SSL: Man in the middle? – No, thank you!

XFS: Possible Memory Allocation Deadlock in kmem_alloc

A few weeks ago we were surprised by seemingly random I/O hangs on several virtual machines. Any attempt to write to their data volumes blocked, making the load average rise into the stratosphere, and — slightly more consequentially — make Elasticsearch...

• Cloud
• DevOps
• Infrastructure

10.4.2017 | 10 minutes reading time

True KVM Live Migration with OpenStack Icehouse and Ceph based VM storage

Intro As mentioned before — for example in Fabian’s The CenterDevice Cloud Architecture Revisited post from December 2014) — our document management product CenterDevice runs on top of infrastructure virtualized by OpenStack. Where that older post...

• Cloud

16.3.2015 | 12 minutes reading time

Rate Limiting based on HTTP headers with HAProxy

Recently we had a problem with a buggy update to a piece of 3rd party client software. It produced lots and lots of valid, but nonsensical requests, targeting our system. This post details how we added a dynamic rate limiting to our HAProxy load balancers...

3.12.2014 | 7 minutes reading time

Localizing Mobile Apps

What do the acronyms I18N or L10N stand for? What do they mean for developers of mobile applications in particular? I hosted a session about localizing mobile applications at Developer Week 2014 in Nuremberg. It covers — among other things — text, numbers...

26.8.2014 | 1 minutes reading time

Jinja2 for better Ansible playbooks and templates

There have been posts about Ansible on this blog before, so this one will not go into Ansible basics again, but focus on ways to improve your use of variables, often, but not only used together with the template module, showing some of the more involved...

24.8.2014 | 11 minutes reading time

Ansible: Simple yet powerful automation

Automatic provisioning of infrastructure as well as deployment is a cornerstone of DevOps. It brings the benefits of version control, reproducibility, and a central place to consolidate (executable) knowledge about infrastructure setups. Best known provisioning...

• CI/CD
• DevOps
• Infrastructure

22.6.2014 | 14 minutes reading time

SSH Two-Factor Authentication with Duo Security

An ever increasing number of services start offering (and recommending) additional means of securing access to your accounts: Instead of just asking users to identify and authenticate themselves with a simple set of username and password, a second piece...

10.3.2014 | 7 minutes reading time

Pseudo-Localization for Cocoa Apps

Locali… what? Simply speaking, localizing an application means translating all output it produces on the screen (and printouts etc.) to the language of the people using it. There is more to it, though, than a simple translation of messages. You should...

• Java
• iOS
• Software development

23.10.2013 | 14 minutes reading time

Easier JBehave steps with variants

In an earlier post we offered an introduction to the JBehave project for automatic acceptance testing. While that article focused on setup and general use of the framework, this time I will concentrate on a recent addition I wrote and contributed to...

• Agile
• Java

1.4.2012 | 4 minutes reading time

Why good metrics values do not equal good quality

Quite regularly, codecentric’s experts perform reviews and quality evaluations of software products. For example, clients may want to get an independent assessment of a program they had a contractor develop. In other cases, they request an assessment...

• Agile methods
• Java

3.10.2011 | 7 minutes reading time

Using JMeter to measure binary protocols

In a recent project I developed a bridge component to connect a backend web service with a credit-card terminal. The terminal can only speak a binary protocol. The bridge needs to map the binary messages to the corresponding backend calls. If you are...

• Java
• APM

9.5.2011 | 6 minutes reading time