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0x09-web_infrastructure_design

README.md

0x09. Web infrastructure design

DevOps SysAdmin web infrastructure

https://youtu.be/lQNEW76KdYg

Resources

Read or watch:

Requirements

General

  • A README.md file, at the root of the folder of the project, is mandatory
  • For each task, once you are done whiteboarding (on a whiteboard, piece of paper or software or your choice), take a picture/screenshot of your diagram
  • This project will be manually reviewed:
  • As each task is completed, the name of that task will turn green
  • Upload a screenshot, showing that you completed the required levels, to any image hosting service (I personally use imgur but feel free to use anything you want).
  • For the following tasks, insert the link from of your screenshot into the answer file
  • After pushing your answer file to GitHub, insert the GitHub file link into the URL box
  • You will also have to whiteboard each task in front of a mentor, staff or student - no computer or notes will be allowed during the whiteboarding session
  • Focus on what you are being asked:
  • Cover what the requirements mention, we will explore details in a later project
  • Keep in mind that you will have 30 minutes to perform the exercise, you will get points for what is asked in requirements
  • Similarly in a job interview, you should answer what the interviewer asked for, be careful about being too verbose - always ask the interviewer if going into details is necessary - speaking too much can play against you
  • In this project, again, avoid going in details if not asked

Tasks

0. Simple web stack

A lot of websites are powered by simple web infrastructure, a lot of time it is composed of a single server with a LAMP stack.

On a whiteboard, design a one server web infrastructure that hosts the website that is reachable via www.foobar.com. Start your explanation by having a user wanting to access your website.

Requirements:

  • You must use:
    • 1 server
    • 1 web server (Nginx)
    • 1 application server
    • 1 application files (your code base)
    • 1 database (MySQL)
    • 1 domain name foobar.com configured with a www record that points to your server IP 8.8.8.8
  • You must be able to explain some specifics about this infrastructure:
    • What is a server
    • What is the role of the domain name
    • What type of DNS record www is in www.foobar.com
    • What is the role of the web server
    • What is the role of the application server
    • What is the role of the database
    • What is the server using to communicate with the computer of the user requesting the website
  • You must be able to explain what the issues are with this infrastructure:
    • SPOF
    • Downtime when maintenance needed (like deploying new code web server needs to be restarted)
    • Cannot scale if too much incoming traffic

Please, remember that everything must be written in English to further your technical ability in a variety of settings.

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1. Distributed web infrastructure

On a whiteboard, design a three server web infrastructure that hosts the website www.foobar.com.

Requirements:

  • You must add:
    • 2 servers
    • 1 web server (Nginx)
    • 1 application server
    • 1 load-balancer (HAproxy)
    • 1 set of application files (your code base)
    • 1 database (MySQL)
  • You must be able to explain some specifics about this infrastructure:
    • For every additional element, why you are adding it
    • What distribution algorithm your load balancer is configured with and how it works
    • Is your load-balancer enabling an Active-Active or Active-Passive setup, explain the difference between both
    • How a database Primary-Replica (Master-Slave) cluster works
    • What is the difference between the Primary node and the Replica node in regard to the application
  • You must be able to explain what the issues are with this infrastructure:
    • Where are SPOF
    • Security issues (no firewall, no HTTPS)
    • No monitoring

Please, remember that everything must be written in English to further your technical ability in a variety of settings.

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2. Secured and monitored web infrastructure

On a whiteboard, design a three server web infrastructure that hosts the website www.foobar.com, it must be secured, serve encrypted traffic, and be monitored.

Requirements:

  • You must add:
    • 3 firewalls
    • 1 SSL certificate to serve www.foobar.com over HTTPS
    • 3 monitoring clients (data collector for Sumologic or other monitoring services)
  • You must be able to explain some specifics about this infrastructure:
    • For every additional element, why you are adding it
    • What are firewalls for
    • Why is the traffic served over HTTPS
    • What monitoring is used for
    • How the monitoring tool is collecting data
    • Explain what to do if you want to monitor your web server QPS
  • You must be able to explain what the issues are with this infrastructure:
    • Why terminating SSL at the load balancer level is an issue
    • Why having only one MySQL server capable of accepting writes is an issue
    • Why having servers with all the same components (database, web server and application server) might be a problem

Please, remember that everything must be written in English to further your technical ability in a variety of settings.

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3. Scale up

Readme

Requirements:

  • You must add:
    • 1 server
    • 1 load-balancer (HAproxy) configured as cluster with the other one
    • Split components (web server, application server, database) with their own server
  • You must be able to explain some specifics about this infrastructure:
    • For every additional element, why you are adding it

Please, remember that everything must be written in English to further your technical ability in a variety of settings.

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