🐧 Automated Linux Tasks

In this repo we will:

• Create a Linux CentOS machine on AWS using Terraform.
• Create Incorta user using Ansible.
• Allow Incorta user to switch to root without a password using Ansible.
• Attach external disk with ext4 format then mount it under /incorta with Incorta ownership, using Terraform
• Install all JAVA versions (OpenJDK 8 & 11, Oracle JDK8) using Ansible.
• Create a switchable bash script to switch between JAVA versions.
• Install MySQL 5.6 using Ansible.
• Use SSH tunneling to connect to MySQL.
• Write a bash script to get the CPU and Memory (Free, Utilized, and Cached) utilization five times separated by 1 minute.

Prerequisites

• Python 3
• Ansible 2.9.6
• Terraform >= 0.14.9
• AWS account

(1) Provision The Infrastructure on AWS using Terraform

terraform apply

Terraform code that:

• Create CentOS 7 EC2 instance.
• Open the SSH port.
• Create EBS volume with 30 GiP.
• Attach this volume to the EC2 instance.

(2) Configure the EC2 server using Ansible

ansible-playbook -i hosts ansible-playbook.yml --private-key /the/path/to/file.pem

Ansible playbook that:

• Install OpenJDK 8 & 11, Oracle JDK 8.
• Remove MariaDB (to avoid any conflicts between MariaDB & MySQL)
• Install MySQL 5.6 and start its service.
• Create "incorta" user with sudo privileges.
• Allow "incorta" user to switch to root without a password.
• Create "/incorta" directory.
• Mount the external disk under "/incorta" with ext4 format.
• Copy the shell scripts to the target host.

(3) Use SSH tunneling to connect to MySQL

ssh -L 3306:localhost:3306 -i /the/path/to/file.pem centos@IP-ADDRESS

(4) Bash script to get the CPU and Memory utilization

After clone this repo, change the file permission to be executable:

sudo chmod +x ./utilization.sh

Then, run the script:

./utilization.sh

The expected output will be like this:

-----------------------------------------------------------------
OS NAME="CentOS Linux"
-----------------------------------------------------------------
Min   CPU(%)   Free Memory(%)  Used Memory(%)  Cached Memory(%)
-----------------------------------------------------------------
1     23.32%   2.54%           80.60%          16.86%
2     23.32%   2.82%           80.58%          16.60%
3     23.32%   2.84%           80.56%          16.60%
4     23.32%   2.84%           80.56%          16.60%
5     23.32%   2.84%           80.56%          16.60%
-----------------------------------------------------------------

(5) Bash script to switch between JAVA versions

You can use this command:

sudo update-alternatives --config java

Or use this for simplicity:

./java-switcher.sh

The expected output will be like this:

There are 3 programs which provide 'java'.

  Selection    Command
-----------------------------------------------
   1           java-11-openjdk.x86_64 (/usr/lib/jvm/java-11-openjdk-11.0.11.0.9-1.el7_9.x86_64/bin/java)
*+ 2           java-1.8.0-openjdk.x86_64 (/usr/lib/jvm/java-1.8.0-openjdk-1.8.0.292.b10-1.el7_9.x86_64/jre/bin/java)
   3           /usr/java/jdk1.8.0_291-amd64/bin/java

Enter to keep the current selection[+], or type selection number: