Unpacking the Container: A Crash Course in Virtualized Container Technology

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Unpacking the Container A Crash Course in Virtualized Container Technology Melissa McKay http://jfrog.com/shownotes

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MELISSA MCKAY Developer Advocate @JFrog melissajmckay

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HOW ARE YOU USING CONTAINERS TODAY??? • LOCALLY • TEST/QA ENVIRONMENTS • PRODUCTION • WE DON’T USE THEM TODAY • WE ARE CONSIDERING USING THEM

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THE AGENDA • Brief History • The Container Market • What is Docker? • What is a Container? • Container Gotchas

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ALL ABOUT … CONTAINERS

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SHARING LIMITED RESOURCES 1979 / 1982- chroot

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PROGRESS TOWARD VIRTUALIZATION ▪ 2000 - FreeBSD jail ▪ 2004 - Solaris Zones / snapshots ▪ 2006 - Google Process Containers / cgroups ▪ 2008 - IBM LinuX Containers (LXC) ▪ 2013 - Docker (open source!) - Google LMCTFY (open source!) ▪ 2014 - Docker trades LXC for libcontainer ▪ … more stuff happened ▪ June 2015 - Open Container Project/Initiative (OCI) ○ Runtime Specification (runtime-spec) ○ Image Specification (image-spec) ▪ … even more stuff happened and is still happening!

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THE CONTAINER MARKET (according to Sysdig) 2017 - 45,000 Containers, 99% Docker 2018 - 90,000 Containers Fig. 1. 2018 Container Runtimes from: “2018 Docker usage report,” 29 May. 2018, sysdig.com/blog/2018-docker-usage-report/. Accessed 10 Jun. 2020. 10

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THE CONTAINER MARKET 2019 - 2 million Containers (includes both SaaS & on prem users) Fig. 2. 2019 Container Runtimes from: “Sysdig 2019 Container Usage Report: New Kubernetes and security insights,” 29 Oct. 2019, sysdig.com/blog/sysdig-2019-container-usage-report/. Accessed 10 Jun. 2020. 11

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WHAT EXACTLY IS DOCKER? 12

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WHAT DO WE ACTUALLY NEED/WANT? • An isolated environment where a user/application can operate, sharing the host system’s OS/kernel without interfering with the operation of another isolated environment on the same system (a container) • A way to define a container (an image format) • A way to build an image of a container • A way to manage container images • A way to distribute/share container images • A way to create a container environment • A way to launch/run a container (a container runtime) • A way to manage the lifecycle of container instances 13

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DOCKER, THE WHOLE PACKAGE docker images DOCKER ENGINE DOCKER IMAGE FORMAT Dockerfile docker build docker rm docker push docker pull DOCKER HUB docker run docker stop docker ps 14

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BREAKING UP THE MONOLITH OCI IMAGE FORMAT • Docker V2 Image Spec OCI CONTAINER RUNTIME • runC (which used to be libcontainer… which was written by Docker) OTHERS - containerd, rkt, cri-o, Kata, etc… https://lwn.net/Articles/741897/ https://www.ianlewis.org/en/container-runtimes-part-1-introduction-container-r 15

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WHAT IF I DON’T WANNA DOCKAH?? & Skopeo https://developers.redhat.com/blog/2019/02/21/podman-and-buildah-for-docker-users/ https://www.redhat.com/en/blog/say-hello-buildah-podman-and-skopeo https://developers.redhat.com/blog/2020/02/12/podman-for-macos-sort-of/ 16

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WHAT EXACTLY IS A CONTAINER? 17

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CONTAINER COMPONENTS TARBALL OF A FILESYSTEM LINUX FEATURES • namespaces • cgroups • Union File systems Mix these together to create and run a container! Voila! https://docs.docker.com/get-started/overview/ 18

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FILESYSTEM DETAILS … … NOTE: On OSX, containers will actually be running in a tiny Linux VM (use screen) screen ~/Library/Containers/com.docker.docker/Data/vms/0/tty screen ~/Library/Containers/com.docker.docker/Data/vms/0/tty 19