Using shorter UUIDs

UUIDs make great identifiers – ones that are, for most practical purposes, unique, easy to generate, and hard to guess. The only problem is that they are long – 256 bits, but with a textual representation that’s 36 characters. So what if they were shorter?

Continue reading “Using shorter UUIDs”

Configuring a Multi-Branch Pipeline in Jenkins – Adventures in Learning

In my previous post, I had demonstrated how to configure a Jenkins Server using Docker. The next step is to create a Jenkins job to build some software. Now, we could just do a simple freestyle job, or a basic Maven build – but that will require configuration of Jenkins every time we want to make a new project, and that makes managing the Jenkins Server via Docker more annoying. So, instead, I’m going to use the Cloudbees Bitbucket Branch Source Plugin and create a Bitbucket Team/Project job that will create the rest of my Jenkins jobs automagically for me. A similar plugin exists for GitHub, though I haven’t looked into it.

Continue reading “Configuring a Multi-Branch Pipeline in Jenkins – Adventures in Learning”

Setting up a Jenkins Server with Docker – Adventures in Learning

With the upcoming end-of-life for Bamboo Cloud, I’m in the market for a new build server setup. For this1 experiment, I’m returning to an old favourite – Jenkins – paired with a potential new favourite – Docker. In this post, I describe how I’ve set up a Jenkins server in a Docker container, using the Multibranch Pipeline plugin to automatically configure a simple build2.

Continue reading “Setting up a Jenkins Server with Docker – Adventures in Learning”

Object equality is context sensitive

Equality is context sensitive. It’s very rarely as cut-and-dried as people think it is.

As a simple example, consider two $5 notes. I think everyone can agree that these notes have the same value – they are both worth $5. But are they equal?

Continue reading “Object equality is context sensitive”

Immutable objects the lazy way

Building properly immutable objects in Java can be annoying, especially if they’ve got a bunch of properties – too many to put into a readable constructor.1

You can implement the Builder pattern, but a lot of the time that just feels like overkill. But you don’t want to put in a bunch of setter methods, because that’s just asking for trouble. So what do you do?

Continue reading “Immutable objects the lazy way”

Java, Equality, Mutability

TL;DR version: Don’t implement equals() on mutable objects.

This is a post I’ve been tossing around for a couple of years, ever since a lunchtime debate with a colleague. It’s a simple statement: You shouldn’t implement the equals() method if your object isn’t immutable.1

Continue reading “Java, Equality, Mutability”

Example Hadoop Job that reads a cache file loaded from S3

I had all sorts of problems getting my head around how cache files work with Hadoop. Finally, I stumbled across the answer – when you add a cache file (see HadoopMain#48), it’s available to read as a local file inside the mapper (MyMapper#36).

When running in Elastic MapReduce, the file URI can be an S3 file, using either s3://bucket/path or s3n://bucket/path – this may or may not work in other Hadoop implementations, but the general approach would work fine.

See the gist at https://gist.github.com/twasink/8813628

How-To: Grails, GORM and SimpleDB

I went to build a new Grails-based app today, and I wanted to use SimpleDB as a backend (the app is an internal-use administration app, to configure a suite of AWS-deployed apps). So I went looking on how to use GORM with SimpleDB. This turned out to be a non-trivial task, so I thought I’d share the process with everyone.

Continue reading “How-To: Grails, GORM and SimpleDB”

Building Dependent Maven Projects in Bamboo

For the last year or so, I’ve been using Atlassian’s Bamboo (in the OnDemand variant) for our team’s build server. And, mostly, it’s an awesome tool. Some parts, however, are a little rough around the edges. Building dependent projects is one of them.

Continue reading “Building Dependent Maven Projects in Bamboo”

AiL – JBehave and Spring

Having succeeded in getting a simple JBehave story running. my next challenge is to scale it up a bit. In particular, I want to get a JBehave story that integrates with Spring to do something more fully-featured: save an entry in a database.

Continue reading “AiL – JBehave and Spring”