Kubernetes Architecture

So what are Containers ?

Before going to containers, lets understand VM’s and history:

• create the new image

• Docker Commit: Creates an image from a container.
•  Docker Export: Creates a tar file from a container.
• Docker import: Creates a image from a tar file.

Docker Network:

• Till now we have seen docker is getting ip addresses right, from where is it getting ip address??
• Docker’s networking subsystem is pluggable. ie., it is like a plugin we will not be implementing as part of the
• Containerd
• Shrim
• Runc

Dockerd:

• Listem for Docker Engine API Requests

Containerd:

• Introduced in Docker 1.11
• Responsibility of managing container life cycle
• Containerd is the executor for containers
• Executing containers by calling RUNC with the right parameters to run containers.

Runc:

• Container used runc to do all the linux work by interacting with the kernel
• By interacting with the kernel, it creates the container process and another process called as containerd-shim
• Once the container starts, the runc get exists

Containerd-shim:

• It allows you to run daemon less containers
• When the container process dies, containerd-shim will inform the status to containerd and exists

Docker Images:

• A Docker Image is a file, used to execute code in a container.
• It’s a Read only Template.
  1. The containers are not so self-sufficient to host the application, and to work on a highly scalable application, so that’s the reason people started looking toward an options like orchestration tool (Ex: Kubernetes)