OpenEBS provides a Kubernetes native distributed storage solution which is friendly on developers and administrators. It is completely open source and part of the CNCF. Previously I wrote about installing and using OpenEBS, Jiva storage engine, on the Charmed Kubernetes distribution of Canonical. The Jiva storage class uses storage inside managed […]
Maarten Smeets
Maarten is a software architect and Oracle ACE. Over the past years he has worked for numerous customers in the Netherlands in developer, analyst and architect roles on topics like software delivery, performance, security and other integration related challenges. Maarten is passionate about his job and likes to share his knowledge through publications, frequent blogging and presentations.
Production-like Kubernetes on your laptop. Kubespray on KVM
There are various options to install a production-like Kubernetes distribution on your laptop. Previously I tried out using the Canonical stack (Juju, MAAS, Charmed Kubernetes) for this. This worked nicely but it gave me the feeling that it was a bit Canonical specific and it felt a bit heavy on resources at […]
Anchore Engine: Container image vulnerability scanning
Applications nowadays, are usually deployed inside containers. A container consists of libraries and tools which allow the application to run inside. Since there can be exploitable vulnerabilities, it is not only important to take security into account for your application, but also for the container it runs in. There are […]
OBS Studio + Snap Camera: Putting yourself in your presentation live for free!
When giving online presentations, it helps for personal marketing if people can see you on the screen. Various tools provide features which help you achieve that, for example Microsoft Teams. Sometimes though you do not have that available or want to be able to do more than what the tool […]
OpenEBS: Create persistent storage in your Charmed Kubernetes cluster quick and easy!
As a developer I wanted to experiment with Kubernetes environments which approximate production deployments. In order to do that I wanted a distributed storage solution and chose OpenEBS. Mainly because it was easy to get started and quick to get up and running. In this blog post I’ll describe how […]
Charmed Kubernetes on KVM using MAAS and Juju
Coming to this solution was a journey. I was looking for a Kubernetes installation which was easy to deploy and cleanup on my own laptop (I didn’t want to have to pay for a hosted solution). I did want a solution which was more or less production-like because I wanted […]
Quick and easy: A multi-node Kubernetes cluster on CentOS 7 + QEMU/KVM (libvirt)
Kubernetes is a popular container orchestration platform. As a developer understanding the environment in which your application is going to run is important since this can help you use available services of the platform and fix issues. There are several options to run Kubernetes locally to get some experience with […]
Spring: Blocking vs non-blocking: R2DBC vs JDBC and WebFlux vs Web MVC
Spring Framework version 5, released in Sept 2017, introduced Spring WebFlux. A fully reactive stack. In Dec 2019 Spring Data R2DBC was released, an incubator to integrate relational databases using a reactive driver. In this blog post I’ll show that at high concurrency, WebFlux and R2DBC perform better. They have […]
The size of Docker images containing OpenJDK 11.0.6
When running Java applications in containers, you need to be careful with your resources. If you’re not careful with layering your images (for example using Google’s Jib), you can quickly get into disk-space issues, especially when your base image and/or application gets updated regularly. One of the ways you can save […]
Performance of relational database drivers. R2DBC vs JDBC
R2DBC provides non-blocking reactive APIs to relational database programmers in Java. It is an open specification, similar to JDBC. JDBC however uses a thread per connection while R2DBC can handle more connections using less threads (and thus potentially use less memory). This could also mean threads are available to do other […]
Secure browsing using a local SOCKS proxy server (on desktop or mobile) and an always free OCI compute instance as SSH server
Oracle provides several services as ‘always free’. In contrast to Azure and Amazon, these include compute instances which remain ‘forever’ free to use. Although there are some limitations on CPU, disk, network resources, these instances are ideal to use as a remote SSH server and with a little effort a […]
HTTP benchmarking using wrk. Parsing output to CSV or JSON using Python
wrk is a modern HTTP benchmarking tool. Using a simple CLI interface you can put simple load on HTTP services and determine latency, response times and the number of successfully processed requests. It has a LuaJIT scripting interface which provides extensibility. A distinguishing feature of wrk compared to for example ab […]
pgAdmin in Docker: Provisioning connections and passwords
pgAdmin is a popular open source and feature rich administration and development platform for PostgreSQL. When provisioning Postgres database environments using containers, it is not unusual to also provision a pgAdmin container. The pgAdmin image provided on Docker Hub does not contain any server connection details. When your pgAdmin container […]
Apache Camel + Spring Boot: Different components to expose HTTP endpoints
Apache Camel is an open source integration framework that allows you to integrate technologically diverse systems using a large library of components. A common use-case is to service HTTP based endpoints. Those of course come in several flavors and there is quite a choice in components to use. In this blog post […]
Java Microservices: What do you need to tweak to optimize throughput and response times?
Performance tuning usually goes something like followed: a performance problem occurs an experienced person knows what is probably the cause and suggests a specific change baseline performance is determined, the change is applied, and performance is measured again if the performance has improved compared to the baseline, keep the change, […]
Oracle Database: Write arbitrary log messages to the syslog from PL/SQL
Syslog is a standard for message logging, often employed in *NIX environments. It allows separation of the software that generates messages, the system that stores them, and the software that reports and analyzes them. Each message is labeled with a facility code, indicating the software type generating the message, and assigned […]
Calling an Oracle DB stored procedure from Spring Boot using Apache Camel
There are different ways to create data services. The choice for a specific technology to use, depends on several factors inside the organisation which wishes to realize these services. In this blog post I’ll provide a minimal example of how you can use Spring Boot with Apache Camel to call […]
Microservice framework startup time on different JVMs (AOT and JIT)
When developing microservices, a fast startup time is useful. It can for example reduce the amount of time a rolling upgrade of instances takes and reduce build time thus shortening development cycles. When running your code using a ‘serverless’ framework such as for example Knative or FnProject, scaling and getting […]
Apache Camel and Spring Boot: Calling multiple services in parallel and merging results
Sometimes you have multiple services you want to call at the same time and merge their results when they’re all in (or after a timeout). In Enterprise Integration Patterns (EIP) this is a Splitter followed by an Aggregator. I wanted to try and implement this in Spring Boot using Apache Camel so I […]
A transparent Spring Boot REST service to expose Oracle Database logic
Sometimes you have an Oracle database which contains a lot of logic and you want to expose specific logic as REST services. There are a variety of ways to do this. The most obvious one to consider might be Oracle REST Data Services. ORDS is quite powerful and for example supports […]
Graceful shutdown of forked workers in Python and JavaScript running in Docker containers
You might encounter a situation where you want to fork a script during execution. For example if the amount of forks is dependent on user input or another specific situation. I encountered such a situation in which I wanted to put load on a service using multiple concurrent processes. In […]
Performance! 3 reasons to stick to Java 8 for the moment
It is a smart thing to move to newer versions of Java! Support such as security updates and new features are just two of them but there are many more. Performance might be a reason to stick to Java 8 though. In this blog post I’ll show some results of […]
6 tips to make your life with Vagrant even better!
HashiCorp Vagrant is a great tool to quickly get up and running with a development environment. In this blog post I’ll give some tips to make your life with Vagrant even better! You can find an example which uses these tips here.
Filesystem events to Elasticsearch / Kibana through Kafka Connect / Kafka
Filesystem events are useful to monitor. They can indicate a security breach. They can also help understanding how a complex system works by looking at the files it reads and writes. When monitoring events, you can expect a lot of data to be generated quickly. The events might be interesting […]
Minikube on KVM on Linux Mint 19.1
In a previous blog post I wrote about running Minikube on Windows. I ended with the suggestion that getting Minikube working might be much easier on Linux. Thus I installed Linux Mint (as dual-boot) on my laptop and gave it a shot. The steps I took to get it working […]
Minikube on Windows. Hyper-V vs Vagrant/VirtualBox
Kubernetes is a system for running and coordinating containerized applications across a cluster of machines. Minikube runs a single-node Kubernetes cluster and can be used for local development. In this blog post I’ll compare 2 different ways to get a working Minikube environment on Windows based on experience with a […]
JVM performance: OpenJ9 uses least memory. GraalVM most. OpenJDK distributions differ
In a previous blog post I created a setup to compare JVM performance of several JVMs. I received some valuable feedback on the measures I conducted and requests to add additional JVMs. In this second post I’ll look at some more JVMs and I’ve added some measures like process memory […]
Comparing JVM performance; Zulu OpenJDK, OpenJDK, Oracle JDK, GraalVM CE
There are many different choices for a JVM for your Java application. Which would be the best to use? This depends on various factors. Performance being an important one. Solid performance research however is difficult. In this blog I’ll describe a setup I created to perform tests on different JVMs […]
Monitoring Spring Boot applications with Prometheus and Grafana
In order to compare the performance of different JDKs for reactive Spring Boot services, I made a setup in which a Spring Boot application is wrapped in a Docker container. This makes it easy to create different containers for different JDKs with the same Spring Boot application running in it. […]
Running Reactive Spring Boot on GraalVM in Docker
GraalVM is an open source polyglot VM which makes it easy to mix and match different languages such as Java, Javascript and R. It has the ability (with some restrictions) to compile code to native executables. This of course offers great performance benefits. Recently, GraalVM Docker files and images have […]
Securing Oracle Service Bus REST services with OAuth2 client credentials flow (without using additional products)
OAuth2 is a popular authentication framework. As a service provider it is thus common to provide support for OAuth2. How can you do this on a plain WebLogic Server / Service Bus without having to install additional products (and possibly have to pay for licenses)? If you just want to […]
Docker host and bridged networking. Running library/httpd on different ports
Docker provides different networking options. When using the Docker host networking, you don’t have the option to create port mappings. When using images like library/httpd:2.4, you don’t have the option to update the port on which it runs; it runs by default on port 80. Suppose you want to use […]
Running Spring Tool Suite and other GUI applications from a Docker container
Running an application within a Docker container helps in isolating the application from the host OS. Running GUI applications like for example an IDE from a Docker container, can be challenging. I’ll explain several of the issues you might encounter and how to solve them. For this I will use […]
Automate the installation of Oracle JDK 8 and 10 on RHEL and Debian derivatives
Automating the Oracle JDK installation on RHEL derivatives (such as CentOS, Oracle Linux) and Debian derivatives (such as Mint, Ubuntu) differs. This is due to different package managers and repositories. In this blog I’ll provide quick instructions on how to automate the installation of Oracle JDK 8 and 10 on […]
VirtualBox networking explained
VirtualBox networking is extremely flexible. With this flexibility comes the challenge of making the correct choices. In this blog, the different options are explained and some example use cases are elaborated. Access between guests, host and other members of the network is explained and the required configuration is shown. This […]
How to securely access remote content without using a VPN: Use a proxy server accessed through an SSH tunnel
There are numerous occasions that I was limited in my work because of connectivity which could not be trusted. For example; I could not download large installers due to a proxy anti virus tool which manipulated downloads causing files to become corrupted. I needed to visit a website to find […]
SOA Suite 12c in Docker containers. Only a couple of commands, no installers, no third party scripts
For developers, installing a full blown local SOA Suite environment has never been a favorite (except for a select few). It is time consuming and requires you to download and run various installers after each other. If you want to start clean (and you haven’t taken precautions), it could be […]
Running Spring Boot in a Docker container on OpenJDK, Oracle JDK, Zulu on Alpine Linux, Oracle Linux, Ubuntu
Spring Boot is great for running inside a Docker container. Spring Boot applications ‘just run’. A Spring Boot application has an embedded servlet engine making it independent of application servers. There is a Spring Boot Maven plugin available to easily create a JAR file which contains all required dependencies. This […]
Application Container Cloud Service (ACCS): Using the Application Cache from a Spring Boot application
Spring Boot allows you to quickly develop microservices. Application Container Cloud Service (ACCS) allows you to easily host Spring Boot applications. Oracle provides an Application Cache based on Coherence which you can use from applications deployed to ACCS. In order to use the Application Cache from Spring Boot, Oracle provides […]
Java: How to fix Spring @Autowired annotation not working issues
Spring is a powerful framework, but it requires some skill to use efficiently. When I started working with Spring a while ago (actually Spring Boot to develop microservices) I encountered some challenges related to dependency injection and using the @Autowired annotation. In this blog I’ll explain the issues and possible […]