linuxexpert-practice-labs/labs/ex294/1-4-loops-conditions-and-failures/README.md

EX294 1.4: Loops, conditions and task failure

Create users from a list of dictionaries, run tasks only where a condition holds, loop over a dictionary, and watch one host fail while the others carry on.

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 nodes, and logs in as ansible.

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. Write /home/greg/ansible/users.yml, which creates the users alice (in the group wheel) and bob on node1 from a list of dictionaries, in one task. ansible node1 -a 'id alice' shows wheel, and a second run shows both items ok.
2. Write /home/greg/ansible/memory.yml, which prints one message only on hosts with more than 2 GiB of memory and another only on the rest. Each host shows one ok and one skipping.
3. Write /home/greg/ansible/services.yml, which loops over a dictionary of service names and ports with dict2items and prints each pair: one line per key, showing item.key and item.value.
4. Write /home/greg/ansible/fail.yml, in which a task fails on one host while the others carry on to the next task. The recap shows failed=1 for that host only.

Hints

• loop: "{{ users }}" over a list in vars:, with name: "{{ item.name }}" and groups: "{{ item.groups }}".
• when: ansible_facts['memtotal_mb'] > 2048, and <= 2048 for the other task. All the hosts here have the same memory, so they all print the same message.
• loop: "{{ ports | dict2items }}" with msg: "{{ item.key }} {{ item.value }}".
• ansible.builtin.command: /bin/false with when: inventory_hostname == 'node1', then any task after it. Don't use ignore_errors.