Ansible: tasks and modules

Let’s add some tasks to our playbook using Ansible modules. Ansible use modules to perform actions on targets and return values from module execution (such as whether a change was performed and action return values)

Module often used by playbooks:

• copy - Copy files to remote locations
• apt – Manages apt-packages
• …

See Ansible module index for all available modules.

Install a package

Update playbook.yml file to install apache2 package (Apache HTTP server) using apt module with the following parameters:

• Install apache2 package
• Ensure cache is updated when using the module (equivalent of running apt-get update)
• Use privilege escalation when running the module (equivalent to using sudo or running command as root)
  • Search for this in Ansible doc ;)

Run your playbook and, on success, ensure Apache has been installed. Apache service should be running and serving the default page:

• Running sudo systemctl status apache2 on the server should show the service status
• Try accessing your server via web browser at it’s address such as http://your-name.training.crafteo.io, the default Apache page should be shown

Try running the playbook a second time and see what happens.

Manage file content

Let’s override the default index.html of our Apache server by instructing Ansible to manage /var/www/html/index.html, the default Apache index file.

Configure your Playbook to copy the index.html file already existing in our repository on the target node such as:

• Local index.html file should be copied at /var/www/html/index.html
• Set index.html permission to 0600
• Set index.html owner and group to www-data and www-data

Run the playbook to apply changes and check on the machine changes were applied (use SSH command to connect to your node: ssh ubuntu@your-name.training.crafteo.io)

• Comment out the task from the playbook and run it again
• Check if the file was deleted

Run a command

Ansible can also run commands on targets. Use an appropriate module to run the following command:

ls -al /var/www/html

Important note: using this method should be avoided when possible. Ansible modules running commands are not idempotent most of the time, you are responsible to ensure the command’s idempotency.

If possible, use an Ansible module instead of running a command. For example, to install apache2, you can run command:

sudo apt-get install apache2

However, the apt Ansible module exists for managing packages, the prefered way is then something like:

- name: install Apache2
  apt:
    name: apache2
    state: present