Dev At Rest

Containers Kernel, namespace, cgroups

Kernel space and user space

Before we actually get to explain containers let's define what is a kernel.  Because you know there is no such thing in reality as a kernel it's only how we name things, and different people name things differently.

cgroups, namespaces, UFS

We are going to discuss containers, cgroups, namespace, UFS, hypervisor, user space, kernetl space and more.

When we say "kernel" we mean this.  We have the hardware, this is not the kernel, now above the hardware we have a few layers of software, imagine now two boxes.

Introduction

When you run an SQL Query you select rows, but what if you want to have a summary per multiple rows, for example you want to get the top basketball for each country, in this case we don't only group by country, but we want also to get the top player for each of the country.  This means we want to group by country and then select the first player.