Better way to learn containers

A better way to learn containers

Disclaimer

Container = OCI compliant container (e.g Docker container).

What a container is not ?!

Containers vs VMs: the bad analogy

Docker vs VMs

Wrong again

Containers are running on/by the kernel (not on the CE)

Linux Kernel Containers

Confusions

How to SSH into a container ?
How to execute more than one CMD per container ?
How come the container exits after docker run <img> ?

How to provision (Ansible, Chef …) my docker container ?
Why shouldn’t I install my deps directly in the container using docker exec -it \<container\> apt install \<pkg\> Instead of using images and Dockerfiles ?
…

What is a container ?!

Containers are nothing but “special” linux processes

Linux technologies
- Namespaces (PID, UID, MOUNT, NET …)
- Chroot
- Cgroups
- SELinux, AppArmor
- Capabilities
- SECCOMP
“Linux containers” is not a real thing !!

Why are containers compared to VMs ? (OS virtualization Era)

Containers history

Running containers

Container lifecycle

Running Containers

Case study: Docker

Docker runtime

Case Study: PBS (container-tools)

PBS

System container runtimes: LXC/LXD, OpenVZ …

PBS

Thank you

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A better way to learn containers