11 Mar

Using Docker Swarm? You gonna love Ansible 2.8!

Ansible 2..8 introduces huge update for Docker Swarm modules

The Ansible is kind of an icon of automation platform. Owned by RedHat but available as a free product on the public license. Developed both by RedHat employees and the community. Docker itself is an icon of containerization. If you use containers you know that automation is the key to simplify management of dockerized infrastructure. In Ansible 2.x many modules covering the docker operations has been introduced, but Docker Swarm was not really covered. However, it is going to change soon! There is a huge update coming with Ansible 2.8 release!

Lately, I started missing some features in Ansible that will allow me to perform some operations on Docker Swarm clusters. And I try to avoid using the command or shell modules as much as possible – running CLI commands on a remote host is like asking for troubles. I decided to fill this gap by myself and as a result, I can say I am now the Ansible community developer, author, and maintainer of a few modules – docker_swarm_facts, docker_node_facts, docker_host_facts, docker_node; and co-author of docker_swarm and the ansible.docker.swarm library.

In next posts, I wanna show you how those modules work. However, if you are looking forward using them I strongly advise you to give them a try now and report any bugs you find so we can fix them before Ansible 2.8 release. You can find them in the devel branch of Ansible repository.

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04 Jan

Observium pollers vertical scaling

Observium in containers

There are several free monitoring tools available for commercial or non-commercial use. I decided to use Observium to monitor my home and remote labs. I had no specific requirements except that it had to have an option to run in Docker containers on RaspberryPi (ARMv6/8 CPUs). The downside of all monitoring solutions are the resource requirements. There are three resources that matter – storage, memory, and CPUs. Vertical scaling of Observium pollers and other processes is one of the solutions if your hardware resources are limited.

The vertical scaling means adding more workers doing the same process in parallel, but tasks assigned to each process should not overlap. In my case, I wanted to spread the polling across my RaspberryPi cluster. Polling process can consume the CPU and make RaspberriPi unresponsible. In worst scenario, if you have many devices or you are poling lots of data from your devices the polling processes may not finish their work within 5 minutes (this is how often devices have to be queried) so you will miss some data. You may of course tune number of threads the polling process start but any platform has it resources limitations you cannot bypass.  

In this article I will present my solution based on Docker Swarm cluster. It has some limitations and downsides but may work for many people, not only on RaspberyPi.

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