Ansible 7 of 9: Conditionals

Background

Use conditionals to control the execution of tasks and playbooks based on specific conditions or values.

1 of 16. Open Cloud9

2 of 16. Provision the infrastructure using Terraform

Update the "main.tf" with a host03. The host03 will be a different OS.


resource "aws_instance" "host03" {
  ami           = "ami-01e5ff16fd6e8c542"
  instance_type = "t2.micro"
	key_name = "tcb-ansible-key"
  vpc_security_group_ids = [aws_security_group.secgroup.id]
	provisioner "local-exec" {
	  command = "sleep 30; ssh-keyscan ${self.private_ip} >> ~/.ssh/known_hosts"
	}
  tags = {
    Name = "host03"
  }

}


output "host03_private_ip" {
  value = aws_instance.host03.private_ip
}


pwd
cd ansible-tasks
terraform apply -auto-approve

3 of 16. update the inventory file "hosts" with Private IP per terraform output

Make sure to add an entry for the host03. Note that host03 is running Debian, and the default user on Debian is 'admin'. Use the ping module to validate connectivity to the hosts.


aws ec2 describe-instances \
    --query 'Reservations[*].Instances[*].{Instance:InstanceId,Name:Tags[?Key==`Name`]|[0].Value,PublicIP:PublicIpAddress,PrivateIP:PrivateIpAddress,State:State.Name}' \
    --output table


cat hosts
ansible all -m ping

4 of 16. Try the gather_facts module against host01.

You can get all sorts of information with "gather_facts".

ansible host01 -m gather_facts

5 of 16. Try the setup module against host02


ansible host02 -m setup

6 of 16. You can filter the output of the setup module

Try a filter for "ansible_distribution" and "python_version"


ansible host01 -m setup -a "filter=ansible_distribution"
ansible host02 -m setup -a "filter=ansible_distribution"
ansible host03 -m setup -a "filter=ansible_distribution"
ansible host01 -m setup -a "filter=ansible_python_version"
ansible host02 -m setup -a "filter=ansible_python_version"
ansible host03 -m setup -a "filter=ansible_python_version"

7 of 16. You can also use grep to grab specific parts of the output


ansible all -m setup | grep 'ansible_hostname\|ansible_os_family\|ansible_python_version\|ansible_pkg_mgr'

8 of 16. Create the playbook: install-webserver-conditional.yml

It refers to ansible_distribution, which you should be familiar with. Here, it should conditionally install a web server using the appropriate method, dependent upon the package manager for the operating system. Note that the cache update is included in the tasks.


- name: Installing Apache
  hosts: all
  become: yes
  tasks:
    - name: Setup Apache - Debian
      apt:
        update_cache: yes
        name: apache2
        state: latest
      when: ansible_distribution == 'Debian'

    - name: Start Apache - Debian
      service:
        name: apache2
        state: started
      when: ansible_distribution == 'Debian'

    - name: Setup Apache - RHEL
      yum:
        name: httpd
        state: latest
      when: ansible_distribution == 'RedHat'

    - name: Start - RHEL
      service:
        name: httpd
        enabled: true
        state: started
      when: ansible_distribution == 'RedHat'

9 of 16. Note: You can use the "in" operator to compare multiple values


when: ansible_distribution in ["Debian", "Ubuntu"]

10 of 16. Run the Ansible Playbook to install the webservers

This will use your conditionals to choose which installer to run, depending on the host OS


ansible-playbook install-webserver-conditional.yml

11 of 16. Check the status of apache on the hosts.

Note: The RedHat hosts are checked differently than the Debian hosts.


ansible all -m shell -a "systemctl status httpd" -b
ansible all -m shell -a "systemctl status apache2" -b

12 of 16. Connect to the web servers via public IP.

Check the URLs, and validate that web server is running on the hosts.


aws ec2 describe-instances \
    --query 'Reservations[*].Instances[*].{Instance:InstanceId,Name:Tags[?Key==`Name`]|[0].Value,PublicIP:PublicIpAddress,PrivateIP:PrivateIpAddress,State:State.Name}' \
    --output table

13 of 16. Create an index.html file

Populate index.html with the contents below


touch index.html


<html>
<head>
    <style>
        body {
            background-color: #000000;
            color: #ffffff;
            font-family: Arial, sans-serif;
        }

        .container {
            display: flex;
            justify-content: center;
            align-items: center;
            height: 100vh;
            flex-direction: column;
            text-align: left;
        }

        img {
            max-width: 300px;
            margin-bottom: 20px;
        }
    </style>
</head>
<body>
    <div class="container">
        <img src="https://thecloudbootcamp.com/wp-content/uploads/2020/09/The-Cloud-Bootcamp-big-transparent-1024x1024.png.webp" alt="Your Image">
        <h1>Congratulations!</h1>
        <p>CATS: HOW ARE YOU GENTLEMEN !!</p>
        <p>CATS: ALL YOUR BASE ARE BELONG TO US.</p>
        <p>CATS: YOU ARE ON THE WAY TO DESTRUCTION.</p>
        <p>CAPTAIN: WHAT YOU SAY !!</p>
        <p>CATS: YOU HAVE NO CHANCE TO SURVIVE MAKE YOUR TIME.</p>
        <p>CATS: HA HA HA HA ....</p>
    </div>
</body>
</html>

14 of 16. Copy the sample index.html to host02

Obviously, validate that the file displays correctly.


ansible host02 -m copy -a "src=index.html dest=/var/www/html" -b

15 of 16. Note: the file copy can be included in your .yml file


   - name: copy index.html
      copy:
        src: ~/my-local-directory/index.html
        dest: /var/www/html/


ansible-playbook install-webserver-conditional.yml

16 of 16. Cleanup

Destroy the infrastructure using Terraform


cd ansible-tasks
terraform destroy -auto-approve
aws ec2 describe-instances \
    --query 'Reservations[*].Instances[*].{Instance:InstanceId,Name:Tags[?Key==`Name`]|[0].Value,PublicIP:PublicIpAddress,PrivateIP:PrivateIpAddress,State:State.Name}' \
    --output table