Presentation 3 - Docker

Test on VMs
Google form with test:

Standardized packaging for software and dependencies
Isolated applications sharing the same OS kernel
Supported on Linux and Windows
What is a container?

Terminology
Docker Image
The basis of a Docker container. Represents a full application
Docker Container
The standard unit in which the application service resides and executes
Docker Engine
Creates, ships and runs Docker containers deployable on a physical or virtual, host locally, in a datacenter or cloud service provider
Registry Service (Docker Hub (Public) or Docker Trusted Registry (Private))
Cloud or server-based storage and distribution service for your images

Docker Image
Examples: Nginx web server, DB server, Nodejs Application
Docker Containers
Each container is created from an image
Images and Containers

Docker containers are NOT VMs
Fundamentally different architectures
Easy to manage
No need to install separate OS
Virtual machine
Containers on one host machine

Docker can work on virtual machines

Using Docker: Build, Ship, Run Workflow
Developers IT Operations
BUILD
Development Environments
SHIP
Create & Store Images
RUN
Deploy, Manage, Scale

Basic Docker Commands
$ docker image pull node:latest
$ docker image ls
$ docker container run –d –p 5000:5000 --name node node:latest
$ docker container ps
$ docker container stop node(or
)
$ docker container rm node (or
)
$ docker image rmi (or
)
$ docker build –t node:2.0 .
$ docker image push node:2.0
$ docker --help

Image can be easily created with dockerfile
Instructions on how to build a Docker image
Looks very similar to “native” commands
Important to optimize your Dockerfile

Each Dockerfile Command Creates a Layer
Kernel
FROM
RUN
WORKDIR
COPY
EXPOSE
…

Docker Volumes – how to avoid data loss?
Volumes mount a directory on the host into the container at a specific location
Can be used to share (and persist) data between containers
Directory persists after the container is deleted
Unless you explicitly delete it
Can be created in a Dockerfile or via CLI

Attaching a container directly to you source code folder
You can mount local source code into a running container
docker container run -v $(pwd):/usr/src/app/ myapp
Improve performance
− As directory structures get complicated traversing the tree can slow system performance
Data persistence
Path to working directory

Other topics to study at home and on practice classes
Networking
How to connect containers on the same host. They will not see one another if network is not configured
Docker compose
How to create a package of several containers.