Installing Node Exporter on Linux

In OpenNMS Horizon 28+ is now a PrometheusCollector available. It scrapes the metrics from the provided exporter pages and allows to add data collections. As of speaking today it is not 100% feature complete, scraping data types like histograms is not implemented yet. If you want to play around here is a quick way to get the Linux Node_Exporter installed. The following steps are executed in a root shell with sudo -i. Continue reading

UCARP and High Availability

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

Everyone can change it and why you shouldn't

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

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

Hipster vs. Microsoft

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

Open-source Experience

I spend a lot of time in the OpenNMS project and I love to work in free software and the workflows around it. We moved with our project from SourceForge to GitHub a few years ago and I think it was the right decision. There are now some established workflows in this ecosystem and they tear down borders between different open-source projects and here is an example of it. I develop with IntelliJ IDEA and spend currently some time working in documentation of OpenNMS. Continue reading