Intro to Docker

Introduction to Docker

https://ubc-library-rc.github.io/intro-docker/

Land Acknowledgement

UBC Vancouver is located on the traditional, ancestral, and unceded territory of the xʷməθkʷəy̓əm (Musqueam) peoples.

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I have never used virtual machines or virtual environments.

I use virtual machines, virtual environments, and containers in my workflow

Learning Objectives

Have an understanding of computational environments and Docker containers
Identify Docker use cases and explain common terminology
Use existing Docker containers for common tasks
Get familiar with the process of building your own containers

Pre-workshop setup

Optional: Set up Docker on your system

For more information, check out Docker Installation

What is Docker?

Some Definitions

Apps
Operating System\Kernel
Process
Instance
Library
Virtualization

the word “app” is widely used to mean many things, but overall it is any program or group of programs targeted towards computer end users, A running version of a program or application is called an instance. When you download and install a piece of software, your local copy is an instance of that program. It might be different from another instance as it has its own configurations and data files. Programs and tools need resources to execute our commands and some common ones are stored in units called libraries. It is reasonably parallel to an actual library. Libraries and application parameters or Settings create an environment. one of the applications on your machine is a computer operating system which manages the computing hardware and provides a platform for user-facing applications and services Within operating system has a central program that controls the other programs and is called the Kernel. Kernel is an interface between hardware and software.

From Wikimedia

the word “app” is widely used to mean many things, but overall it is any program or group of programs targeted towards computer end users, one of those applications is a computer operating system which manages the computing hardware and provides a platform for user-facing applications and services Within operating system has a central program that controls the other programs and is called the Kernel. Kernel also manages hardware. Each kernel has its own interface, that is why we cannot run windows applications on Linux. Under the hood, the applications are constantly talking to the kernel. Some software capabilites are closely tied to hardware. Virtualization uses software to create a virtual representation of the hardware. When you install a virtual machine on your system, it behaves like an independent computer, even though it is running on just a portion of the actual underlying computer hardware. Virtualization enables more efficient utilization of physical computer hardware and is the foundation of cloud computing.

Then, what are containers?

From Netapp

Benefits of Virtualization

Using resources efficiently
Easier management of resources
Minimal downtime

- Before virtualization, each application server required its own dedicated physical CPU.Invariably, each physical server would be underused. In contrast, server virtualization lets you run several applications—each on its own VM with its own OS—on a single physical computer - Replacing physical computers with software-defined VMs makes it easier to use and manage policies written in software. This means that you can build perfectly replicated machines and install applications repeatedly and consistently without cumbersome, time-consuming. and error-prone manual setup. - With Virtual Machines, you can run even run redundant environments to minimize downtime. Virtual machines were first developed in the 1960s, to enable “time sharing” of computing hardware resources for multiple simultaneous users. The real computer which the VM is running on is often called the host, and the software running on it which creates virtual machines is called a hypervisor.

More Terms and Definitions

Resource allocation
Isolation
Layering

We want to talk about a few use cases of Docker in the next section, but before that, lets talk about a few broader principles that apply to both virtual machines and containers: Processes on your system are working alongside each other. Cloud servers handle lots of processes in miliseconds, but How do we ensure computing processes have access to the resources they need? Resource allocation is very important in that regard When processes are running on the same kernel, how do we protect our computing environments from security risks when introducing new computer processes, as well as protecting them from the negative impact of bugs? By running processes in isolation, we can minimize their impact on each other. Also, by layering processes and give special permissions to each layer, permissions are restricted to lower-level systems layers, preventing containerized processes from touching the operating system. That is why containers are good choices for sandbox projects

Benfits of containers?

Lightweight but less fault tolerant
Lower overhead
Less security

Docker's impact

things just work
no more struggling with dependencies
enables reproducible computing

Generally, there are three reasons for processes not running properly on our system: 1. One or more files Missing 2. the libraries and other dependencies does not match the version installed on the machine 3. environment variables are different between machines Docker keeps the process of interacting with applications consistent and as all libraries, packages, and dependencies should be included with the Docker blueprint, so the piece of software will work right out of the box for its recipient and finally when sharing software, research, or other data, you can provide a Docker image to ensure your recipients do not have to scramble to duplicate the development environment in which it can work most optimally. Additionally, when others create containers from your Docker image, any actions they take within that container will not alter the original Docker image for others.

From knoldus

Paths to Installing Docker

Docker Engine is available through Docker Desktop.

Docker Hub's Playground

https://labs.play-with-docker.com/

A simple activity

From DEV

To start our activity, we need to know a little bit more about Docker workflow: The instructions for making a Docker Container is contained in a Docker image. Docker-images are templates used to build containers. Images also contain metadata that describe the containers capabilities and needs. By running docker build, the docker daemon creates an image based on the instructions in the Dockerfile. By running docker build, docker daemon uses the image to make an instance of the environment. We can make as many instances of an image as we want. docker version docker run hello-world docker image pull ubuntu docker image ls docker container run alpine ls -l docker container run ubuntu echo "hello from ubuntu" docker container run -it alpine /bin/sh docker image docker build typically we start with a base image

Docker Hub

Dockerfile

Resources and next steps

Key Takeaways

Any software depends on other software pieces to function, but each component evolves in its own time frame.
Docker containers are small environments that contain the components needed for a given task
Containers are easy to maintain, reproducible, and allow efficient management of hardware resources.
Containers are built from a set of instructions and Docker is only one tool for building containers.