptable rules and rvr in isolated
case etc were not implemented. Most of us are still in the process of understanding this.
Even before reaching this state we had to spend a lot of time fixing issues mentioned in the
thread [Blocker/Critical] VR related Issues.  
>>>>>>>> When a change of this magnitude is being made, we should
call out all the changes and document them properly. This will help people to create better
fixes. Currently when we attempt to fix the isolated vr case it is effecting the vpc and vice
versa. for example pr 738 fixed it for vpc networks but broke it for isolated case. I believe
it is not too late to at least start documenting the changes now.
>>>>>>>> Thanks,
>>>>>>>> Bharat.
>>>>>>>> On 28-Sep-2015, at 10:52 am, Sanjeev N <>
>>>>>>>>> I have a concern here. Some of us are actively involved
in reviewing the
>>>>>>>>> PRs related to marvin tests(Enhancing existing tests/Adding
new tests). If
>>>>>>>>> we have to test a PR it requires an environment to be
created with actual
>>>>>>>>> resources and this is going to take lot of time. Some
of the tests can run
>>>>>>>>> on simulator but most of the tests require real hardware
to test. PR
>>>>>>>>> submitter is already testing and submitting the test
results along with the
>>>>>>>>> PR. So is it require to test these PRs by reviewers?
>>>>>>>>> On Sat, Sep 26, 2015 at 1:49 PM, sebgoa <>
>>>>>>>>>> Remi, thanks for the detailed post-mortem, it's a
good read and great
>>>>>>>>>> learning.
>>>>>>>>>> I hope everyone reads it.
>>>>>>>>>> The one thing to emphasize is that we now have a
very visible way to get
>>>>>>>>>> code into master, we have folks investing time to
provide review (great),
>>>>>>>>>> we need the submitters to make due diligence and
answer all comments in the
>>>>>>>>>> reviews.
>>>>>>>>>> In another project i work on, nothing can be added
to the code without
>>>>>>>>>> unit tests. I think we could go down the route of
asking for new
>>>>>>>>>> integration tests and unit tests for anything. If
not, the PR does not get
>>>>>>>>>> merged. But let's digest your post-mortem and we
can discuss after 4.6.0.
>>>>>>>>>> I see that you reverted one commit that was not made
by you, that's great.
>>>>>>>>>> Let's focus on the blockers now, everything else
can wait.
>>>>>>>>>> The big bonus of doing what we are doing is that
once 4.6.0 is out, we can
>>>>>>>>>> merge PRs again (assuming they are properly rebased
and tested) and we can
>>>>>>>>>> release 4.6.1 really quickly after.
>>>>>>>>>> -sebastien
>>>>>>>>>> On Sep 25, 2015, at 9:51 PM, Remi Bergsma <>
>>>>>>>>>> wrote:
>>>>>>>>>>> Hi all,
>>>>>>>>>>> This mail is intended to be blameless. We need
to learn something from
>>>>>>>>>> it. That's why I left out who exactly did what because
it’s not relevant.
>>>>>>>>>> There are multiple examples but it's about the why.
Let's learn from this
>>>>>>>>>> without blaming anyone.
>>>>>>>>>>> We know we need automated testing. We have integration
tests, but we are
>>>>>>>>>> unable to run all of them on any Pull Request we
receive. If we would have
>>>>>>>>>> that in place, it'd be much easier to spot errors,
regression and so on.
>>>>>>>>>> It'd also be more rewarding to write more tests.
>>>>>>>>>>> Unfortunately we're not there yet. So, we need
to do something else
>>>>>>>>>> instead until we get there. If we do nothing, we
know we have many issues
>>>>>>>>>> because a master that breaks on a regular basis is
the most frustrating
>>>>>>>>>> things. We said we'd use Pull Requests with at least
two humans to review
>>>>>>>>>> and give their OK for a Pull Request. In the form
of LGTM: Looks Good To
>>>>>>>>>> Me. Ok, so the LGTMs are there because we have no
automated testing. Keep
>>>>>>>>>> that in mind. You are supposed to replace automated
testing until it's
>>>>>>>>>> there.
>>>>>>>>>>> Since we do this, master got a lot more stable.
But every now and then
>>>>>>>>>> we still have issues. Let's look at how we do manual
reviews. Again, this
>>>>>>>>>> is not to blame anyone. It's to open our eyes and
make us realise what
>>>>>>>>>> we're doing and what results we get out of that.
>>>>>>>>>>> Example Pull Request #784:
>>>>>>>>>>> Title: CLOUDSTACK-8799 fixed the default routes
>>>>>>>>>>> That's nice, it has a Jira id and a short description
(as it should be).
>>>>>>>>>>> The first person comes along and makes a comment:
>>>>>>>>>>> "There was also an issue with VPC VRs" ... "Have
you seen this issue?
>>>>>>>>>> Does your change affects the VPC VR (single/redundant)?"
>>>>>>>>>>> Actually a good question. Unfortunaly there comes
no answer. After a
>>>>>>>>>> reminder, it was promised to do tests against VPC
networks. Great!
>>>>>>>>>>> The Jenkins builds both succeed and also Travis
is green. But how much
>>>>>>>>>> value does this have? They have the impression to
do automated testing, and
>>>>>>>>>> although you could argue they do, it's far from complete.
If it breaks, you
>>>>>>>>>> know you have an issue. But it doesn’t work the
other way around.
>>>>>>>>>>> Back to our example PR. In the mean time, another
commit gets pushed to
>>>>>>>>>> it: "CLOUDSTACK-8799 fixed for vpc networks." But
if you look at the Jira
>>>>>>>>>> issue, you see it is about redundant virtual routers.
The non-VPC ones. So
>>>>>>>>>> this is vague at best. But a reviewer gives a LGTM
because the person could
>>>>>>>>>> create a VPC. That doesn't have anything to do with
the problem being fixed
>>>>>>>>>> in this PR nor with the comments made earlier. But,
at least the person
>>>>>>>>>> said what he did and we should all do that. What
nobody knew back then, was
>>>>>>>>>> that this broke the default route on VPCs.
>>>>>>>>>>> Then something strange happens: the two commits
from the PR end up on
>>>>>>>>>> master as direct commits. With just one LGTM and
no verification from the
>>>>>>>>>> person commenting about the linked issue. This happened
on Friday September
>>>>>>>>>> 11th.
>>>>>>>>>>> That day 21 commits came in, from 7 Pull Request
and unfortunately also
>>>>>>>>>> from some direct commits. We noticed the direct commits
and notified the
>>>>>>>>>> list (
As a lot
>>>>>>>>>> came in at the same time, it was decided not to revert
them. Looking back,
>>>>>>>>>> we should have done it.
>>>>>>>>>>> From this point on, VPCs were broken as they
wouldn't get a default
>>>>>>>>>> route. So, no public internet access from VMs in
VPC tiers, no VPNs
>>>>>>>>>> working, etc. This was mentioned to the list on Thursday
September 15th,
>>>>>>>>>> after some chats and debugging going on over the
weekend (
>>>>>>>>>>> Here we are, master is broken functionality wise
and new Pull Requests
>>>>>>>>>> come in to fix blockers. But we cannot ever test
their proper working,
>>>>>>>>>> because VPCs are broken in master and so also in
the PRs branched off of
>>>>>>>>>> it. With or without change in the PR.
>>>>>>>>>>> It starts to escalate as the days go by.
>>>>>>>>>>> I’ll leave out the bit on how this frustrated
people. Although it’s good
>>>>>>>>>> to know we do not want to be in this situation.
>>>>>>>>>>> Eventually Wilder and I spent an evening and
a day working on a branch
>>>>>>>>>> where we loaded 7 PRs on top of each other (all VR
related) only to find
>>>>>>>>>> the VPC is still broken. It allowed us to zoom in
and find the default
>>>>>>>>>> route was missing again. We said it worked 3 weeks
before, because the same
>>>>>>>>>> tests that succeeded then, now were broken. We had
already fixed this in PR
>>>>>>>>>> #738 on August 25 so were sure about it.
>>>>>>>>>>> After some digging we could trace it back to
Pull Request #784. Imagine
>>>>>>>>>> the feeling seeing your own comment there mentioning
the previous issue on
>>>>>>>>>> the default gateways. Fair to say our human review
process clearly failed
>>>>>>>>>> here. Many many hours were spent on this problem
over the past two weeks.
>>>>>>>>>> Could we have prevented this from happening? I think
so, yes.
>>>>>>>>>>> This example clearly shows why:
>>>>>>>>>>> - we should use Pull Requests
>>>>>>>>>>> It made the change visible: Great!
>>>>>>>>>>> - we do reviews and ask for feedback
>>>>>>>>>>> We got feedback and questions: Also great!
>>>>>>>>>>> - we should always respond to feedback and verify
it is resolved, before
>>>>>>>>>> merging
>>>>>>>>>>> We need to improve here. Even with two reviewers
that say LGTM, we
>>>>>>>>>> should still address any feedback before merging.
>>>>>>>>>>> - we should have two humans doing a review
>>>>>>>>>>> We need to improve here as well. Not one reviewer,
we need two. Really.
>>>>>>>>>>> - we need to document why we say LGTM.
>>>>>>>>>>> Another improvement. It’s nice to say LGTM,
but a review of only 4
>>>>>>>>>> characters and nothing more is useless. We need to
know what was tested and
>>>>>>>>>> how. Test results, screen shots or anything that
shows what's been
>>>>>>>>>> verified. If you only reviewed the code, also fine
but at least say that.
>>>>>>>>>> Then the next reviewer should do another type of
review to get the comlete
>>>>>>>>>> picture. Remember you're replacing automated testing!
>>>>>>>>>>> - we should always merge Pull Requests
>>>>>>>>>>> We made it easy, merging is the de facto standard,
and it has even more
>>>>>>>>>> benefits. You can trace commits back to their Pull
Request (and find all
>>>>>>>>>> comments and discussion there: saves time, trust
me). It also allows for
>>>>>>>>>> easier reverting of a Pull Request. We’ll see even
more benefits once 4.7
>>>>>>>>>> is there. Although the intentions to merge the Pull
Request were there, it
>>>>>>>>>> still didn't happen. We should always check before
we push. As a committer
>>>>>>>>>> we just need to be sure.
>>>>>>>>>>> - we need automated testing!
>>>>>>>>>>> The sooner the better. It’s all about the missing
automated testing.
>>>>>>>>>> After 4.6, we all need to focus on this. Saves a
lot of time. And
>>>>>>>>>> frustrations.
>>>>>>>>>>> We're doing final testing on PR #887 and will
merge it soon. From that
>>>>>>>>>> point on we can look into new issues. Be aware that
any PR out there that
>>>>>>>>>> was created after September 10 needs to be rebased
with current master
>>>>>>>>>> (when #887 is merged). Without that, no serious testing
can be done.
>>>>>>>>>>> Let's be careful what to land on master. I'll
only be merging Pull
>>>>>>>>>> Requests that have had proper reviews with information
on what was tested.
>>>>>>>>>> At least one reviewer needs to actually verify it
works (and show the rest
>>>>>>>>>> of us). We simply cannot assume it will work.
>>>>>>>>>>> If we do this, I think we can start resolving
the remaining blockers
>>>>>>>>>> one-by-one and go into the first RC round. Please
help out where you can so
>>>>>>>>>> we can make this a success together. Thanks!
>>>>>>>>>>> Looking forward to the day we have our automated
testing in place ;-)
>>>>>>>>>>> Regards,
>>>>>>>>>>> Remi
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