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0x0F-load_balancer

README.md

0x0F. Load balancer

DevOps SysAdmin

qfdked8

Background Context

You have been given 2 additional servers:

  • gc-[STUDENT_ID]-web-02-XXXXXXXXXX
  • gc-[STUDENT_ID]-lb-01-XXXXXXXXXX

Let’s improve our web stack so that there is redundancy for our web servers. This will allow us to be able to accept more traffic by doubling the number of web servers, and to make our infrastructure more reliable. If one web server fails, we will still have a second one to handle requests.

For this project, you will need to write Bash scripts to automate your work. All scripts must be designed to configure a brand new Ubuntu server to match the task requirements.

Resources

Read or watch:

Requirements

General

  • Allowed editors: vi, vim, emacs
  • All your files will be interpreted on Ubuntu 16.04 LTS
  • All your files should end with a new line
  • A README.md file, at the root of the folder of the project, is mandatory
  • All your Bash script files must be executable
  • Your Bash script must pass Shellcheck (version 0.3.7) without any error
  • The first line of all your Bash scripts should be exactly #!/usr/bin/env bash
  • The second line of all your Bash scripts should be a comment explaining what is the script doing

Tasks

0. Double the number of webservers

In this first task you need to configure web-02 to be identical to web-01. Fortunately, you built a Bash script during your web server project, and they’ll now come in handy to easily configure web-02. Remember, always try to automate your work!

Since we’re placing our web servers behind a load balancer for this project, we want to add a custom Nginx response header. The goal here is to be able to track which web server is answering our HTTP requests, to understand and track the way a load balancer works. More in the coming tasks.

Requirements:

  • Configure Nginx so that its HTTP response contains a custom header (on web-01 and web-02)
    • The name of the custom HTTP header must be X-Served-By
    • The value of the custom HTTP header must be the hostname of the server Nginx is running on
  • Write 0-custom_http_response_header so that it configures a brand new Ubuntu machine to the requirements asked in this task

Example:

sylvain@ubuntu$ curl -sI 34.198.248.145 | grep X-Served-By
X-Served-By: 03-web-01
sylvain@ubuntu$ curl -sI 54.89.38.100 | grep X-Served-By
X-Served-By: 03-web-02
sylvain@ubuntu$

If your server’s hostnames are not properly configured ([STUDENT_ID]-web-01 and [STUDENT_ID]-web-02.), follow this tutorial.

1. Install your load balancer

Install and configure HAproxy on your lb-01 server.

Requirements:

  • Configure HAproxy so that it send traffic to web-01 and web-02
  • Distribute requests using a roundrobin algorithm
  • Make sure that HAproxy can be managed via an init script
  • Make sure that your servers are configured with the right hostnames: [STUDENT_ID]-web-01 and [STUDENT_ID]-web-02. If not, follow this tutorial.
  • For your answer file, write a Bash script that configures a new Ubuntu machine to respect above requirements Example:
sylvain@ubuntu$ curl -Is 54.210.47.110
HTTP/1.1 200 OK
Server: nginx/1.4.6 (Ubuntu)
Date: Mon, 27 Feb 2017 06:12:17 GMT
Content-Type: text/html
Content-Length: 30
Last-Modified: Tue, 21 Feb 2017 07:21:32 GMT
Connection: keep-alive
ETag: "58abea7c-1e"
X-Served-By: 03-web-01
Accept-Ranges: bytes

sylvain@ubuntu$ curl -Is 54.210.47.110
HTTP/1.1 200 OK
Server: nginx/1.4.6 (Ubuntu)
Date: Mon, 27 Feb 2017 06:12:19 GMT
Content-Type: text/html
Content-Length: 612
Last-Modified: Tue, 04 Mar 2014 11:46:45 GMT
Connection: keep-alive
ETag: "5315bd25-264"
X-Served-By: 03-web-02
Accept-Ranges: bytes

sylvain@ubuntu$

2. Add a custom HTTP header with Puppet

Just as in task #0, we’d like you to automate the task of creating a custom HTTP header response, but with Puppet.

  • The name of the custom HTTP header must be X-Served-By
  • The value of the custom HTTP header must be the hostname of the server Nginx is running on
  • Write 2-puppet_custom_http_response_header.pp so that it configures a brand new Ubuntu machine to the requirements asked in this task