Build OpenNMS with Docker

Being able to compiling an open-source project is important. You can change the code, so you should also able to build it.

Why is there a dedicated Docker image for the build environment? The dependencies running a pre-build OpenNMS Horizon distribution and compiling from source are different. To build OpenNMS Horizon you need Apache Maven and to compile JICMP, JRRD you need a C compiler environment. This is nothing you want to carry when you just want to run OpenNMS Horizon.

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. It helped to make development workflows transparent for everyone. The interface was quick, simple, well accepted and it was not plastered with popups and advertisements. It was started in 2007 by the company GitHub, Inc. in San Francisco. In a very short amount of time it was so well accepted, it killed SourceForge and Google Code. It was the prototype of “disrupting” the way how people collaborate in software development, especially in open-source projects.

Scanning for SNMP communities

Adding devices into monitoring system is easy. Getting all the right SNMP communities for them is harder. People don’t give you the right community string or forget to open firewall ports.

If you have to test a lot of IP’s against various IP addresses you can use nmap and a community list file as an input.

Be aware you talk about permission to run this test otherwise somebody can get angry when you try to brute-force community strings against their devices.

Centralized Logging with Graylog2

How many times do you connect with SSH to your remote server and cat, grep, tail and awk through your logs? It probably works for 3 servers and running a handful services, but if you have more, you should definitely spend some time to centralize your logs.

I personally prefer Graylog2 which can deal very well with different log formats like GELF, Syslog RFC’s. Just start some listener with the format and forward them to your Graylog2 instance.

Cleaner log with Docker and SNMP

Centralizing logs is important as soon you have more than 2 servers. In my environment the bare metal is monitored with Net-SNMP and my services are deployed as containers with Docker. All system logs are sent to a Graylog2 instance and I quickly noticed a few ugly entries caused by snmpd.

Cannot statfs /run/docker/netns/...: Permission denied

You will notice a few of them. First approach try to increase the logging level in /etc/default/snmpd from SNMP daemon with

Monitoring DevOps and the Status Quo

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. Great user experience, functionality and a good “Effort-to-Outcome” ratio to solve your problems will make your software successful.

Docker Shell Corner Cases

During work building Docker executables, I ran in an interesting corner case. Fortunately the Docker IRC channel helped me to investigate with special credits to Ravensoul.

When you build a container as an executable you can use the ENTRYPOINT for your binary to execute and CMD as a default overwritable argument. In most cases the CMD is the --help argument to provide a useful default behavior in case you just run the container without anything specified.

Mac OS X and DHCP is screwing your Host Name

I’m using Mac OS X with iterm2, oh-my-zsh and spend 75% of my time in those terminals. It is totally annoying to me if I connect to a DHCP network and it screws up my hostname. Especially when I’m used to looking at the prompt which tells me the host I’m connected to.

It is possible to fix your computer name for several things using the scutil command which requires administration permissions. I’ve found a link to the Mac OS X Server Worksheet which explains a few things in more detail. Here is what I did to prevent my computer changing the host name.

Zyxel vs. Vodafone Easybox with VDSL 50

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.