Loops¶

What You'll Learn¶

• The loop: keyword and the item variable
• Looping over a list of dictionaries
• Why loop replaced with_items in modern playbooks

Minimal Example¶

- name: Install a list of packages
  ansible.builtin.package:
    name: "{{ item }}"
    state: present
  loop:
    - nginx
    - curl
    - git

Runs the task three times, once per list item, with item bound to the current value each time.

Looping Over a List of Dictionaries¶

- name: Create application users
  ansible.builtin.user:
    name: "{{ item.name }}"
    groups: "{{ item.groups }}"
    shell: /bin/bash
  loop:
    - { name: deploy, groups: sudo }
    - { name: appuser, groups: docker }

Renaming the Loop Variable¶

- name: Ensure config directories exist
  ansible.builtin.file:
    path: "/etc/app/{{ dir_name }}"
    state: directory
  loop:
    - conf.d
    - templates
  loop_control:
    loop_var: dir_name

loop_control.loop_var matters when a loop is inside an include_tasks that itself contains another loop — without renaming, the inner loop's item would shadow the outer one.

loop vs. Legacy with_*¶

# Legacy — still works, avoid in new playbooks
- ansible.builtin.package:
    name: "{{ item }}"
  with_items:
    - nginx
    - curl

# Modern — use this
- ansible.builtin.package:
    name: "{{ item }}"
  loop:
    - nginx
    - curl

with_items and its siblings (with_dict, with_fileglob, ...) were Ansible's original looping mechanism, each backed by a different "lookup plugin" with its own quirks. loop (paired with a Jinja2 filter when you need with_dict-style behavior — loop: "{{ my_dict | dict2items }}") is the single, more predictable modern replacement. Both still work; only loop should appear in new code.

Common Mistakes¶

• Using with_items/with_dict in new playbooks out of habit or copied examples.
• Looping over hundreds of items expecting parallelism — by default, loop iterations run sequentially within a single host/task; see Async and Poll for genuinely parallel per-item work.
• Nesting loops without renaming loop_var, causing the inner loop to silently overwrite the outer item.

Interview Questions¶

• What's the difference between loop and with_items?
• Does a loop run its iterations in parallel or sequentially by default?
• When would you use loop_control.loop_var?

Next¶

Continue to Handlers.