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Presentation notes from JMU Unix Users Group meetings

Ripley’s Thoughts on Containerization

Just a random collection of ideas to set the tone for the next few weeks


What is the right size of a computer?


Bare Metal Servers

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Virtual Machines

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Containers

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A brief aside with some caveats


Beware of posting slides for review early as it can attract trolls


A study of containerization shouldn’t be limited to Linux


https://lwn.net/Articles/780364/


Linux containers don’t really “exist”


What are namespaces?


What namespaces are there?


cgroups

You can use cgroups today inside systemd unit files to help control uncooperative services.


Enter Docker


Redhat’s docker Concerns


Docker vs docker vs containers


How is a container built? Dockerfile


How is a container built? Filesystem layers


Dockerfile worst case scenario

FROM ubuntu:18.04

COPY index.html /var/www/html # frequent changes here invalidate layers

RUN apt-get update # huge download creates layer
RUN apt-get install -y apache2
RUN apt-get clean # create a huge negative layer

EXPOSE 80

CMD ["/usr/sbin/apache2", "-D", "FOREGROUND"]

Dockerfile better example

FROM ubuntu:18.04

# Only preserve the Apache package
RUN apt-get update && apt-get install -y apache2 && apt-get clean

# Keep the most volatile layer at the end
COPY index.html /var/www/html

EXPOSE 80

CMD ["/usr/sbin/apache2", "-D", "FOREGROUND"]

Kubernetes

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Kubernetes Components


Kubernetes Objects


Kubernetes Distros


The End