Chris Medrela sped up Travis-CI checks of AMY’s test suite by using
a cache directory
Aditya Narayan as part of his
Summer work added titles and URLs to task
objects in AMY (useful feature for PyData conference integration)
Aditya Narayan changed form for creating new events so that admins can
assign themselves to a new event while creating it
Aditya Narayan added a Sponsorship model to AMY and integrated it with
AMY (we can now track sponsors for events)
Aditya Narayan migrated Host to Organization: it fixed some naming
in v1.6 we dropped support for numerical event IDs to rely only on slugs
(e.g. 2016-08-13-Krakow or 2017-01-xx-Boston), now Aditya Narayan
cleaned some remains left in the code from before dropping the support
I added support for cancelled tag used to mark events supposed to happen
but not happening eventually
Chris Medrela added instructor training workflow, ie. huge part of AMY
used for instructor training
Aditya Narayan added a feature for importing people, events, tasks from
PyData conference site in a comfortable way
Chris Medrela tracked and fixed an error in part of AMY responsible for
allowing users to log in with other credentials than user/password
(currently: GitHub login)
I fixed an API error occuring in some views (endpoints) when using CSV or
YAML return format
Whoa, another one?! Yesterday we released v1.6.1, today it’s time for
v1.6.2 with some very minor changes.
New fields in the training request form:
group name will enable us to register groups for the training, without
(for now) the need for a new form
comment will be a place for any additional information; instead of it,
people would use additional skills.
Event.slug received new help text containing a format description for
admins to use. This field’s validation was also changed so that it only
allows entries in this specific format (this is additional to other
validation done by Django, ie. only latin characters, digits, underscores and
Migration 0088*, which was supposed to generate fake slugs for events
without them, contained an error that we hit in the production, so I fixed it
by adding random characters to the slugs if uniqueness constraint was about
to be violated.
We’re taking momentum! Two days after v1.6 release, we’re releasing a minor
bug-fix version v1.6.1 which is not as small as you might think.
Aditya Narayan changed the default value for invoice status field for
events to “Not invoiced” (it was: “unknown”).
I added a link to the login form on the logout page. In future, we’re going
to redirect to the login page with a message,
but we’re waiting for Django to release a feature that will allow us to do
I restyled login page so that it’s clearer that people can use user+password
OR GitHub account to log into AMY.
Chris Medrela provided tests that make sure we don’t have bugs associated
with saving M2M-related objects in an AutoProfileUpdateForm.
I added a link to the profile view page in the top navigation bar. This
links to a trainee-dashboard page if current user is not an admin, and to
a person-details page otherwise.
Chris Medrela fixed indentation of lists when they’re placed inside of
Chris Medrela fixed wording in one field of the aforementioned form.
I added a missing migration (we commonly forget to add migrations when
there are small changes introduced).
Aditya Narayan changed some text fields in AMY’s models so that they
cannot be equal to a NULL (or None) value. Instead an empty string is
used for these fields’ default values. Some fields, especially ones with
a uniqueness constraint, had to be left as nullable. In particular, this
makes the Event.slug a required field.
Aditya Narayan continued W. Trevor King’s work on the Language
model and now we can accurately track languages amongst multiple forms and
related models (e.g. events and persons).
Aditya Narayan added a summary of tasks per role on person’s details
Chris Medrela added an application form for individuals wanting to become
I added Language support in additional forms (original PR was missing
language support in some forms).
Big: Chris Medrela worked hard to bring GitHub authentication into
AMY (with success!). There are some caveats, but we’ll smoothen them out for
the next release. This work included opening AMY to other users (a move we
were afraid of), and tests for each and every test to ensure we got the
In the same PR, Chris Medrela added an AutoUpdateProfileForm used by
users (who can log in from GitHub) to self-populate their profiles.
I fixed a bug that caused IntegrityError when people with similar tasks
(task has a role, person, and an event; tasks for these people were the
same except person was different) were being merged. IntegrityError
means that a uniqueness constraint was violated (ie. after the merge there
were two Task(role, personA, event), which is prohibited).
Chris Medrela fixed interpolation on some of our charts that looked like
the data was swinging, while in reality it wasn’t.
Aditya Narayan fixed default field values on the
“All activities over time” page; now the fields have meaningful default
values and the datetime inputs have a proper calendar widget.
Aditya Narayan reworked teaching frequency report to eliminate bug that
duplicated numbers for people simultaneously marked as SWC and DC
I fixed some corner cases in event validation (behavior for required or
optional tags/metadata (see below)).
I fixed a bug resulting in 500 Server error when accessing weblink to
a non-existing Host.
Chris Medrela added one small migrations missing from the codebase.
Greg Wilson fixed a bug in API that prevented list from working on the
generator objects for some renderers (CSV and Yaml).
Prerit Garg fixed a specific bug preventing saving a permissions form
when person’s email field is empty.
Chris Medrela fixed a TrainingRequest form that display additional
fields (that weren’t supposed to appear).
Chris Medrela refactored “tags” to “metadata”; tags as key-value pairs
describing workshops’ date, times, location, instructors and helpers. We
changed the naming to “metadata” to not confuse with Tag model.
Chris Medrela sped up our tests by changing hashing algorithm to a slower
one, which – surprisingly – is one of suggested test speedup suggestions by
Django development team.
I’d like to thank Greg Wilson for supporting us throughout the exams, and
even when we disappointed him by continuously not delivering and rescheduling
this release. Greg, you’re awesome!
Finally I also want to point to Chris Medrela’s
blog where he regularly posts AMY’s
development during this Summer of Code.
Yesterday AMY v1.5.4 was released with a bunch of interesting changes.
AMY is now capable of going through all active workshops and checking if
their metadata (slug, start/end date, instructors and helpers) had changed.
If so, a notification would be shown to the person associated with the event.
Aditya Narayan improved history log by enabling it to show related
objects’ real names instead of IDs.
Greg Wilson added a button to mail everyone involved in a workshop
as part of his GSoC 2016 project, Chris Medrela added the trainings
dashboard in its first shape
Chris Medrela in collab with Greg Wilson added SWC/DC instructor
badge indicators to: all persons, event details, and “find instructors” views
Finally, I upgraded the “Find instructors” view to enable admins to search
for not only instructors, but also in-progress instructor trainees and people
who once had been associated with the workshop organization. Therefore the
new name for “Finding instructors” is now “Find Workshop Staff”.
Aditya Narayan fixed permissions issue when accessing event details page
by people without permission to add ToDo items.
I fixed a small error preventing DataCarpentry logo from showing up on DC
workshop request page.
I fixed a small error doubling people with both superuser and admin group
permissions in the admin lookup backend.
Even smaller error was pointing admins to use wrong URL in import event
template. It is now fixed.
Chris Medrela fixed the former “debriefing” view (now
“instructors by date”) errors concerning emails generation when some people’s
emails were unavailable.
Chris Medrela fixed I think the oldest unnoticed issue ever: wrong link
generated for airport’s IATA code.
Finally, Chris Medrela fixed missing template from one of the new
features for this release.
I’d like to thank Chris and Aditya for their continuous work on AMY. This is
just the beginning, and if you’re curious go check out what’s planned for
v1.6 (probably the next release). There’s a lot happening around AMY
recently, so stay tuned for the next release.
This observation led to an investigation on the servers and eventually to fix
for a critical bug that caused the data loss.
But before we jump into sysadmin work…
What is a “tag” in AMY terms?
A tag is label that we give to various workshops. For example, all Software
Carpentry workshops will have SWC tag, and all Data Carpentry workshops will
have DC tag.
There are more labels we use, and the one that went missing was DC.
One event can have between zero and all the tags we have in the system, which
means it’s a many-to-many relationship between events and tags. This type of
relationship requires additional intermediate table in the database.
Contents from that table were missing because they were removed with removal
of the DC tag.
I started the investigation by narrowing timespan where the event, that led to
data loss, occurred.
Then I followed by reading WWW server access logs to find out what happened in
that timespan in hope I could find the bug.
After narrowing list of suspects, I was able to reproduce the bug.
Finally I retrieved the lost data from the most recent backup that still had
Ways to remove tags from AMY
There’s no interface for removing tags other than Django’s auto-generated admin
interface; only a couple of people have access to it.
So the data loss was either human error or it was caused by code bug. This
conclusion helped me define what I should be looking for in the WWW server log.
Narrowing event occurence timespan
AMY’s being backed-up by multiple systems; I logged into each of them and run
multiple SQL queries on different databases to find out which backup had the
DC tag and was the newest.
It turned out that backup from 2016-04-06 17:00 UTC-4 was the most recent still
with the DC tag.
In the meantime I was fighting timezone correction… Our backup systems are in
different datacenters and were running on different timezones.
Reading access log
First thing I checked in the access log is if anyone was using the admin panel
to remove the tag. Unfortunately this possibility was quickly ruled out; so
the loss was caused by code bug.
However, after reading the log no action stood out.
Short, important side story: Software Carpentry website rebuilds every 30
minutes. Each rebuild is shown in the log by multiple requests to AMY’s API:
Website grabs published events tagged by SWC, DC and TTT tags. This
sequence of requests repeats every 30 minutes.
After reading the log over and over I noticed that two consecutive calls to
/api/v1/events/published.yaml?tag=DC yielded results of very different
Apparently then the DC tag disappeared, the API started returning all the
published events, no matter if they were tagged SWC or something else.
This was a clear indication that the DC tag disappeared between 15:01 and
That timespan doesn’t look like 17:00. Timezones… programmer’s nightmare.
There was some user activity in this 30-minutes long window and one thing
caught my eye:
(The actual URL was slightly changed to remove unnecessary information.)
This was a call to event merge functionality: someone wanted to merge
workshops 2016-05-06-RDAP16-Atlanta and 2016-05-06-asist.
Short side note: merge functionality allows user to use more advanced
strategy for merge; one can select which properties (or fields) in the final
event should be used from event A (2016-05-06-RDAP16-Atlanta in our example)
and which should be from event B (2016-05-06-asist). Additionally in case of
event’s tags it’s possible to combine them from both base events.
I started testing different strategies. I had a feeling that the bug had
something to do with strategy for event tags. :)
Finally I reproduced the bug by using following strategy:
base event: 2016-05-06-RDAP16-Atlanta (event A)
tags: from event B.
At that point I decided to retrieve the lost data using SQL import/export
functionality from the optimal (newest & containing the lost data) backup found
The only code used in event merge functionality that would trigger accidental
This code is used for substituting related objects (tags in our case). It works
if some field’s strategy is to switch to objects from the other event, then
remove all currently assigned objects and add objects from the other event’s
Translated into tags:
if user wants to use event 2016-05-06-RDAP16-Atlanta as base event, but
keep tags from the other event (2016-05-06-asist) then remove current tags
from base event and add tags from the other event.
See what’s going on here? Base event’s tags were removed instead of being
Django: related manager and assignments
In this section I’m going to talk about how relations work and if they can be
unassigned instead of being removed.
For many-to-many relationships (e.g. multiple events can be assigned multiple
tags) Django creates an intermediate table that stores assignments. In this
case, unassigning event from tag is as simple as removing that stored
assignment from the intermediate table.
For one-to-many relationships (e.g. multiple events can have the same
organizer) there’s no need for additional table; storing the organizer looks
like event.organizer = SomeOrganizer.
In case of the one-to-many relationships we can unassign the event from
SomeOrganizer if and only if event.organizer field can store NULL value.
If it cannot, then we have to remove the event.
So the bug existed because the case of unassignment was not taken into account
– only removal of related objects was accounted for.
Fix: need to find out when we can unassign
Long story short: in Django only related manager with .clear method can
unassign; if this method is not present then the only option is removal.
So fixed code looks like this (minus the comments):
(Yes, it probably should use try - except block instead of hasattr; pull
All in all, I feel good about this bug; if anything, I’d like eliminate the
errorneous timezone arithmetics.
Also all backup mechanics and logging worked really nice.
As a result of investigation described above, the bug and the solution to it
last night I released AMY v1.5.2.
Since my comeback to university for MSc, the development of AMY slowed down.
This past month we had a number of submissions from prospect GSOC’16 students
(yay!) and, for the first time, number of bugs fixed exceeded number of new
Since the number of new features is small, I decided to release a minor version
Contributions by GSOC students
March 2016 held GSOC’16 applications period for students. We had a lot of
students this year and we encouraged them to take a look at AMY and maybe fix
something. This resulted in a number of good contributions.
Starting with new features since there’s so few of them:
Greg Wilson extended the check_certificates.py command to additionally
return events people participated in
Shubham Singh added “Notes” field to instructor profile update form
Development of AMY in February had seen a boost due to my winter break
(I graduated university and had about a month of free time before MSc studies
started), and that ended with today’s release of v1.5.