A presentation at GIDS.CLOUD Live by Melissa McKay
UNPACKING THE CONTAINER A Deep Dive into Virtual Container Technology Melissa McKay @melissajmckay http://jfrog.com/shownotes
MELISSA MCKAY Developer Advocate @JFrog @melissajmckay 5
THE AGENDA • Brief History • The Container Market • What is Docker? • What is a Container? • A few Container Gotchas • Managing Images with JFrog Artifactory 6
ALL ABOUT … CONTAINERS 7
SHARING LIMITED RESOURCES 1979 / 1982- chroot 8
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! 9
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
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
WHAT EXACTLY IS DOCKER? 12
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
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
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
WHAT EXACTLY IS A CONTAINER? 16
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/ 17
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 18
FILESYSTEM DETAILS … … 19
FILESYSTEM DETAILS 20
A FEW CONTAINER GOTCHAS 21
CONTAINER GOTCHAS - RUNNING AS ROOT 22
CONTAINER GOTCHAS - NO CONSTRAINTS 23
CONTAINER GOTCHAS - NEVER UPDATING 24
MANAGING YOUR IMAGES - ARTIFACTORY 25
MANAGING YOUR IMAGES - XRAY 26
THANK YOU! Melissa McKay @melissajmckay http://jfrog.com/shownotes
Containers have become integral to every phase in the lifecycle of application development. Production grade orchestration tools such as Kubernetes have been built to manage them and container platforms like Docker are becoming commonplace in both testing and development. Web tutorials on how to build and manage simple Docker images abound! But what are containers exactly and why have they become so essential to the DevOps ecosystem? This talk is for those curious minds who want to look below the surface and really understand the mechanics of a technique that has actually been around longer than you may think. Where did Docker come from?
What about other projects in the container ecosystem - are there alternatives? What does a Docker image actually look like on the filesystem? How do Docker image layers work? What are cgroups? How are system resources allocated and managed and are there any gotchas that you should be aware of? What about security? How can JFrog Container Registry help me manage my Docker images? After this talk, you will have a solid understanding of the what, how & why of virtualized container technology.
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