Docker and Kubernetes
Feb 2024, Ulf Schneider
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Docker Containers
Docker allows to package software applications into images
The image
The image has everything the application needs to run
code, runtime, libraries, settings, ...
The image can be uploaded to a registry (public and private) for reuse, e.g. hub.docker.com
The image can easily be shared and distributed across platforms (Linux, Win, Mac)
A running instance of an image is a container
Run a web server with a Docker tutorial
docker run --rm -p 4230:80 docker/getting-started- Point your browser to http://localhost:4230/
Multiple containers can be started from a single image
Containers run on different platforms because of virtualization
Virtualization allows a single computer to be divided into multiple virtual computers
What is the difference of a container and a virtual machine?
Docker containers use the hosts operating system
Virtual machines bring their own operating system
Containers reuse the OS Kernel
Compared to a VM, a Docker container
- needs much less cpu and memory
- is smaller in size (mb vs. gb)
- will startup much faster (sec vs. min)
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Kubernetes
Kubernetes is a management layer to orchestrate many containers (100s and 1000s)
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You might as well read and write K8s instead of Kubernetes
How Kubernetes and Containers play together
Kubernetes provides for containerized services
- high availability
- scalability
- disaster recovery
A container inside of Kubernetes is a pod
Kubernetes cluster architecture sketch
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Have fun with containers!
Docker and Kubernetes Feb 2024, Ulf Schneider