26 November 2018

How to get Google Home / Google Assistant to call your iOS iPhone

If you have an iPhone, Google Assistant and Google Home won't be able to call or ring your phone out of the box, since it's an Android-only feature. If you are not in the US, you cannot even use the workaround of calling your number. So what can you do, if you tend to misplace your phone around the house ? (ahem)
  1. Get an account on IFTTT
  2. Install the IFTTT app on your phone
  3. create a new applet, click on "this" and select Google Assistant
  4. select "say a simple phrase"  and enter the details you prefer (e.g. "make a noise on my phone" or "ping my phone". Note the most common "ring my phone" or "where is my phone" are reserved by Google and won't work).
  5. click on "then" and select VoIP Calls
  6. enter a message the phone will tell you if you pick up (e.g. "Glad you found me!")
  7. Save the applet.
Now, when you say that phrase to Google Home / Goole Assistant, it will ring your phone, so you can dig it out of the sofa or the Lego box (ahem).

15 August 2018

how to load initial data and test data in Django 2+

There are two ways to automatically load data in Django:

  • for data you need while running tests, place xml/json/yaml files in yourapp/fixtures.
  • for data you need while setting up the database from scratch, or at specific points in time, you must create a Migration

This is a bit annoying, because chances are these locations will get out of sync sooner or later, and it duplicates effort if you do reproducible builds, docker, and stuff like that.

The solution is to create a migration that actually loads fixtures. So:

  1. Create your fixtures: manage.py dumpdata --output yourapp/fixtures/yourmodel.json yourapp.YourModel
  2. Create an empty Migration: manage.py makemigrations --empty yourapp
  3. Edit the resulting migration (the last file created under yourapp/migrations, making it look like this:
    from django.db import migrations
    def load_fixtures(apps, schema_editor):
        # This is what will be executed by the migration
        from django.core.management import call_command
        # this is the equivalent of running manage.py loaddata yourmodel.json
        for fixture_name in ['yourmodel']: # add any additional model here
            call_command("loaddata", fixture_name)
        # add other calls if you have multiple models
    def rollback(apps, schema_editor):
        # This will be executed if you rollback the migration, so you want to clean up
        for model_name in ["YourModel"]:  # add any additional model here
            model = apps.get_model("yourapp", model_name)
    class Migration(migrations.Migration):
        dependencies = [
          # ... don't touch anything here ...
        operations = [
            migrations.RunPython(load_fixtures, rollback),
    # -*- coding: utf-8 -*-
  4. Profit

Note that this does not remove the option to have data that is available only in certain situation: just don't list the fixtures you don't want in the migration, and vice-versa.

24 May 2018

How to securely wipe an NVMe drive

NVMe drives are great: they are fast and they are huge. That huge size, however, can be a pain when it comes to securely erasing data. Old-school commands like wipe are simply not up to the task; and even if they were, they work on assumptions that do not map properly to a solid-state world. Writing random data over and over is going to dramatically reduce the lifespan of a solid-state drive, and it's pointless when all NVMe disks already have built-in tools that can take care of this task quickly and safely.

So what do you do when you want to wipe a NVMe drive?
  1. Download a recent Linux distribution. I would recommend Debian/Ubuntu or one of their smaller derivatives (like Knoppix). Burn it on a cdrom or USB drive and boot the system from it.
  2. Make sure your package manager is up-to-date (under Debian/Ubuntu, sudo apt-get update), then install nvme-cli (sudo apt-get install nvme-cli)
  3. If your drive is a Samsung, it now has to be put to sleep (you can do that with sudo systemctl suspend) and then woken up. This is a weird bug that Samsung doesn't seem in any hurry to fix.
  4. Now you can securely wipe the disk: sudo nvme format -s1 /dev/nvme0n1
For the curious: the -s option triggers Secure Erase mode, which can be set to 1 (wipe) or 2 (delete encryption keys for encrypted data). 1 looks like the safest option, because it will automatically do what 2 does if it detects that all data is encrypted. Reference here.

The latest NVMe specification adds other commands, to scrub every nook and cranny (bus caches etc), but as far as I know they have not been implemented yet.

15 May 2018

New Beginnings

So, after 7 intense years at Infratects (now Inlumi), it's time for me to move on.

I have a few ideas about what to do next, but nothing set in stone yet. My LinkedIn profile could do with more details, but it's a decent primer for what I do for a living - Hyperion/EPM, Python, Java, Weblogic and thereabout.

I was a web developer in a previous life, so I enjoy hacking and automating everything, getting dirty with infrastructure and the cloud; and in 13 years working on Hyperion products, I've absorbed a pretty good amount of knowledge related to financial processes (consolidation rules, metadata, cube performance and so on) as well as a deep understanding of the innards of the EPM suite. I can tweak your database, hack your Weblogic, integrate your cloud-based authentication, script your exports and migrations, and so on; and if there is something the tools won't do... I'll build you a new tool! That's where I make the difference: at the intersection of technology and Finance, boosting the productivity of accountants.

If this sounds interesting, ping me on LinkedIn and we can have a chat.

16 April 2018

Nespresso Blends - a comprehensive spreadsheet

As a faithful Nespresso user, I was a bit shocked last month when I discovered one of my favourite blends contained Robusta. I had always assumed all blends were 100% Arabica and alas, that was not the case. So I started looking up what is what, but I was quickly overwhelmed - I wasn't going to browse through 24 pages of slow-loading images to read all blurbs. Enter Python.

As it often happens, the situation degenerated quickly. The result is an Excel spreadsheet (also available in Google Docs), listing all attributes of all blends so that you can filter out what you need. Decaffeinated varieties are highlighted, because that's not real coffee ๐Ÿ˜

28 March 2018

How to implement custom BotStorage class for Microsoft BotFramework

Since launch, the MS BotFramework has been changing very rapidly. So rapidly, in fact, that I recently gave up trying to keep up with my handrolled Python, and embraced (sigh) their NodeJS SDK. At least now I won't have to worry when they break stuff, right ?
One of the most recent BF changes is the deprecation and eventual removal of the default persistence API. You are now supposed to either use one of the pre-built Azure services (paying $$), or provide your own implementation. In pure Microsoft style, they state that rolling your own is very easy... but never actually provide a sample or even tell you which interface should be implemented.
I had to scavenge through their code to figure it out (at least they opensource their stuff these days), but I thought I'd save others a bit of aggravation, and here it is:
var MyBotStorage = (function () {
    // optional constructor
    function MyBotStorage(options) {
        this.options = options;
    MyBotStorage.prototype.getData = function (iBotStorageContext, 
        // IBotStorageData interface
        var data = {
            userData: {},
            conversationData: {},
            privateConversationData: {}
        // the callback MUST be invoked
        // signature: callback(Error, iBotStorageData )
        callback(null, data);
    MyBotStorage.prototype.saveData = function (iBotStorageContext, 
        // the callback MUST be invoked
    return MyBotStorage;

var botStorage = new MyBotStorage({});

var bot = new builder.UniversalBot(connector, function (session) {
            // your bot code here
    }).set('storage', botStorage); 
As you can see, it is indeed trivial, once you know how. It's sad that MS somehow, in the haste of deprecating their older interfaces, couldn't find the time to put this sample in their otherwise-extensive documentation. I suspect the fact that Azure is not mentioned anywhere might have something to do with it, but I'm sure I'm just assuming excessive malice and there is a perfectly-plausible explanation that does not involve greed. Or is there?

26 March 2018

Appstores need a Trial Mode

I've been looking for a while for a Windows-native Twitter client that could sync with my other non-Windows devices (aka "supporting TweetMarker"). I've found one that claims to do that, Tweet It!, but there is a problem: it costs £3.5 upfront. That's a relatively high amount of money to throw down a well hoping that my wish will come true. However, because this feature is so rare, if it worked I'd be happy to pay three times as much, no questions asked. I just have no way to find out.

Appstores need a simple Trial Mode. All the current hacks (In-App-Purchases, subscriptions, refunds etc) are just that, clumsy workarounds to this glaring omission, which is why app prices are so squeezed down - to the chagrin of indie developers. Trial Mode would also bring huge collateral benefits like reducing reliance on SaaS services (something that Microsoft in particular should relish) and creating viable alternatives to the free-to-play bubble that has turned online gaming into a socially-accepted form of gambling addiction.

I doubt Apple will ever introduce Trial Mode - they are the dominant player and have little incentive to change the rules; and Android is a far west where the Play Store is almost irrelevant. But Microsoft should experiment with something like this, while the Windows Store is still young and evolving. Both developers and users would love it, they have been asking for something like this for years.

04 March 2018

The European Union, explained to geeks

I've started describing the EU to geek-friends as a set of services built over decades.
  • You need to coordinate energy supplies across the company departments (nations)? We built a service (ECSC) that does that. Worked great, no more fighting over the last bit of coal!
  • Need atomic development? EURATOM service. Worked great, again.
  • And so on and so forth...
  • At some point somebody said hey, we need a management tool for all this stuff! "European Council" service, with a set of dedicated subthreads for the real work (European Commission).
  • But that service will run amok at times, let's add some monitoring and security checks! EuroParliament service - took a few rewrites to get right, nobody really likes to work on monitoring tools; but like systemd on Linux, the EP service should eventually take over anything that talks to real world I/O, so it's pretty important.
  • Now all this stuff needs to communicate, with common formats that avoid parsing and reparsing umpteen different types of data back and forth, and ways to look up the right service for a given job - so we created a "CommonMarket SDK", optionally turbocharged with options like Schengen. When exceptions are thrown, the SDK will automatically invoke the ECJ service to resolve matters; and it will self-update by talking to the management services. Once everyone adopts the SDK, then it should be easier to make more radical changes through that (ECB, Euro, common fiscal policy...). But in the end nobody likes change, it's always hard to break backward-compatibility.
Now, across the company/continent, various departments/nations have adopted some or all of these services, but most of them ended up relying on the SDK one way or the other, so it became basically mandatory. At one point we had to give a name to the whole framework, and "EU" it was.
It's definitely not a monolith, but there are so many moving parts that the management services are now essential. Some departments have renounced their Write access (Iceland, Norway, Switzerland...) and some were never granted that privilege (Turkey); some departments were forced to change their processes to suit the framework (Italy, Greece, the Eastern countries...). Things are still pretty shaky, developers are still very much at work, but it's getting better with time. It's making more and more services possible and even *easy* to bootstrap (EMA, EFSA, Erasmus...). Bugs creep in and out, we keep adding more and more fault-tolerance, the workload is not yet distributed fairly, etc etc; but it's accomplishing some very heavy tasks that are absolutely mission-critical, if we want to keep the company running and competing with the big boys.
Then, one day, a department said they'd like to go back to pen and paper. Except for a few services, for which they want to hand-craft packets individually, but those services should just assume the data is still as good as before, and never throw exceptions - they will ignore any response from the ECJ service anyway. Some of what their department does depends on another department, which has no intention to go back to pen and paper, but they say they will somehow give them bits and receive paper, without anyone actually doing the transformation, and without any friction at all. And they'd like to retain write access to the management services too, thank you very much, plus veto powers, so nobody can change SDK formats without consulting them.
Cue facepalming.

25 January 2018

Windows Survival Kit for OSX exiles

After 5 long years, I was gently forced back to Windows for everyday work. The experience has been less terrible than I thought, but was pretty frustrating at the beginning.
To help anyone in the same predicament, I put together a small list of tips to make the move a bit more tolerable.
  • Windows does not have hot corners. Hello, 1995! Anyway, the solution here is using a small app called, unsurprisingly, HotCornersApp. It works well enough, and it's fine with multiple screens too. Despite the basic website, it's legit and even opensource, you can compile it yourself (although beware - apparently the very latest updates may not build properly).
  • Windows does not do text substitution, which is one of those things that you don't know how much you love it until they take it away from you. As far as I can see, there is no free utility on Windows to do this, or nothing that actually works well enough. So, I paid for Breevy. It feels a bit retro (it looks blurry on high-def screens...), but it works very well and has all sorts of options and special features.
  • Windows doesn't really deal well with multi-language support, aka typing accents from a US keyboard. Sure, you can use US-International, and deal with ' and " becoming meta-keys, but for a techie/programmer typing those characters on their own more often than accents, it's extremely annoying. The solution was again Breevy: you can define a combo that will not be triggered unless you type a special character afterwards. For example, I defined `e to become รจ after I press Ctrl. It works absolutely everywhere, although it's nowhere as elegant as the OSX popup. Same story for special characters like £ , € etc.
    • For best results, check if your keyboard supports custom macro. Mine does, so I mapped the blank side-keys to accents and so on. After muscle-memory starts kicking in, this solution is actually superior to stock OSX.
  • I was not going to reformat my external hard drives to NTFS, which is a pain to use back on OSX; so again I had to pay for Paragon HFS+ for Windows. The UI is garbage (and does not work properly with multi-monitor setups), but the actual driver seems to work perfectly.
  • Microsoft has basic print-to-PDF support. If you need to concatenate documents, PrimoPDF does it, and it's free (do not download the Nitro version). The interface is not great though.
  • For the developer types out there who rely on Dash, a good equivalent on Windows is Zeal. It supports the same format, even fetching docsets directly from Dash repositories.
  • Also for developer/sysadmin types, the Windows equivalent of homebrew is now Chocolatey. Whoever came up with that word should give up trying to name things, but the software does work. You can use it to install 7zip (to get the latest beta with proper security patches, choco install 7zip.install --pre -y) windirstat and so on, it will make it easy to upgrade them when necessary (rather than having through the usual website-download-install dance, just choco upgrade them all).
  • There are quite a few apps that do what Fluid does, i.e. making websites into "native" apps. I know, I know, they are aberrations; but I got used to having a few sites (Gmail, Trello, Hangouts...) accessible this way. After a bad experience with WebCatalog (it was working ok, but then it got stuck trying to upgrade itself), I installed nativefier. This is again more for the geek types; it requires npm and it's a command-line app with a few quirks.
  • UPDATE 1: to get back the "preview on pressing Space" experience, there is a free app called Seer. You can also pay for a license, but it's not clear what the difference might be, the free app is more than enough for my needs. I had to remove the Ctrl-Alt-S shortcut in Settings in order to make it work properly.
Did I miss anything? Feel free to suggest other useful tidbits in comments.