Module 6: Virtualization and Containerization

Where do docker images come from?

- An image is essentially built from the instructions - Docker pull which is run automatically by docker run

"Pet servers"

- Few of them - Are given names like mail.mycompany.com - Are built to solve the task at hand (email) - When they are "sick" we "nurse them back to health" -Cant automate them because there is something unique about them

"Cattle servers"

- Lots of them - Are given names like s0045.mycompany.com - Are built to do the same thing: compute and storage - When they are "sick" we "take them out of commission" and replace with another. "Treat Servers like Cattle, Not Pets"

What is state? What is irreproducible state?

- State: How your application currently runs - Irreproducible state: Something you can't reproduce --> Configured it in a way where you can't quickly edit it

Infrastructure as Code Methodology

- Treat your infrastructure as if it were code! (automate everything!) - Store configurations, dependencies and scripts to bootstrap your systems in a source code management (SCM) system like Git. - This allows you set-up and tear down environments quickly and easily and deploy your systems in Dev, Test or Production. - Servers are commodity / utility resources, and not at all strategic. -"Build reproducible infrastructure or things you can replace ‐‐> automates tasks" - "Managing and provisioning computer data centers through machine-readable definition files, rather than physical hardware configuration or interactive configuration tools."

How does Virtualization differ from Containerization?

- Virtualization of server vs virtualization of the service/application - Containerization focuses on trying to virtualize the service independent of the server itself (independent of the OS)

Write a docker command to run the command echo "hi" on the image ubuntu.

> docker run ‐ti ubuntu:latest echo "hi""

What are the two ways you can network containers in docker?

Bridge: network used by containers that don't specify a preference to be pout in any other network Host: used when you want a container to not have any network isolation at all. --> Has security concerns

The term referring to computers that do not store their state and therefore are replaceable is.... Pets Cattle Hosts Guests

Cattle

Essential Components of any System

Code - The functionality (Input) Data - The inputs and outputs to that system (output) Infrastructure - The Software required to run the code and store the data

A _____ system is what your virtual machines will run on and has the primary and first installed Operating System. Host Guest Container Image

Host

In containerization technology, a(n) ________ holds the software, dependencies and information necessary to run an application. Image Container Volume Registry

Image

Which of the following could be a potential downside to running Infrastructure as Code? Increase in costs Increase in technical skills needed Increase in risks to infrastructure Increased risk of failure

Increase in costs

What are the two types of docker volumes?

Persistent: Data places here will be available on the host, even when the container goes away Ephemeral: Data placed here will be available on the host as long as the container is using them; when no container is using them, they evaporate --> They'll stick around as long as they're being used, but they're not permanent.

Which of the following is a potential benefit to running Infrastacture as Code? Increase in costs Reduction of risks Increase in complexity Reduce speed for deployments

Reduction of risks

Containerization

a form of operating system virtualization, through which applications are run in isolated user spaces called containers, all using the same shared operating system (OS) - Creates container for the app --> Takes all the pieces of the application that are needed to run it and takes just those pieces - Does not worry about the operating system - Not easy

Container

a self-contained unit of software based on an image. - "The rules on how the images work together to run an application Images can exist without containers, whereas a container needs to run an image to exist"

How is an image different from a container

containers are dependent on images and use them to construct a run‐time environment and run an application

What docker command turns a container back into an image?

docker commit

How do you inspect the output of a docker container?

docker logs

Which command lists running containers?

docker ps command

What docker command turns an image into a container?

docker run

Virtualization

the act of creating a virtual version of something, including virtual computer hardware platforms, storage devices, and computer network resources - Virtualizes the server

Host

the computer running the virtual machines or containers.

Guest

the operating system running as a virtual machine.

Image

the software necessary to run an application. - A" state of an application (files and resources needed to make an application run) --> pieces of an application"