mattogodoy/omni repository overview

⁠OMNI

A very lightweight monitoring system for Raspberry Pi clusters running Kubernetes.

⁠Why?

When I finished my Kubernetes cluster using a few Raspberry Pis, the first thing I wanted to do is install Prometheus + Grafana for monitoring, and so I did. But when I had all of it working I found a few drawbacks:

• The Prometheus exporter pods use a lot of RAM
• The Prometheus exporter pods use a considerable amount of CPU
• Prometheus gathers way too much data that I don't really need.
• The node where the main Prometheus pod is installed gets all of the information and saves it in its own database, constantly performing a lot of writes to the SD card. SD cards under lots of constant writing operations tend to die.

Last but not least, I like to learn how these things work.

⁠Advantages

Omni has (what I consider) some advantages over the regular Prometheus + Grafana combo:

• It uses almost no RAM (13 Mb)
• It uses almost no CPU (between 2m and 6m)
• It gathers only the information I need
• All of the information is sent to an InfluxDB instance that could be inside or outside the cluster. This means that no information is persisted in the disk, extending the SD cards lifetime.
• InfluxDB acts as the database and the graph dashboard at the same time, so there is no need to also install Grafana (although you could if you wanted to).

⁠Prerequisites

For Omni to work, you need to have the libseccomp2.deb library installed in each of your nodes to avoid a Python error:

Fatal Python Error: pyinit_main: can't initialize time

(more info here⁠)

To install it you can do it in two ways (only one is needed):

• Ansible: all nodes at the same time

  Edit the file ansible-playbook-libs.yaml in this repo, add your hosts and run:

  ansible-playbook install-libs.yaml
  

  Copy

• SSH: one by one

  Connect into each of your nodes and run:

  wget http://ftp.us.debian.org/debian/pool/main/libs/libseccomp/libseccomp2_2.5.1-1_armhf.deb
  sudo dpkg -i libseccomp2_2.5.1-1_armhf.deb
  

  Copy

Once you have it, everything should work ok.

⁠Setup

Before deploying you'll have to specify the attributes of your InfluxDB instance.

1. Copy the configuration template file to the one you'll deploy:

   cp omni-config-example.yaml omni-config.yaml
   

   Copy

2. Open omni-config.yaml and fill the variables with your InfluxDB instance information.

   NOTE: The attribute OMNI_DATA_RATE_SECONDS specifies the number of seconds that pass between data reporting events that are sent to the InfluxDB server.

3. Deploy the configuration for Omni to work:

   kubectl apply -f omni-config.yaml
   

   Copy

4. Check that the configuration were created correctly:

   kubectl describe configmap omni-config
   

   Copy

   You should see the configuration values.

⁠Installation

Once the configuration is done, all that is left is to deploy the DaemonSet of Omni pods:

kubectl apply -f omni-daemonset.yaml

Check that everything is running as expected:

kubectl get pods

And you are done! 🎉

⁠Contributions

Pull requests with improvements and new features are more than welcome.