Monthly Archives: January 2025

Basic use of the Elixir interactive shell

If you’re wanting to play around with Elixir in a REPL you can use iex.

Note: To exit iex just CTRL+C twice.

Within the shell we can simply type in code on a line and press enter to evaluate it. So for example type 

le = [1,10,20]

press enter and the shell will display the list now bound to the value l.

Now type

length(l)

and the shell should display 3, the length of the list.

To get help from the shell, execute 

h()

Compiling a module into iex

Whilst you’re developing your modules you might which to test them via the shell, in which case from you can load it when you start iex using (in this case my module in called math.ex)

iex math.ex

or if you’ve already started iex, simple use

c "math.ex"

The line above compiles your code and loads into iex so it’s now available to call from the shell.

If you want to view the exports on a module (in this example on my Math module), use the command

exports(Math)

Running PowerShell in a Windows container

I was messing around with Windows based docker images, running IIS and an ASP.NET 4.7.x application and wanted to connect to it’s “shell” to explore what was installed etc.

For Linux container you’ll probably use bash. From a Windows container we can just use powershell

Just change “the-container-id” to the id of the container you wish to connect to

docker container exec -it the-container-id powershell

What’s the purpose of the lang attribute in HTML ?

When creating an an HTML document, we would include the lang attribute to specify the language of the content within the document.

This allows browsers, screen readers etc. to correctly interpret and present content and allows screen readers to pronounce words in the style of the language selected. So for example we’d have

<!DOCTYPE html>
<html lang="en">
  <!-- content -->
</html>

Note that we use the short form language, i.e. “en” or long form such as “en-GB” or “en-US”

Obviously this would need to be changed if your application support i18n, so we might use something like the following, if we’re using something like the i18n package for React

document.documentElement.lang = i18n.language;

// OR

document.documentElement.lang = i18n.resolvedLanguage;

If you do not set the lang or set it to an empty string this simply means the language is unknown.

Whilst this post talks about the html tag, you can actually set the lang on other elements, such as paragraphs p so on a per element basis.

Creating a static web site on Azure (includes Blazor WebAssembly sites)

Azure offer a free static web site option, the process for creating a static web site is the same as creating one for a Blazor standalone application…

  • Create a resource group and/or select an existing one
  • Click Create button
  • Select or search for Static Web App via the marketplace
  • Click Create
  • I’m using the free hosting plan – so click Free, For hobby or personal projects plan type
  • I want the code to be deployed automatically from github, so ensure GitHub deployment details is set up
  • If you need to amend the GitHub account, do so
  • Set your organization, repository and branch to the github account/repo etc.
  • In Deployment configuration I use Deployment Token
  • In Advance, set your region

As part of this process, if you tie to application to your GitHub repo. you’ll also find a GitHub action’s CI/CD pipeline added to your repository which will carry out continuous deployment upon commits/merges to your main branch.

It’s likely you’ll want to map your Azure website name to DNS, I have my domain created with a different company so need to change DNS records

In Azure in the static web app, select Settings | Custom domains and Add Custom domain on other DNS (if host is not in Azure)

  • Type the url name, i.e. www.mywebsite.co.uk or my subdomain is using app.mywebsite.co.uk
  • Azure will create the e CNAME record (which I’ll show below)
  • Click Next then Add (having copied your CNAME values

In my third party host I enter DNS record

  • CNAME
  • app (or www in most cases)
  • your Azure website name (I have to have the url terminated with a .)

Is my ASP.NET core application running in Kubernetes (or Docker) ?

I came across a situation where I needed to change some logic in my ASP.NET core application dependant upon whether I was running inside Kubernetes or an Azure Web app, luckily there is an environment variable that we can use (and whilst we’re at it, there’s one for Docker as well)

var isHostedInKubernetes = 
   Environment.GetEnvironmentVariable("KUBERNETES_SERVICE_HOST") != null;
var isHostedInDocker = 
   Environment.GetEnvironmentVariable("DOTNET_RUNNING_IN_CONTAINER") == "true";