Lab: Application Deployment (3 Tier)

Introduction

It is common to deploy applications in 3 tiers: presentation, application, and DB. For this exercise presentation will be handled by the browser, application by PHP, and the DB by MariDB.

We will deploy a simple sample application. The application is called trs and is a trivial reservations system used to book meetings with professors.

An instance of the TRS application should be running on csunix. Have a quick look, so you know that the application looks like when it is working. Accounts exist for: james, wayne, alice, and bob. The password is pw for all accouts. TRS on csunix

Here is what we will build today

Part A: Server builds

Configure the base OS on the servers.

db01:
- clone from bookworm_min VM
  - OS: Debian 12
  - Users: root(adminpass) alice(userpass)
- set IP address: 10.1.1.200
- set hostname: db01
- install MariaDB packages: mariadb-server
web01:
- clone from bookworm_min VM
- set IP address: 10.1.1.201
- set hostname: web01
- install packages for php: apache2, php, libapache2-mod-php, php-mysql
- install MariaDB client: mariadb-client
Get the trs application from GitHub
- GitHub project page: https://github.com/profjamesmohawk/trs
- A git refresher (see Part F): Git Lab from Unix Security
- You may use git clone or download a zip file.

Part B: Build the Database

We will need to do a little DBA work as part of the install.

Logon to db01 as root
Tell MariDB to listen for network connections on all interfaces by editing /etc/mysql/mariadb.conf.d/50-server.cnf...
```
bind-address             = 0.0.0.0
```
Verify that you can access Mariad by logging on and running a simply query.
1. Use the mariadb shell to connect as root
```
mariadb
```
2. You should now be in the MariDB command interpreter shell. Your promt should look something like...
```
MariaDB [(none)]>
```
3. Run a tiny query to show the current time
```
select NOW();
```
4. Exit the MariDB shell
```
exit
```

Run the SQL supplied by the developers (these commands should run silently)

mariadb < 01_build_trs_db.sql
mariadb < 02_add_users.sql
mariadb < 03_add_reservations.sql
mariadb < 04_create_mysql_trs_user.sql

Check that the DB was built, by logging on as the newly created DB user trs_user. Look in create_mysql_trs_user.sql to determine the password.
```
mysql -u trs_user -p
```
List the application users:
```
SELECT * FROM trs.users;
```
List the available meeting times users:
```
SELECT * FROM trs.reservations;
```

Part C: Configure web01 and install the trs php application

Verify that we can access the trs DB from web01
```
mariadb --host db01 --user trs_user -p
```
Run an SQL query to list all the trs application users.
Copy all the trs PHP files to /var/www/html/trs
Test our work with a browser. http://10.1.1.201/trs/trs.php

You will likely need to do a little trouble shooting now

Part D: Load Balancing

In many cases we use horizontal scaling to increase capacity. We can increase capacity by adding a web server and using a load balancer to spread the users across the web servers. We will use haproxy as our load balancer.

Clone web02 from web01
Clone lb01 from bookworm_min
Install haproxy on lb01

Confiugre haproxy to froward http requests to w01 and w02 by appending this fragment to /etc/haproxy/haproxy.cfg

frontend http
  bind 10.1.1.203:80
  mode http
  default_backend web-backend

backend web-backend
   balance roundrobin
   server web01 10.1.1.201:80 check
   server web02 10.1.1.202:80 check

Part D: Test from multiple browsers

Test your handiwork from at least two browsers connecting to the bridged adapter on lb01.

Pay attention to the server=[web01|web02]message on each page.
Do you stay on a server?
Log in and see how things go.

If you think everything is fine, you are likely mistaken - talk to your instructor.

Part E: Make it sticky

Tying a user to a specific back-end server for an entire 'session' is very important for web applications to run smoothly.

Here's a nicely written article describing sticky sessions.

Part F: Grading

Demonstrate your trs to your instructor.

Clean up

You will need web01 and db01 for future labs.