Intro

Find (or write) a tiered Web Application that makes use of a remote relational database (Wordpress, Django, wiki.js or similar). Your job is to make your application's presentation and business/logic redundant. You have been provided three new Ubuntu Server Virtual machines with which to make this happen (hooray for netplan). Here's two sample demos.

• Application Redundancy Part 1 - DB Redundancy
• Application Redundancy Part 2 - Application Redundancy

Steps

1. Set up networking on u1, u2, u3 using netplan
2. Install MariaDB on u1,2,3
3. Make Database redundant across u1,2,3
4. Create a web application

Networking

Use netplan to assign U1,2,3 addresses of 10.0.5.201,202,203 respectively

network:
  version: 2
  renderer: networkd
  ethernets:
    ens160:
      dhcp4: no
      addresses:
        - 10.0.5.201/24 
      gateway4: 10.0.5.1
      nameservers:
        addresses: [10.0.5.1, 8.8.8.8]

Change the IP address as needed

MariaDB

I had severe difficulty installing mariadb. My first install went great across all boxes, and the configuration of the Galera cluster seemed to be working when I wrote it. However when I tried to restart the mariadb service, it failed every single time. I attempted to remove mariadb and reinstall it, that did not work. I attempted to remove the galera cluster configuration, which shouldn't have had an impact on mariadb ability to start its own service, this did not work. I tried troubleshooting on u1 as to not waste my time repeating all the steps on all the boxes and nothing worked. The worst part is there were no logs whatsoever. I ran 'journalctl -xeu mariadb.service' as the program instructed, and I also checked the default log location for mysql /var/logs/mysql/error and there were no entries in either. I worked with a peer in the lab and none of their troubleshooting steps worked either. No matter what we did, every time I attempted to start the mariadb service it failed with no error codes and no error logs. This has prevented me from completing this lab.

Below are the steps I took for installation and removal of mariadb

installation

sudo apt-get update
sudo apt-get install mariadb-server -y
sudo systemctl start mariadb      
sudo systemctl status mariadb
sudo mysql_secure_installation

Enter current password for root (enter for none):
Switch to unix_socket authentication [Y/n] n
Change the root password? [Y/n] Y
New password:
Re-enter new password:
Remove anonymous users? [Y/n] Y
Disallow root login remotely? [Y/n] Y
Remove test database and access to it? [Y/n] Y
Reload privilege tables now? [Y/n] Y

removal

sudo apt-get purge mariadb-* 
sudo apt-get autoremove
sudo apt-get autoclean

This worked on every box, but restarting the service failed after configuration. After removing all files associated with mariadb and galera it still failed repeatedly.