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UCARP and High Availability

2020-02-07 2 min read Technology Open-Source Ronny Trommer
If you have ever played with BSD you probably ran into CARP. It allows you to build a high available service which is provided by two physical servers behind a virtual shared IP address. The CARP nodes define a master and a backup system. A master serves the content and if the master crashes, the backup system takes over automatically the virtual IP (VIP) and the client won’t notice. Disclaimer: You should be aware this setup will not share load and increase your network throughput. Continue reading

Docker build and cache invalidation

2019-05-15 3 min read Container Technology Ronny Trommer
Right now I’m working with my work mates @opennms integrating the docker image building in our CI/CD environment. We build our container image based on CentOS and we noticed the caching doesn’t work for ${reasons}. Running a docker build -t myimage . ended up always in installing packages from the official yum repositories even we haven’t changed anything in the Dockerfile. To understand things better, I went back to drawing board and started with a simple example and rebuilding things step by step to understand when gets the docker build cache unnecessarily invalidated. Continue reading

Docker, Java, Signals and Pid 1

2019-02-20 9 min read Container Technology Ronny Trommer
Running a Java application in a container seems to be very easy. The devil is in the details and I want to shed some light on the PID 1 problem when you run Java applications in containers. In a general running applications in containers should not have any state so you just don’t care, but reality is different forces you to have to. Signals are used to a running process to behave in a certain ways. Continue reading

SSL and Java

2018-11-26 3 min read Tutorial Technology Ronny Trommer
Running applications with a current Java is not a big deal thanks Let’s Encrypt. This article describes what happens if you want to authenticate your OpenNMS against LDAP using SSL with a self-certified certificate. First of all I assume you have confiured verything so you can authenticate against LDAP in plaintext and you got a role mapping as you wanted it. If not you can have a look here. So the naive approach would be, just changing the line in your activeDirectory. Continue reading

Everyone can change it and why you shouldn't

2018-09-27 3 min read Open-Source Technology Ronny Trommer
Open Source software is great. If there is something you don’t like, you can at least - try to change it. A lot of Open Source software out there is not primarily used by private people. There are many companies who provide professional services around Open Source software. Some of them try to enhance the appearance with custom User Interfaces, their company logo to fit their own Corporate Identity. There are several motivations, mostly they want to be distinguished on the marked or need some easy to maintain little customization which allows their sales guys easier to sell a project and not using the software from the community projects website. Continue reading

Guidance to Survive Monitoring

2018-08-08 5 min read Technology Open-Source Ronny Trommer
While working in the monitoring field for a long time, here are some rules I try to follow when requirements go awry. Rule #1: Only create an alert when human interaction is required When you setup a monitoring, it tends to get noisy very quickly. The problem is, people want to know everything and want to monitor everything. You tend to build a system which sends you a lot of alarms and you will get alarm fatique. Continue reading

He's dead, Jim

2018-07-30 5 min read Technology Ronny Trommer
If you operate networks there is a big chance you had to deal with SNMP - the Simple Network Management Protocol. If you ever wondered where it came from, it started with a big bang. On October 27, 1980, there was an unusual occurrence on the ARPANET. For a period of several hours, the network appeared to be unusable, due to what was later diagnosed as a high priority software process running out of control. Continue reading

Hipster vs. Microsoft

2018-06-07 3 min read Technology Open-Source Ronny Trommer
This week was great, Microsoft bought GitHub! All the Hipsters went crazy and a lot of open source people move now their repos to GitLab. There is even a Hashtag #movingtogitlab floating around. The GitLab importer showed significant peaks when the news broke out. What the hell happened? GitHub is the new SourceForge GitHub was cool, it made Git to shine. GitHub was the platform to collaborate on software development in public and helped to make Git the de-facto standard as a free and decentralized version control system. Continue reading

Monitoring DevOps and the Status Quo

2017-03-09 5 min read Technology Ronny Trommer
As most of us noticed a few companies changed our perspective how to develop software and deploy them as a service. There are quite a few changes between selling every year a box with 10 CD’s and develop and deliver your software as a service. This article is a collection of thoughts and ideas I had and wanted to be written. Who cares about a version number? User give a shit about version numbers anymore, all what matters needs to be focused on the user. Continue reading

Zyxel vs. Vodafone Easybox with VDSL 50

2016-07-14 1 min read Tutorial Technology Ronny Trommer
I ran in some trouble with my Vodafone Easybox 904 xDSL. Even with 2Ghz and 5Ghz WLAN I had regularly drops. Had to turn on / off the WLAN on the device or had to reboot it to reconnect. Otherwise the VDSL line reguarly got disconnected, also replacing the Easybox from Vodafone didn’t helped, so I bought a Zyxel VMG1312-B30A. Search through the interwebs and took me a while to figure out what settings are required. Continue reading
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