06 - Loops

Learn how to iterate over lists and files to avoid repetition.

What You'll Learn

• Iterating over lists with with_items
• Iterating over files with with_filetree
• Using the {{ item }} variable
• Accessing file properties in loops

Quick Start

cd examples/06-loops

# Run list iteration example
mooncake run --config with-items.yml

# Run file tree iteration example
mooncake run --config with-filetree/config.yml

Examples Included

1. with-items.yml - List Iteration

Iterate over lists of items:

- vars:
    packages:
      - neovim
      - ripgrep
      - fzf

- name: Install package
  shell: brew install {{ item }}
  with_items: "{{ packages }}"

What it does: - Defines lists in variables - Installs multiple packages - Creates directories for multiple users - Creates user-specific config files

2. with-filetree/ - File Tree Iteration

Iterate over files in a directory:

- name: Copy dotfile
  shell: cp "{{ item.src }}" "/tmp/backup/{{ item.name }}"
  with_filetree: ./files

What it does: - Iterates over files in ./files/ directory - Copies dotfiles to backup location - Filters directories vs files - Displays file properties

Key Concepts

List Iteration (with_items)

- vars:
    users: [alice, bob, charlie]

- name: Create user directory
  file:
    path: "/home/{{ item }}"
    state: directory
  with_items: "{{ users }}"

This creates: - /home/alice - /home/bob - /home/charlie

File Tree Iteration (with_filetree)

- name: Process file
  shell: echo "Processing {{ item.name }}"
  with_filetree: ./dotfiles
  when: item.is_dir == false

Available properties: - item.src - Full source path - item.name - File name - item.is_dir - Boolean, true if directory

Filtering in Loops

Skip directories:

- name: Copy files only
  shell: cp "{{ item.src }}" "/tmp/{{ item.name }}"
  with_filetree: ./files
  when: item.is_dir == false

Real-World Use Cases

with_items: - Installing multiple packages - Creating multiple users/groups - Setting up multiple services - Deploying to multiple servers

with_filetree: - Managing dotfiles - Deploying configuration directories - Backing up files - Processing file collections

Testing

# List iteration
mooncake run --config with-items.yml

# Check created files
ls -la /tmp/users/

# File tree iteration
mooncake run --config with-filetree/config.yml

# Check backed up files
ls -la /tmp/dotfiles-backup/

Next Steps

Continue to 07-register to learn about capturing command output.