Collection of old coins
Ethereum, Solidity

ERC20 TOKEN 

Do you want to create your own ERC20 token on Ethereum? Here we program one and learn more on solidity while we’re at it. Tokens can be used for all kinds of things, not only to fuction as a currency. In future posts we will…

Collection of test bottles
Docker, Java, Spring Boot

TESTCONTAINERS 

Are you struggling finding the right strategy for your integration tests? Mocking does not cover everything and relying on all external services to be present also gives you a headache. What if there was a way to start the real service in your integration tests?…

Two men walking on ridge
Command line, Java

PICOCLI 

Do you want to bring your java applications to your command line? Picocli is a framework that enables you to create your own rich CLI ,backed by java! In this post we will get started with an example CLI called java-genie. To read more on…

Open journal with written text
Java, Micronaut, Ops

ZALANDO LOGBOOK 

Do you need http request and response logging without it polluting your business code? Use Zalando Logbook and add this aspect to your stack! In this post we will add logging for all http requests and play around with the configurations. For more in depth…

Collection of tiny houses
Docker, Java

UPX IMAGE 

Do you want smaller images with a faster startup time? Use UPX to compress your executable inside your image. Use a UPX image! For more information on the internals of UPX take a look at their website here. Or at the source code of UPX…

Sailboat on a blue sea
Docker, Java

JIB MAVEN PLUGIN 

Do you need a simple way to build docker images for your java with maven applications? Use the jib maven plugin and let maven do the heavy lifting! For a complete overview of all capabilities of the jib maven plugin take a look at the…

Native peruvian lady
Docker, Micronaut

NATIVE IMAGE 

Are you looking for a way to build super fast starting images with a low memory footprint? Use GraalVM’s native image and make the difference! To skip the details on when building a native image is possible we will use a framework that advertises with…

Archaic head on wall
CI/CD, Java

MAVEN ARCHETYPE 

Are you copying an old maven project every time you need a new one? Maybe a maven archetype is the solution for you! In this post we will create a maven archetype to quickly create a micronaut graphQL API. A different guide on how to…

Collection of test tubes
gRPC, Java, Micronaut

MICRONAUT TESTING 

Having trouble testing your micronaut application? Or just interested on my take on micronaut testing? Just read along! In this post we will make some integration and unit tests for a micronaut gRPC API. For a wider view of the micronaut testing capabilities look at…

Part of race track
CI/CD, Git

JGITVER 

Are you looking for an easy way to handle versioning of your maven projects? Use the jgitver maven plugin! In this post we will setup the plugin and show some of the main features. For a complete overview of the plugin and its workings please…

Graph of green wires
GraphQL, Micronaut

GRAPHQL WITH MICRONAUT 

Are you working around the clock creating new REST endpoints for you clients? Are the requirements constantly changing? Use graphQL with micronaut and give more control to the client. The graphQL website is a great place to start reading. Also the tutorial by micronaut on…

Trees on an island
gRPC, Micronaut

GRPCURL 

Are you looking for an easy way to test your gRPC endpoints? Use gRPCurl from the command line and see the result in Json. It’s basically curl for gRPC endpoints. In this post we will explore my method of exploratory testing a gRPC server. The…

Lanscape of plain and sky
gRPC, Java, Micronaut

GRPC WITH MICRONAUT 

Are you sick of writing client libraries for all your clients? Do you have trouble sticking to a contract-first approache with REST? Use gRPC! Specifically gRPC with micronaut! To get familiar with micronaut check out this previous post on micronaut. The complete code for this…

Chocolate truffles
Ethereum, Solidity

TRUFFLE SUITE 

Do you want to publish smart contracts on the Ethereum blockchain? We are going to use the Truffle suite to deploy our first! In this post we are going to build a trust fund holder where you can release funds to someone after a set…

Fluent sea waves
Cloud, Docker, Helm, Kubernetes, Ops

FLUENT 

Are you sick of going into a Kubernetes cluster to look at the logs of an application? Do you want a clear overview of the access logs over several pods? Use these tools for a fluent log experience. We are going to use fluent-bit, fluentd,…

Deer in the woods
Docker

CONTAINER SECURITY 

Are you writing secure Dockerfiles? Are you scanning for security vulnerabilities of the base images you use? Use hadolint and trivy to upgrade your container security! We are going to explore two tools for writing better and more secure images: hadolint (code here on github)…

Man gazing up to the stars
Kubernetes

KUBECTL TOOLS 

Are you tired of typing the namespace in every kubectl command? Do you keep forgetting the command for switching the kubectl context? Speed up your kubectl process with these kubectl tools! I am refering to the tools that come with kubectx. Installation On macOS I…

Construction workers
CI/CD, Cloud, Micronaut

TRAVIS CI 

Looking for a free and easy way to build your open source projects? Travis CI enables you to build, test and deploy your code in minutes! In this post we will setup a Travis CI build to get you going quickly. For a complete overview…

Chapel with cypresses
Angular

E2E TESTS WITH CYPRESS 

Are you looking for a developer friendly end-to-end framework for your Angular projects? Create your e2e tests with Cypress! In this post we will get started with Cypress and create our first e2e test for an example angular project. For a more information on all…

Filing cabinet
Java, Spring Boot

OAS3 AND SPRING BOOT 

Looking for an easy way to document your Spring Boot API following the OAS3 specification? Use a Springdoc documentation endpoint, for OAS3 and Spring Boot! In this post we set up Springdoc and add documentation to an example endpoint. The code for the Springdoc project…

Jest card
Angular

ANGULAR WITH JEST 

Do you ask yourself if there is a better testing framework for your Angular applications? Use Angular with Jest and make your tests simpler and faster! In this post we migrate an example project and discuss the main advantages I found. Take a look at…

Intercepting rugby ball
Angular

ANGULAR HTTP INTERCEPTOR 

Do you need control over all http requests of your app at once? Use an Angular http interceptor for incoming or outgoing http! In this post we will add a api-key header to all outgoing http requests and navigate to the login page for all…

Two houses with different colors
Angular

NG-APIMOCK 

Are you looking for a way to mock api calls for your Angular app? Do you want to test different responses locally? Here is ng-apimock! In this post we are going to setup api mocking in a very simple app so you can see what…

Locks on steel wire
Ops

GPG ENCRYPTION 

Do you feel lost when others talk about encryption? In this post we will get you started with GPG encryption and encrypt/decrypt our deepest secrets. We will install the gpg commandline tool to do so. GNU Privacy Guard (GPG) is an implementation of the OpenPGP…

Lit up turning table
Ethereum, Solidity

ETHEREUM REMIX 

Don’t want to install stuff to get started creating smart contracts on the Ethereum blockchain? Use Ethereum remix to create and test your smart contracts! In this post we go over the basic functionalities of remix so you can get started fast. For a local…

Swings on a playground
Cloud, Micronaut, Ops

HEROKU PLAYGROUND 

Do you want to deploy your applications instantly to a cloud environment? Heroku offers a free account to get you started right away! In this post we set up our Heroku playground and deploy an app. You can read more on all other possibilities of…

Hexagon chain of windows
Ethereum

ETHEREUM DEVELOPER 

Are you interested in blockchain development but you don’t know where to begin? In this series we will get started with developing smart contracts on the Ethereum blockchain. Your first step in becoming a Ethereum developer. The goal of this first post is to get…

Compass on a ship
Android, Kotlin

ANDROID NAVIGATION 

An Android app with only one screen can be kind of dull. Here we learn how to switch between screens with Android Navigation. We take on clicklisteners on a recyclerview, passing arguments and the famous back stack. A great way to start your journey into…

Open doors to another room
Android, Kotlin

ANDROID ROOM 

Did you ever consider the users of your app could have no internet connection? Android Room will store data locally enabling a smooth offline experience. In this post we will show how to store data in a Room database and abstract this mechanism away using…

Empty glass bottles for recycling
Android, Kotlin

ANDROID RECYCLERVIEW 

There are a lot of great places where you can get started with Android. In this post we assume you did a tutorial and go from there. We will talk about Recyclerview, ViewModels, Data Binding and more. The place where I started out with Android…

Wall of sowing machines
Java, Spring Boot

SPRING AUTOCONFIGURE 

Ever wondered how defining a property in Spring applications can automatically configure functionality? We are going to create this ourselves with Spring autoconfigure. We are going to setup a controller with endpoint with only a dependency and a property. For a more in depth discussion…

Flower arrangement
Command line

TERMINAL ARRANGEMENT 

Do you find yourself opening terminals and first resizing and arranging them before starting your commands? In this article we look at some helpful shortcuts for arranging one or multiple terminal windows with iTerm2. Personalise your terminal arrangement. For the full documentation on iTerm2 take…

Colour sorted inventory
Freelance, Ops

CHROME SESSIONBOX 

Ever found yourself opening incognito browser screens just to test your application with another account? The chrome sessionbox extension lets you create multiple sessions in separate tabs! Installing is easy via the google chrome webstore found here. Creating a new session First navigate to your…

Concert with lights
Freelance, Ops, Scrum

REVEAL.JS 

In this post we look at reveal.js, a presentation framework from code! We discuss the benefits like importing themes and using i-frames inside the presentation. For a complete overview of all the features of reveal take a look at the README.md on github here. Did…

Running track
Angular

ANGULAR 8 UPGRADE 

It is about time to take on the Angular 8 upgrade. In this post we will see the steps that I needed for this job. In an earlier post we made the Angular 7 upgrade and there are a lot of similarities. Let’s dive into…

Orange smoke bomb
Cloud, Kubernetes, Ops

PROMETHEUS ALERTING 

In an earlier post we saw how to setup a Prometheus instance in our cluster. Here we create alerts on the Prometheus monitoring for when some action is needed on our pods. No need for constant monitoring with Prometheus alerting. For in depth documentation on…

Island in blue lake
Java, Kotlin

JAVA TO KOTLIN 

For Android developers there is a shift going on from Java to Kotlin. Here we are going to look at some Kotlin features that caught my eye. My overall impression is that it’s Java but more concise and more safe. Let’s have a look. For…

Integration web
Angular, CI/CD

NPM CI 

As an Angular developer npm install is a well known command. Copying this command to your Continuous Integration pipeline is a bad idea. Use the npm ci command instead. Here is why. We will concentrate on the differences betwee install and ci. For the complete…

Tree in a field
Command line

TREE COMMAND 

Ever been working your way down directories with alternating ls and cd? Not knowing by heart what the whole directory structure looks like can be a pain. But there is a way out with the tree command! This post is part of a series on…

Pie with meringue
Command line

HTTPIE 

Postman was my go to tool when I considered making a http request. That all changed when I found out httpie gives a very easy and short API precisely for this. In this post I will show why I like httpie. The full documentation can…

Man jumping over the abyss
Command line

Z COMMAND 

Working from the command line can be repetitive. Are you sick of typing the same path to a directory over and over again? Are you sometimes opening a finder to see what this path was? Z to the rescue! Now you can jump to this…

Coi fish
Command line

FISH SHELL 

As I gain more experience as a software developer I find myself using the command line a lot more. With this growing demand comes a growing need for powerful tools for the command line. In comes fish shell. For a complete documentation and installation guide…

Old house in jackson
Java, Spring Boot

JACKSON ANNOTATIONS 

Jackson is a helpful tool when building REST API’s. In this post I will explain what Jackson annotations I use all the time. There are of course many more Jackson annotations for all situations (example tutorials here). Here we focus on the things you want…

Highway to nowhere
Cloud, Kubernetes

KUBERNETES INGRESS 

In previous posts on deploying an application to a Kubernetes cluster we used a NodePort to expose the service to the outside world. Kubernetes Ingress is a separate Pod where we can control this exposure via routing, security and rate limiting. In this post we…

Combiner in wheat harvest
Reactive

RXJS COMBINING 

In this post we show some ways to combine observables. I made a stackblitz example project to give you a working example. The RxJS part of the project will be discussed in this post on RxJS combining. Disabled while loading We start out with 2…

Paper boats with lights
Reactive

RXJS MULTICASTING 

Most of the time you want to do multiple things with data you have. This post is on how to share this data in multiple observables: RxJS multicasting. For more examples on RxJS multicasting got to this learn-rxjs site. Say we have an api call…

Road closed signs
Reactive

RXJS ERROR HANDLING 

Errors are first class citizens in reactive programming. The error flow is adopted as a valid case of all observables. This is an essential and great feature but also one of the less understood parts. In this post we explore some of the most common…

Back and white face paint
Freelance, Git

MULTIPLE GIT USERS 

Ever wanted to commit something with a different git user? Maybe your employer provided a user for you? Here are some strategies. For more detailed information of the commands in this post please visit the git config documentation. Switch git user for one repository Suppose…

Tape measure
Angular

UPGRADING TO ANGULAR 7 

Keeping up with the latest version of Angular is good practise. In this post I will take you through the steps I took with my projects upgrading to Angular 7. You could also take a look at this upgrading tool by Angular to help with…

Chess board
Git

MOVE A GIT REPOSITORY 

This week we moved our git repositories to a new platform used in the company. This operation is simpler than a move from say SVN to git. Still here are some points not to overlook. It is always a good idea to take a closer…

Vats of whine
Freelance

VAT DECLARATION 

As a freelancer you are responsible for your own taxes. Some get an accountant to this but there is not much to it if you break it down. Here we discuss the VAT declaration, BTW in dutch. VAT are the taxes you charge on the…

Child looking at the sea
Angular

ANGULAR VIEWCHILD 

When you want to control a child component, directive or DOM element from its parent component, you can use the Viewchild decorator in Angular. Viewchild returns the first element that matches a give child component, directive or DOM element and updates it if the reference…

Cherries on tree branch
Git

GIT CHERRY-PICK 

Ever been in the situation where you want a change from another branch but not all? I did… and ended up merging everything and reverting all the things I didn’t need. Turns out git has a command for this! Git cherry-pick. The official documentation can…

Internet cables in sockets
Reactive

RXJS FLATTENING 

From functional programming we all know map and flatMap. With reactive programming just flattening is not enough information. We have to make a decision about what to do when either the observables emit the next element or complete. We have the following choices: mergeMap — deciding not…

Lonely tree in middle of a lake
Angular

ANGULAR 6 TREE SHAKING 

Working in reasonably big companies for the last years I’ve come across big Angular projects. As you would expect these projects were modular projects consisting of a bunch of modules. One of the things I never took in consideration was ‘tree shaking’. You can read…

Colorful code
Angular

NPM PEER DEPENDENCIES 

Comming from the java world I realised npm resolves dependencies differently than for example maven. Maven demands one unique version of a dependency amongst who depend on it. This sometimes results in a so called ‘dependency hell’. Here we talk about peer dependencies that come…