linuxexpert-practice-labs/labs/ex294/1-2-variables-and-facts/README.md

EX294 1.2: Variables and facts

Give a group and one host their own value of a variable, print facts from a playbook, and add a custom fact to a node.

Before you start

This VM is the control node. The lab installs ansible-core and creates the user greg (password Lab-Pass-1), who has an SSH key. Work as greg (su - greg as root), in /home/greg/ansible: its ansible.cfg reads the inventory inventory, which has node1 and node2 in the group webservers, and logs in as ansible. There are no variable files yet.

The managed nodes node1 (10.99.1.11) and node2 (10.99.1.12) are AlmaLinux 10 containers with their own users and packages, reached over SSH by name. On each, the user ansible accepts greg's key and may use sudo without a password. For a root shell on a node, sudo podman exec -it node1 bash.

Tasks

1. Set http_port to 80 for the webservers group and to 8080 for node2 alone, and print it from a playbook, /home/greg/ansible/port.yml, that runs on the webservers. node1 prints 80 and node2 8080; with -e http_port=9000 both print 9000.
2. Write /home/greg/ansible/facts.yml, which prints each managed node's distribution, its version and its memory in MiB from facts. Each host's numbers match ansible HOST -m setup -a 'filter=ansible_memtotal_mb' (and ansible_distribution*).
3. Write a custom fact on node1 in /etc/ansible/facts.d/role.fact, with the section [general] and role=web. ansible node1 -m setup -a 'filter=ansible_local' shows "role": "web" under general.

Hints

• group_vars/webservers.yml and host_vars/node2.yml next to the inventory; ansible-inventory --host node2 shows what a host gets.
• ansible.builtin.debug with msg: "{{ http_port }}" or var: http_port.
• ansible_facts['distribution'], ['distribution_version'] and ['memtotal_mb'].
• The fact file is plain INI and must not be executable (an executable .fact is run as a program). Write it with ansible.builtin.copy and become: true, or by hand on the node.