Ansible

Agentless automation over SSH. No agents to install on managed nodes -- just Python on targets and SSH access. All modules are idempotent by default: running a playbook twice produces the same result.

Ad-Hoc Commands

# Ping all hosts
ansible all -m ping

# Run command on web servers
ansible webservers -m command -a "uptime"
ansible webservers -m shell -a "df -h | grep /dev/sda"

# Copy file
ansible webservers -m copy -a "src=./app.conf dest=/etc/app.conf owner=root mode=0644"

# Install package
ansible webservers -m apt -a "name=nginx state=present" --become