Connect Spring Cloud Stream With Kafka Binder to Azure Event Hub

5. March 20231. April 2023 Robert Lohr2 Comments

In two previous blog posts, I explained how to create a Kafka consumer and producer with the Spring Cloud Stream framework. In the Famous Last Words section of the producer, I already hinted at the notion of utilizing this technology for connecting to Azure Event Hub. While doing so, I discovered an error in one of Microsoft’s examples that has cost me about two days of work. I show you how to avoid the dreaded “Node -1 disconnected” error.

In this tutorial, I explain how to use the exact same code to connect to Azure Event Hub using a Shared Access Signature Token (connection string) and a Service Principal.

I have good news and bad news. Which one first? The bad? Okay, here we go:

There will not be any code in this tutorial, only YAML configuration.

Now to the good part:

There will not be any code in this tutorial, only YAML configuration.

This is the beauty of Spring Cloud Stream. Granted, I am not even swapping the binder for an Azure-native variant. So why would there be any code changes? But let me say this: I briefly plugged in the Event Hub Binder without changing the code in my research on getting this to work. Even the updates to the config were minimal. A few Event Hub-specific settings, especially the Storage Account for checkpoints, and that was it.

Enough foreplay; let me explain what you likely came here for.

Package Qt6 macOS App Bundle With Translation Files In CMake

19. February 20235. March 2023 Robert LohrLeave a comment

Recently, I wrote about how you can create a macOS app bundle with CMake for a Qt6 application. I omitted the inclusion of translation files, which also required code changes. Well, I figured it out and will briefly explain what I had to do.

In my WorkTracker application, I store the language files in a folder called “l10n” at the project’s root. The first thing to do is instruct CMake to copy the *.qm files to the app bundle’s “Resource” folder. I have done that before for the app icon, and the process is similar for this kind of file.

set(l10n_files
    "${CMAKE_SOURCE_DIR}/l10n/qt_de_DE.qm"
    "${CMAKE_SOURCE_DIR}/l10n/de_DE.qm"
    "${CMAKE_SOURCE_DIR}/l10n/en_US.qm"
)

set_source_files_properties(${l10n_files} PROPERTIES 
    MACOSX_PACKAGE_LOCATION "Resources/l10n")

qt_add_executable(WorkTracker MACOSX_BUNDLE 
    ${worktracker_src} 
    ${app_icon_macos} 
    ${l10n_files})

Define a variable l10n_files that contains all the files.
Tell CMake that these files shall end up in the app bundle, in the “Resources/l10n” folder, to be precise.
Include the files in the call to the qt_add_executable function.

A macOS Finder window showing the contents of the "Resources/l10n" folder in an app bundle.

Now that the translations are part of the bundle, a minor modification to the code tells the application where to find them. The Qt documentation contains a section about using macOS APIs to determine the bundle location. That is not necessary, though. Qt also has a helpful method to achieve the same goal, QApplication::applicationDirPath().

#if defined(Q_OS_LINUX)
    // On Linux the translations can be found in /usr/share/worktracker/l10n.
    auto l10nPath = "/../share/worktracker/l10n/";
#elif defined (Q_OS_WIN)
    // On Windows the translations are in the l10n folder in the exe dir.
    auto l10nPath = "/l10n/";
#elif defined (Q_OS_MAC)
    // On OS X the data is somewhere in the bundle.
    auto l10nPath = "/../Resources/l10n/";
#endif

auto appDir = QApplication::applicationDirPath() + l10nPath;

This method returns the absolute path to the “MacOS” folder inside of the bundle, the folder where the application’s binary is located. Appending /../Resources/l10n/ first navigates up to the “Content” folder (via /..), which is more or less the bundle’s “root” directory, and from there, goes to “Resources/l10n”. Finally, the language files are loaded like on Windows, and the translation works as expected.

I hope this was helpful because I could not find much information on this specific topic.

Thank you for reading.

Pentiment Review – I Recommend 66% Of It (PC & Xbox Series X)

12. February 2023 Robert LohrLeave a comment

It may come to you as a shocker, but I have never played a point & click adventure game, like the well-known Monkey Island series, for example. It is something I know exists and is beloved, yet I never touched it, despite several releases of the franchise being of my time. Pentiment falls into the same game category, and the coverage I follow had high praise for that title.

So, when I got sick recently, I figured this would be a chill game to pass the time while trying to recover.

Package Qt6 App as macOS App Bundle With CMake

4. February 202326. February 2023 Robert Lohr1 Comment

The Qt documentation contains all the necessary pieces to create a macOS app bundle. Some steps require CMake configuration, while others require manual labor, i.e., terminal commands. Ideally, you, the developer, want to automate the whole thing and not enter the commands every time you build a release.

You can do that with CMake, and this How-To will show you what to do. I am taking my WorkTracker application as an example since it isn’t just a little toy with an executable binary. It is a fully functional application I use daily at work (albeit on Windows) with icon resources, language files, and several Qt libraries and plugins.

Note: I will not elaborate on the language file topic, as it requires code changes to find the translations in the bundle file. This post focuses on automating the app-bundle creation and setting an application icon.

My Year in Gaming 2022 – Game of the Year and Others

2. January 20235. March 2023 Robert LohrLeave a comment

Last year, I wrote a summary of all the games I played in 2021. It was one of the ways of coping with the stress I deal with at work. And I like games. And writing. And writing about games. And digressing.

Two does not yet make for a series, but I’d like to continue the idea, and maybe I can turn it into one. So, here is my gaming year 2022 in review. I am not yet confident that I have nailed the format, so this blog post will differ in style from the inaugural version. I will start with a bit of story mode, as I am wont to do. Afterward, I’ll present the games in the order I started (or finished?) them. We’ll see. Lastly, I’ll reveal my Game of the Year in 2022.

AND DON’T YOU DARE JUMP AHEAD WITHOUT READING THE REST!

AD Workload Identity for AKS Pod-Assigned Managed Identity (Cross-Post)

29. November 20223. March 2023 Robert LohrLeave a comment

Managing credentials and other types of access tokens is a hassle. In Microsoft’s Azure Cloud, you can take advantage of Service Principals and RBAC. But even then, a Service Principal requires a password. There is a better solution in Azure called Managed Identity. But how can you employ this feature when your workload runs in AKS? There is a solution, and I’ve explained all you need to know in an article on my employer’s developer blog.

There was this thing called Pod-Managed Identities, but that was pretty elaborate in its setup. Azure Workload Identity is much leaner, making the configuration and usage more straightforward. Managing credentials and connection strings in Kubernetes microservices is a hassle I have disliked from the start. Assigning a Managed Identity to an AKS pod or even a Service Principal and then relying on Azure RBAC can make your life as a developer or IT ops engineer so much more enjoyable.

Visit the blog linked earlier to read the full version. It’ll contain my usual bad jokes and is not censored in any way. I’d post the same article 1:1 on this blog if I had not researched the topic on company time.

I hope it can help you, and thank you for reading.

Spring Boot Push Micrometer Metrics to Prometheus Pushgateway

30. October 2022 Robert LohrLeave a comment

Prometheus, as a metrics solution, gets its data by actively reading it from designated services – a process known as scraping. This approach might not work if your workload contains short-lived tasks, as your task may not fall within the scraping time window.

Luckily, Prometheus has a solution for this: the Pushgateway.

It presents a push-based target for your metrics that itself is scraped by Prometheus. But how do you configure this in a Spring Boot application? Let me show you.

Spring Boot Custom Field Error Messages in Class-Based Custom Bean ConstraintValidator

19. October 2022 Robert LohrLeave a comment

This short guide will focus on a single specific aspect of custom bean validation. If you need to catch up on how to write a custom bean validator, check out the tutorial on reflectoring.io. What is usually missing from these how-tos is the handling of validators for an entire class instead of just a field and how to set custom errors for specific field errors in a class.

Why would you want to write a validator for an entire class?

You may run into a situation where the value of one field of a class depends on the value of another field. For example, the field “type” value impacts which values are valid for the field “content”.

But when you define a custom validator, the validation annotation @interface only represents a single error message. The result is that any field error would result in the same error message. In a web service, this is not very helpful for users of your API.

Uncharted – The Nathan Drake Collection Review (PS4 Pro)

3. October 2022 Robert Lohr1 Comment

If I were to explain to someone how Uncharted plays, I would say that it is like Tomb Raider, only with more shooting, more linear, and a lot more character-building and interaction.

I guess I’m done here. See ya next time. Thank you for reading.

Yeah, no. I am incapable of being that brief. It is 2022, and I am enjoying a game franchise developed initially for the PlayStation 3. The first entry in the series was released fifteen (15!) years ago by Naughty Dog, nowadays of The Last of Us fame. Uncharted 1 Drake’s Fortune debuted in 2007, was followed up in 2009 with Among Thieves, and the trilogy (yes, I am aware there is a part four) was completed in 2011 with Drake’s Deception. I am not really one for nostalgic trips, so I picked up the remastered version instead of the originals (and I do not have a PS3). Bluepoint, now a part of PlayStation Studios, enhanced these three games for the PlayStation 4 and splashed out 60 fps gameplay. Note, though, that the remaster itself is also already seven years old. It was released in 2015.

Kena Bridge of Spirits Review (PC)

18. September 202218. September 2022 Robert Lohr1 Comment

I do not recall when I first became aware of Kena Bridge of Spirits. According to this announcement trailer, it must have been sometime in 2020. I was immediately hooked, but I did not jump in right away when it launched in 2021. I do not even remember why. It was a tough year for me personally, so maybe that was one of the reasons. Whatever it was, I am rarely on time with game releases, so why would Kena Bridge of Spirits be any different?

It is a different game, though (horrible segue *cough*), and one that I think stands out among all the others I have played in the past decade. Kena Bridge of Spirits is a PlayStation and PC exclusive, and it is the first title I played after building a gaming PC after just one year of abstinence. I haven’t heard much of this game after its release. Still, it apparently did well enough for Ember Lab to warrant a free anniversary upgrade at the end of September 2022.

Close combat games aren’t usually my jam. That is not because I do not like them. It has more to do with my inability to master the combat for an enjoyable experience. I must often resort to the Easy difficulty to complete challenging sections or bosses, and in the majority of times, the Easy mode is so accessible that it is borderline boring. Despite that, I went into the game with an open mind, and I am glad I did. I still had trouble with some of the bosses, but for the most part, I fought my way through the game on the normal difficulty. Let me tell you about it.

As always, I begin by discussing the game’s technology.

I Bestow Upon Thee “HotkeyAutoExecute”, My Game Screenshot Automator

21. August 20224. September 2022 Robert LohrLeave a comment

HotkeyAutoExecute is a simple single-window tool that lets you manage a list of frequently used hotkeys, of which one is repeatedly executed in configurable intervals.

That was the TLDR blurp, and now let’s get into the details. This tool scratches an itch I had in 2020 when I wanted to simplify the process of taking game screenshots for my reviews. During intense gameplay moments, it is difficult to focus on the game and press a keyboard shortcut to take an image of on-screen action. Therefore, I hacked something that would do the job but was not quite baked to be open-sourced as an application. I have changed that now, and boy, was it more complicated than I would have liked.

Convert QKeySequence of QKeySequenceEdit to Native Windows Virtual Key Codes VK_*

20. August 2022 Robert Lohr1 Comment

In a blog post in 2020, I described how to utilize the WinAPI SendInput() function to emulate hotkey presses to automatically take game screenshots for my video game reviews. While I intended to create a simple GUI application to do the task, I ended up with only a hack because of a massive boulder that Windows threw in my way. Or after me, chasing me down a narrow path.

Forget the boulder.

(Although it would be a fitting metaphor to describe Windows: tall, fat, and destructive to user privacy.)

I wanted a simple input field where the user can press a key sequence that will be executed repeatedly at an interval. Qt conveniently provides QKeySequenceEdit for this purpose, and when I tried to insert the Xbox Game Bar hotkey, it did not register. Well, it did, in that Windows took a screenshot. But it was not recorded by the widget. Windows seems to intercept and eat the key presses. That was when I decided to just hard-code my needs and call it a day.

Two years later, I figured that it was about damn time to fix this, and this is where I ran into issues with the translation of key codes from QKeySequenceEdit and QKeySequence to native Windows virtual key codes.

This is where our adventure begins.

Spring Boot @RestController Action Returning java.util.Optional

24. July 2022 Robert LohrLeave a comment

Recently, I wondered what would happen if a Spring Boot RestController returned a java.util.Optional instead of a regular POJO.

I invested 30 minutes of my life to find out, and created an over-engineered example on GitHub.

Here is the controller.

@Slf4j
@RestController
@RequiredArgsConstructor
public class MusicController {

    private final MusicService musicService;

    @GetMapping(path = "/value")
    Album getValue(@RequestParam("isNull") boolean isNull) {
        log.info("Request album value (is null: {})", isNull);
        return musicService.getAlbumAsValue(isNull);
    }

    @GetMapping(path = "/optional")
    Optional<Album> getOptional(@RequestParam("isNull") boolean isNull) {
        log.info("Request album optional (is null: {})", isNull);
        return musicService.getAlbumAsOptional(isNull);
    }
}

The first question I had was if Spring Boot would even start up. You never know. It does, and with this hurdle out of the way, here’s the output of a couple of curl commands.

~ % curl -i 'http://localhost:8080/value?isNull=false'   
HTTP/1.1 200 
Content-Type: application/json
Transfer-Encoding: chunked
Date: Sun, 24 Jul 2022 08:24:50 GMT

{"artist":"Insomnium","title":"Winter's Gate","genre":"Melodic Death Metal","year":2016} 

~ % curl -i 'http://localhost:8080/value?isNull=true'    
HTTP/1.1 200 
Content-Length: 0
Date: Sun, 24 Jul 2022 08:24:55 GMT
 
~ % curl -i 'http://localhost:8080/optional?isNull=false'
HTTP/1.1 200 
Content-Type: application/json
Transfer-Encoding: chunked
Date: Sun, 24 Jul 2022 08:25:00 GMT

{"artist":"Insomnium","title":"Winter's Gate","genre":"Melodic Death Metal","year":2016} 

~ % curl -i 'http://localhost:8080/optional?isNull=true' 
HTTP/1.1 200 
Content-Type: application/json
Transfer-Encoding: chunked
Date: Sun, 24 Jul 2022 08:25:06 GMT

null

Everything works as expected except for the null-case with the Optional. It returns the string “null” instead of nothing.

The moral of the story: Do not return java.util.Optional from a @RestController, or you need to do more work to unpack it.