Academy PRO: Docker. Lecture 1

Course’s
Agenda
Introduction to Docker
Containerization Basics
Orchestration Basics
Miscellaneous

Today’s
Agenda
What is containers?
Challenges & Solutions
How it works?

What is Docker?
Docker is an open platform that helps companies build, ship and run their
applications everywhere.

Evolution of IT
Earlier
Thick client
Well defined stack
Monolith
infrastructure
Today
Thin client
Many different
services
Running on different
set of resources

Static website
UserDB
API
Web Frontend Queue
Redis + Redis-sentinel
Node.js + Express + Mongoose
MongoDB
Webpack + React + Redux
nginx + bootstrap
Development VM
QA server
Public cluster
Production server
Contributors laptop
Customer datacenter

cgroups - Linux kernel feature that limits, accounts for,
and isolates the resource usage (CPU, memory, disk I/O,
network, etc.) of a collection of processes.
namespaces - feature of the Linux kernel that isolates
and virtualizes system resources of a collection of
processes (pid, mnt, net..)
Linux Containers - operating-system-level virtualization
method for running multiple isolated Linux systems
(containers) on a control host using a single Linux kernel.
LXC combines the kernel's cgroups and support for
isolated namespaces to provide an isolated environment
for applications.

High level approach: lightweight VM
own process space
own network interface
can run stuff as root
can have own sbin/init

Low level approach: chroot on steroids
can also not have its own sbin/init
container = isolated process(es)
share kernel with host
no device emulation

Separation of concerns
Inside:
code
libs
package manager
app
data
Outside:
logging
remote access
network configuration
monitoring

Build once - run everywhere!
Linux containers is units of software development
run everywhere
regardless of kernel version
regardless of host distro
BUT container and host architecture must match
run anything
if you can run it on host - you can run in the container

Virtualization
Advantages:
Multiple OS on same machine
Easy maintenance and recovery
Lower total cost of ownership
Disadvantages:
Multiple VMs Lead to Unstable performance

Containerization
Advantages over virtualization:
Containers on same OS kernel are lighter and
smaller
Better resource utilization
Short boot-up process

Resource/Memory Utilization
16Gb 3Gb
2Gb
1Gb
4Gb
4Gb2Gb
16Gb 3Gb
4Gb
2Gb
VM Containers
7 Gb of Memory blocked and
cannot be used for new VMs

Containerd - industry-standard container runtime
with an emphasis on simplicity, robustness and
portability. It is available as a daemon for Linux and
Windows, which can manage the complete container
lifecycle of its host system: image transfer and
storage, container execution and supervision, low-
level storage and network attachments, etc..
runC - CLI tool for spawning and running
containers according to the OCI (Open Container
Initiative) specification.

What is Docker? #2
Docker is containerization platform which packages your application and all its
dependencies together in the form of containers so as to ensure that your
application works in the same way in any environment be it Development or
Test or Production

Why Docker?
Isolation
Lightweight
Simplicity
Workflow
Community

Official Docker Images
https://hub.docker.com/explore/?page=1

Hello World!
$ docker run hello-world

Academy PRO: Docker. Lecture 1

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Academy PRO: Docker. Lecture 1