I have been trying out htmx with Kotlin and http4k. To use htmx, you need some way of generating HTML on the server. In Kotlin, you have plenty of options, both Kotlin specific ones and everything from the broader Java/JVM ecosystem. There are two main categories here, template languages and internal DSLs. Given Kotlin’s good support for internal DSLs, I decided to explore that route, and try kotlinx.html and HtmlFlow. They both make great promises of encoding the entire HTML standard and enforce valid HTML at compile time.

I am using PostgreSQL from a Kotlin (JVM) application with the pgJDBC driver. According to the documentation, you can get results from a query based on a cursor to avoid loading the whole result set into the application’s memory at once by calling the setFetchSize() method with a positive value on the Statement before issuing the query. I had a non-trivial query which generated a lot of rows (several thousands), and I only needed the first hundred or so.

You can do quite a lot with Docker, but sometimes you want greater capabilities or increased security, then a proper virtual machine with KVM is a good alternative. An example is when you want to run Docker containers in the VM, it’s not easy to nest Docker without forgoing all security. Just like Alpine Linux is suitable as a base for Docker images, it is also a good option as a guest in a virtual machine.

As I have explained earlier, I am using Leafpad instead of gedit in my Ubuntu system. However, recent versions of Ubuntu does not have Leafpad available through APT any longer, you have to install it with Snap instead. This is quite annoying, since the Snap packaging of Leafpad is too restrictive, it cannot access hidden files in your home directory, nor anything in ~/bin/. This is not good, since I often want to use Leafpad to edit such files.

I have used self-hosted WordPress for this blog since its start in 2006, but I finally got fed up with having to frequently update WordPress itself and a bunch of plugins, or having to constantly worry about security issues. Since I am the only one publishing on this blog, I decided to switch to a static site generator instead, and I chose Hugo, mainly because it is easy to install and does not require any heavy runtime (most of its competitors require Python, Ruby or Node.

I have written about how to configure screen in XTerm to support Ctrl-Tab and convenient scrolling back in history. This has worked well for over a decade now, but it seems like screen is not developed very much any longer, and tmux has gained popularity as a more modern and actively developed alternative. So I decided to try it, and was able to replicate my setup with tmux instead of screen.

I have written about using an embedded database like HSQLDB or H2 for testing Java applications. This can still be useful (although JavaEE is not so popular any longer). But even though H2 claims to emulate PostgreSQL and several other popular production SQL databases, sometimes your application uses very specific features of a particular database and you need to test against the real thing to be really sure your application works correctly.

I have been using the distroless Docker base images to package my applications, mainly since I want slim and simple image without unnecessary cruft. However, they are based on Debian, and Debian is unfortunately not so diligent to fix serious security issues as other distributions like Ubuntu or Alpine. If you scan a distroless image with the grype tool, you get this result: $ grype gcr.io/distroless/java17-debian11 NAME INSTALLED FIXED-IN TYPE VULNERABILITY SEVERITY libharfbuzz0b 2.

Docker’s official documentation on how to enable multi-platform Docker builds is a bit intimidating, suggesting you to run the Docker image tonistiigi/binfmt in privileged mode on your machine. I searched for alternatives on Ubuntu, and found this very detailed description. However, with recent versions of Ubuntu and Docker, it is now much easier than that: Install QEMU’s static user mode emulation binaries: sudo apt install qemu-user-static Install Docker Engine with Buildx support according instructions here (do not install docker-ce or docker.

Sometimes you want to verify that your program actually logs what it is supposed to be logging. When using Apache Log4j 2 as logging framework, it can be done like this: Include this dependency (for Maven, adjust appropriately for other build systems): <dependency> <groupId>org.apache.logging.log4j</groupId> <artifactId>log4j-core</artifactId> <type>test-jar</type> <scope>test</scope> </dependency> Import some stuff: import org.apache.logging.log4j.core.Logger; import org.apache.logging.log4j.core.LoggerContext; import org.apache.logging.log4j.test.appender.ListAppender; Add a ListAppender to the logger you are interested in: var loggerContext = LoggerContext.