contai-nerd

To get a fully understanding about kubernetes we need to first understand what is behind Docker and POD concept. I'll try to summarize some of the important concept because in internet you can find more detailed articles! Many of you heard about docker first and after containers, but the core thing is container concept not Docker and the next question is why we need another abstraction like POD?!?!? Let's talk about containers! Container is concept introduced in linux kernel long time ago and it's not a primitive but a term to describe the combination of two important feature of the linux kernel: cgroups namespaces cgroups and namespace are first class object used to create an isolated process with its own view of the host resources such as, network and disk and limit host resource usage for example how much memory this process can manage. To create a container without the help of docker we can use the syscall " unshare " : unshare --fork --pid -

In this blog series I would explain some core concept about kubernetes to understand better how is life saver ICP for an IT department that facing for the first time this new technologies. In this post I explain how it works a plain kubernetes architecture. Kubernetes has two main components master and worker node. Master is the main component, and is responsible in managing worker nodes state. Worker node is responsible to mantain all the PODS ( and not a simple docker image but will cover better on the next post POD concept ) up and running. Before to go deeper inside the architecture it's important to understand these two components. Master node has internally four important components: REST API Server to manage kubernetes and pod state( kube-apiserver) Scheduler watching for new pod to assign on node (kube-scheduler) Controller Manager is a complex concept, in short terms is responsibile about the cluster management and evolution state a full description is here