If you’re working with mozilla-central on Windows and followed the official documentation, there’s a good chance the MozillaBuild shell is running in the default cmd.exe console. If you’ve spent any amount of time in this console you’ve also likely noticed it leaves a bit to be desired. Standard terminal features such as tabs, splits and themes are missing. More importantly, it doesn’t render unicode characters (at least out of the box).

Luckily Microsoft has developed a modern terminal that can replace cmd.exe, and getting it set up with MozillaBuild shell is simple.

This post was co-authored with Marco Castelluccio, and was originally posted to the Mozilla Hacks Blog.

A browser is an incredibly complex piece of software. With such enormous complexity, the only way to maintain a rapid pace of development is through an extensive CI system that can give developers confidence that their changes won’t introduce bugs. Given the scale of our CI, we’re always looking for ways to reduce load while maintaining a high standard of product quality. We wondered if we could use machine learning to reach a higher degree of efficiency.

Mozilla recently announced that we are planning to de-commission irc.mozilla.org in favour of a yet to be determined solution. As a long time user and supporter of IRC, this decision causes me some melancholy, but I 100% believe that it is the right call. Moreover, having had an inside glimpse at the process to replace it, I’m supremely confident whatever is chosen will be the best option for Mozilla’s needs.

I’m not here to explain why deprecating IRC is a good idea. Other people have already done so much more eloquently than I ever could have. I’m also not here to push for a specific replacement. Arguing over chat applications is like arguing over editors or version control. Yes, there are real and important differences from one application to the next, but if there’s one thing we’re spoiled for in 2019 it’s chat applications. Besides, so much time has been spent thinking about the requirements, there’s little anyone could say on the matter that hasn’t already been considered for hours.

This post is about an unrelated, but adjacent issue. An issue that began when mozilla.slack.com first came online, an issue that will likely persist long after irc.mozilla.org rides off into the sunset. An issue I don’t think is brought up enough, and which I’m hoping to start some discussion on now that communication is on everyone’s mind. I’m talking about using two communication platforms at once. For now Slack and IRC, soon to be Slack and something else.

Different platform, same problem.

Mozilla uses a lot of Python. Most of our build system, CI configuration, test harnesses, command line tooling and countless other scripts, tools or Github projects are all handled by Python. In mozilla-central there are over 3500 Python files (excluding third party files), comprising roughly 230k lines of code. Additionally there are 462 repositories labelled with Python in the Mozilla org on Github (though many of these are not active). That’s a lot of Python, and most of it is Python 2.

With Python 2’s exaugural year well underway, it is a good time to take stock of the situation and ask some questions. How far along has Mozilla come in the Python 3 migration? Which large work items lie on the critical path? And do we have a plan to get to a good state in time for Python 2’s EOL on January 1st, 2020?

I’ve recently redone my website and wanted to document a few of the changes and motivations behind them.

It’s no secret that I’m not a fan of try syntax, it’s a topic I’ve blogged about on several occasions before. Today, I’m pleased to announce that there’s a real alternative now landed on mozilla-central. It works on all platforms with mercurial and git. For those who just like to dive in:

$ mach mercurial-setup --update  # only if using hg
$ mach try fuzzy

This will prompt you to install fzf. After bootstrapping is finished, you’ll enter an interface populated with a list of all possible taskcluster tasks. Start typing and the list will be filtered down using a fuzzy matching algorithm. I won’t go into details on how to use this tool in this blog post, for that see:

$ mach try fuzzy --help  # or
$ man fzf

Imagine this scenario. You’ve pushed a large series of commits to your favourite review tool (because you are a believer in the glory of microcommits). The reviewer however has found several problems, and worse, they are spread across all of the commits in your series. How do you fix all the issues with minimal fuss while preserving the commit order?

I’ve previously blogged about why I believe try syntax is an antiquated development process that should be replaced with something more modern and flexible. What follows is a series of ideas that I’m trying to convert into a concrete plan of action to bring this about. This is not an Intent to Implement or anything like that, but my hope is that this outline is detailed enough that it could be used as a solid starting point by someone with enough time and motivation to work on it.

One of the most painful aspects of a developer’s work cycle is trying to fix failures that show up on try, but which can’t be reproduced locally. When this happens, there were really only two options (neither of them nice):

1. You could spam try with print debugging. But this isn’t very powerful, and takes forever to get feedback.
2. You could request a loaner from releng. But this is a heavy handed process, and once you have the loaner it is very hard to get tests up and running.

I’m pleased to announce there is now a third option, which is easy, powerful and 100% self-serve. Rather than trying to explain it in words, here is a ~5 minute demo:

Mach is the Mozilla developer’s swiss army knife. It gathers all the important commands you’ll ever need to run, and puts them in one convenient place. Instead of hunting down documentation, or asking for help on irc, often a simple |mach help| is all that’s needed to get you started. Mach is great. But lately, mach is becoming more like the Mozilla developer’s toolbox. It still has everything you need but it weighs a ton, and it takes a good deal of rummaging around to find anything.

Frankly, a good deal of the mach commands that exist now are either poorly written, confusing to use, or even have no business being mach commands in the first place. Why is this important? What’s wrong with having a toolbox?