Using Travis CI to test Docker builds

In last months article we discussed “Dockerizing” this blog. What I left out from that article was how I also used Docker Hub's automatic builds functionality to automatically create a new image every time changes are made to the GitHub Repository which contains the source for this blog. The automatic builds are useful because I can simply make changes to the code or articles within the repository and once pushed, those changes trigger Docker Hub to build an image using the Dockerfile we created in the previous article....

 · 13 min · Benjamin Cane

Getting started with Docker by Dockerizing this Blog

Docker is an interesting technology that over the past 2 years has gone from an idea, to being used by organizations all over the world to deploy applications. In today's article I am going to cover how to get started with Docker by “Dockerizing” an existing application. The application in question is actually this very blog! What is Docker Before we dive into learning the basics of Docker let's first understand what Docker is and why it is so popular....

 · 20 min · Benjamin Cane

Preventing duplicate cron job executions

I feel like sometimes cron jobs create more problems than they solve. It's not the fault of cron, but rather the jobs being executed. This is especially true when the jobs result in duplicate running instances like the following example. $ ps -elf | grep forever 4 S vagrant 4095 4094 0 80 0 - 1111 wait 21:59 ? 00:00:00 /bin/sh -c /var/tmp/forever.sh 0 S vagrant 4096 4095 0 80 0 - 2779 wait 21:59 ?...

 · 13 min · Benjamin Cane

Building Self-Healing Applications with Saltstack

Self healing infrastructure is something that has always piqued my interested. The first iteration of self healing infrastructure that I came across was the Solaris Service Management Facility aka “SMF”. SMF would restart services if they crashed due to hardware errors or general errors outside of the service itself. For today's article we are going to explore another way of creating a self healing environment; going beyond restarting failed services. In today's article we are going to take a snippet of code that connects to a database service and give that application not only the ability to reconnect during database failure but also give it the ability to automatically resolve the database issues....

 · 11 min · Benjamin Cane

A Quick and Practical Reference for tcpdump

When it comes to tcpdump most admins fall into two categories; they either know tcpdump and all of its flags like the back of their hand, or they kind of know it but need to use a reference for anything outside of the basic usage. The reason for this is because tcpdump is a pretty advanced command and it is pretty easy to get into the depths of how networking works when using it....

 · 26 min · Benjamin Cane