Lab 3: Overview

Table of Contents

• Lab 3: Overview

  • Containers

  • Goals for Lab 3

Let’s recap what we have learned over the last two weeks:

1. We explored SaaS products that are self-hosted alternatives to commercial products

   • Rocket.Chat has similar functionality to Slack

   • Nextcloud stores files in the cloud

   • Wordpress is blogging and website building software

2. We configured a VPS to host a webpage using Nginx

   • One server that runs a single web application

3. We configured a packaged product, Rocket.Chat, to run independently on a non-standard port because port 80 was already in use by Nginx

   • One server that runs multiple applications using a pre-configured package

4. We configured Nginx as a reverse-proxy to redirect port 80 traffic to internal ports (3000, for example).

   • The process is transparent to the user of the site.

   • This method allows us to run different applications on the same VPS.

5. We configured two Docker projects.

   • The first Docker project used docker run to pull the image from Docker Hub directly and then run it with minimal configurations. This project was all-inclusive, like Rocket.Chat.

   • The second project had two components (web and database), each running in a different container.

6. Each step is distributing more of the processing power.

   • We have gone from one project per VPS to a self-contained package installer that runs in isolation to a project that runs different components separately.

Containers

Physical space in data centers and the processing power of the hardware is finite, but resources go unused. One way to maximize resources is to virtualize the technology to use the same hardware. Instead of running one operating system (OS) per server, each server could run a base operating system with many virtualized OSs, with each virtual OS having n number of microservices or larger systems running in their own virtualized OS.

We will focus on containers, which visualize the OS instead of virtualizing the underlying hardware as a virtual machine does. Containers are lightweight and have a small footprint. They can start up very quickly. Linux distributions, such as Alpine Linux, are built for containers. Alpine Linux has a base footprint of just 5MB, whereas Ubuntu and CentOS are around 180MB. The hello world Docker image that ran last week has a size of 1.84kB! Run docker images to view the size of the images on your VPS.

Resources

• What are the levels of virtualization?

• What’s the Diff: VMs vs Containers

• What are microservices?

• Docker Tutorial: Containers, VMs, and Docker for Beginners

Goals for Lab 3

We will explore how to containerize applications so that we can run a service using multiple smaller containers.

During this lab, you will:

1. You will assemble two web applications using different containers to decentralize the project using Docker Compose.

   • Wordpress

   • Nextcloud

2. You will learn how to separate the data from the web application.

3. You will configure a memory caching service, which is a core technology to cloud and distributed computing.