Running a private container registry for testing

When I signed up for my DockerHub account in 2013, I never thought sooner than later everything ends up in a container image as it is today. DockerHub was the first public free as in free beer registry to distribute your container images. Containers are now everywhere, and DockerHub, a corporate entity running and funding DockerHub, introduced usage limits for the free tier and started commercializing its registry service. I need to play with software in a micro-service architecture on a platform like Kubernetes, and these limits can be daunting.

SSL and Java

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.xml from

Monitoring Websites with OpenNMS

Monitoring websites is a common requirement. Using OpenNMS to monitor websites can be done by using the built in HTTP/HTTPS based monitors.

While a “Node” can be pretty much everything in a network, the internal model to monitor something is pretty old-fashioned and static. Monitoring a service requires to assign a service to an IP address.

This article describes a pattern how you can monitor web sites with low maintenance and without the need to maintain for each website a monitor which is cumbersome in maintenance.