featured

User authentication with webapp2 on Google App Engine

Google App Engine for Python ships with the capability to manage user accounts without the need of any additional library. This functionality is, however, insufficiently documented. This post will be structured as a step-by-step tutorial addressing user registration, login, password reset and a few other details. The webapp2 framework on Google App Engine for Python 2.7 is definitely a step forward from the original webapp. Despite the increase in flexibility and functionality, however, there are a few items that are still more laborious than in other frameworks. The most notable aspect is user account management. Unsurprisingly, since it is meant to run on Google’s App Engine, using Google Accounts with webapp2 takes one line of code. OpenID authentication, while still defined experimental, is almost trivial to implement as well. There are some open source projects like SimpleAuth that attempt to offer a standard and unified API to handle signing in with Google, OAuth and OpenID accounts. While it generally makes sense to offer support for authentication through popular services – it decreases friction for new users to try a service – in some cases users may prefer having a special login to access your application. As experience teaches us, managing passwords securely is not a trivial task, and users legitimately expect application developers to take all the necessary measures to protect their passwords. Since this is a use case that has to be considered countless time, there is significant value in using library functions to handle user accounts. Here is how to do that using the functionalities embedded in the webapp2_extras package that is distributed with all standard installations of App Engine for Python 2.7.

What you should know before moving to Amsterdam

This post is a bit unusual for this blog: a few months ago I moved from Milan to Amsterdam (curiously, four years after my first visit to the city) and gathered some advice from friends and websites in the process. That information helped a great deal during my first weeks here and ensured that my move was a smooth one. I believe others in the same situation may benefit from the notes I gathered, so I decided to post them here. As an EU citizen with a job offer from a company that has an office in the Netherlands, my transition was quite easy, but there were still some aspects that took me a while to figure out: I will try to cover most of them within this post. For everything else, you may find a lot of useful information in the links at the end of this article.

We need smarter issue trackers

While issue trackers originate as tools to manage projects more effectively, during the last years of work I have been through some situations where their misuse backfired. Tools originally conceived to improve workflows and project lifecycle became a significant burden for the team using them, occasionally making difficult situations even worse. This post is a collection of bad patterns I have seen happening. It is not a survey of all the possible situations that can occur. It is not meant to be an argument against issue trackers (if it tells anything, it will probably be about the teams I was part of), but rather an overview of things that went wrong because of the way a particular team used those systems. In retrospective, most of the problems were due to a lack of discipline and experience of the project teams, and they are less frequent – if present – in a team of seasoned professionals. But, while training and education can certainly help, I would love to consider a different aspect: the issue tracking systems were not helping as they could have. Here is a summary of the most common and annoying problems I encountered The issue tracking system is misused: Lots of issues are duplicates The system imposes over-engineered processes Bug reports do not include enough information The way priorities are managed is broken I would love to build on top of each negative experience, with a constructive attitude, by exploring how a better designed system could induce a better behavior.

Failure is an option

As Software Engineers, we often tend to be overly optimistic about software. In particular, it often happens that we underestimate the probability of systems and components failures and the impact this kind of events can have on our applications. We usually tend to dismiss failure events as random, unlikely and sporadic. And, often, we are proven wrong. Systems do fail indeed. Moreover, when something goes wrong, either it’s barely noticeable, or it leads to extreme consequences. Take the example of the recent AWS outage: everything was caused by a mistake during a routine network change. Right now, some days after the event, post-mortem analyses and survival stories count in the dozens. There is one recurring lesson that can be learned from what happened.