Oct 102019

(Or, as it's commonly known, yak shaving.)

In this case, to be able to use a Docker image, the easy way to install software (I'm told). But, of course, technology has a habit of throwing curve balls. Or, as here, demanding items that you may not have.

Step One: Checking the requirements for Docker reveals that, if you're using Windows, you need a Windows 10 Pro installation, not Windows 10 Home. There is, however, a Docker Toolbox option for Windows 10 Home. The requirement for Docker Toolbox includes virtualization being enabled. (There's a link to a tool to check this.) My Windows PC, a couple of years old, has that virtualization, but it's disabled.

The wording on the Docker Toolbox page makes it sound like using the full Docker Desktop would be preferable, so I decided to check out that option. Microsoft does make it easy to spend the money to upgrade to Windows 10 Pro (there's a link in the Settings app under About with the word "Upgrade"), but the requirements for Docker Desktop include support for something called "Second Level Address Translation (SLAT)", which seems to be called something different anywhere you might want to check it. In the Windows system information (systeminfo) it's called Hyper-V, for example, and checking it reveals that in my system it's supported, but not enabled.

Step two: Enable virtualization; this requires a reboot and change to the system BIOS settings. This page on how to access the BIOS on Windows 10 was useful. Once enabled, everything seems good to go, and from there I decided to try out the toolbox first, and think about the larger upgrade later. I'm not crazy about potentially breaking working systems if I can avoid it, and past Windows upgrades have made me cautious.

Step three: Install Docker Toolbox, which went smoothly enough. But the program I was trying to run had issues with port mapping. A possible cause is something in the Docker system not talking to the Windows system in the expected way, so it looks like I will need the full Docker Desktop after all. Which means upgrading Windows.

Step four: Delete Docker Toolbox from the system to make sure there are no weird interactions.

Step five: Sign up for a Microsoft account, so that I can buy Windows 10 Pro.

Step six: Install Windows 10 Pro as an upgrade to Windows 10 Home. This went much faster than I expected and apparently didn't break anything either.

Step seven: Install Docker Desktop and repeat all the software-dependent installation steps.

Success! The port mapping works, and the required software installed.

Technology is great, except when it isn't. But Windows 10 is much better than previous versions of Windows.

Feb 042018

Posted in case it helps someone else.

One of my website clients asked for help with one of their Mac OS X laptops, which had suddenly stopped connecting to their wifi network. The wifi connection seemed to be demanding a WPA enterprise username and password, despite being set up as WPA2 personal, which only needs a password.

In the end, the cause was a combination of a new modem/router from the cable company, and an old version of Mac OS X (10.7.5). I had to go to the app store to download El Capitan, since you can’t update from 10.7.5 to High Sierra directly, but after installing it the laptop could connect to the WPA2 personal wifi network on the new modem/router. It’s now been updated to High Sierra, and the company reminded to install the updates they get a little more regularly…

Jul 232017

For a while there XML.com didn’t handle tags on submitted news items very well. If a tag was included that was in a different case to an existing tag, the preview and publish would result in a 500 server error. Fortunately this was something that wasn’t visible to the outside world, but annoying nonetheless.

Wagtail allows case-insensitive tags, and I had already turned that on (it would be confusing to have searches for the tags “XSLT” and “xslt” return different results, for example). Articles and news items submitted using the standard interface behaved properly, it was just the news items submitted by people without logins on the system that didn’t.

It turns out that the problem lay in the way I called the get_or_create() method, which is used to look up the tags in the database and then create them if they don’t exist. In my code, that looked like this:

tag, create = Tag.objects.get_or_create(name=tag_name)

By default, this is a case-sensitive method (as it should be, for the general case). To make the lookup case-insensitive, you use name__iexact instead of name. The next problem I found was that no tags were being created if the tag didn’t already exist in the database. To create the tag, if you’re using name__iexact instead of name for the tag lookup, you also need to give the get_or_create() method a defaults parameter to use when creating the tag. Now that line looks like this:

tag, create = Tag.objects.get_or_create(defaults={'name': tag_name},

and it all works the way it’s meant to.

Apr 082017

If you have MathML on your WordPress site, using the Mathjax system to show it, then you need to know that Mathjax is shutting down the CDN as of April 30, 2017. If, like me, you use the MathJax-LaTeX plugin, the solution is easy.

Go to the Plugins – Settings – MathJax-LaTeX page. Uncheck the “Use MathJax CDN Service?” checkbox, and add https://cdnjs.cloudflare.com/ajax/libs/mathjax/2.7.0/MathJax.js to the “Custom MathJax location?” text field. You can, of course, also download the MathJax scripts and install locally, but I prefer to use a CDN.

Save the changes, and you’re all set! Unfortunately there isn’t an equivalent of the MathJax ‘latest’ for the scripts, so every now and then you’ll need to update the location, but other than that there should be no differences.

Mar 262017

Let’s Encrypt has made it much easier for web sites to use https instead of http, even those on shared hosting. In my case, all I needed to do was ask my ISP, Canadian Web Hosting, to move my accounts to a server that supports a cPanel extension (I assume this one). Installing the certs is trivial.

Changing the basic WordPress setting was easy – update the WordPress Address (URL) and Site Address (URL) settings in General. This did break a lot of image links, mostly because I’ve had my blog on WordPress for so long that I still had all my images in a custom image directory and the gallery couldn’t find them any more. That took a certain amount of fiddling, and I haven’t yet got all the images in the old posts back to the way they were.

Another thing that broke was my spam detection. I used Spam Karma for many years, and even after it was no longer updated it was suitable for my needs. But it doesn’t work with https for some reason. I’ve now switched to Antispam Bee and find it does what I need. I haven’t noticed any spam slipping through, nor real comments being marked as spam. Most of the competitors had some feature I didn’t like, such as by default deleting comments without my having a chance to check them. That would be useful on sites with lots of spam, but not necessary for mine. It has a well-deserved high rating on the WordPress plugin site.

Overall, switching my sites to https cost me a couple of hours work and the time waiting for the new server DNS to propagate. Well worth it.

Feb 012017

I coded XML.com in Wagtail, a CMS based on Django. It works well for my needs and I like Python as a programming language. One of the big reasons I like Wagtail is that it includes a powerful enough but not overly complicated workflow with roles and a built-in moderation and preview system.

But, I wanted a system where people could submit news items that would go into the moderation queue without needing to sign up for a login first. Fortunately, Wagtail makes that possible, and there’s a nice article by Erin Mullaney at Wagtail: 2 Steps for Adding Pages Outside of the CMS that details all the steps you need. It all worked nicely in more recent versions of Wagtail (thanks, Erin!) except for one part, the notification that the news item is in the moderation queue. That wasn’t a stop-ship item, so XML.com launched without those emails working.

I’ve now found the source of the problem. It turns out that when you submit a news item in this way, it doesn’t have a login identity attached to it (obviously, since there isn’t one). The send_notification function that sends the email uses templates, and these templates use the login identity of the author in the body of the email. Since that doesn’t exist, the whole function fails.

That means the solution is easy. The affected templates are wagtailadmin/notifications/submitted.txt and wagtailadmin/notifications/submitted.html, and Wagtail lets you customize the admin templates. I put my customized admin templates into a utils application, which contains all my utilities for the site. My utils/templates/wagtailadmin/notifications/submitted.txt file now has the content

{% extends 'wagtailadmin/notifications/submitted.txt' %}
{% load i18n %}

{% block content %}
{% blocktrans with page=revision.page|safe %}The page "{{ page }}" has been submitted for moderation.{% endblocktrans %}

{% trans "You can preview the page here:" %} {{ settings.BASE_URL }}{% url 'wagtailadmin_pages:preview_for_moderation' revision.id %}
{% trans "You can edit the page here:" %} {{ settings.BASE_URL }}{% url 'wagtailadmin_pages:edit' revision.page.id %}
{% endblock %}

Similar changes are necessary for the wagtailadmin/notifications/submitted.html file if you want to send HTML emails instead.

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