Ansible basics

Execute remote command from command line and playbook with ansible.

Execute simple commands on remote node with Ansible from command line

$ ansible target -m ping -u ubuntu -k
SSH password:
10.10.10.1 | success >> {
    "changed": false,
    "ping": "pong"
}
=> target: the host/ip/group in /etc/ansible/hosts file that is being configured
=> -m: the module to call
=> -u: the username to use for ssh connection with the target machine
=> -k: same as "--ask-pass", prompt for asking ssh password for connection

$ ansible webservers -m yum -a "name=acme state=present"
=> -a: the argument of the module

Execute complex commands on remote node with Ansible from playbook

Ansible playbooks include multiple tasks as yaml-formatted file and run together

  • Ansible playbook example and saved as: playbook.yml
---
- hosts: webservers
  vars:
    http_port: 80
    max_clients: 200
  vars_files:
    - /vars/external_vars.yml
  remote_user: root
  tasks:
  - name: ensure apache is at the latest version
    yum: name=httpd state=latest
  - name: write the apache config file
    template: src=/srv/httpd.j2 dest=/etc/httpd.conf
    notify:
    - restart apache
  - name: ensure apache is running (and enable it at boot)
    service: name=httpd state=started enabled=yes
  handlers:
    - name: restart apache
      service: name=httpd state=restarted
  • Run Ansible playbook
$ ansible-playbook playbook.yml
  • Include files for reuse
---
# possibly saved as tasks/foo.yml
- name: placeholder foo
  command: /bin/foo
- name: placeholder bar
  command: /bin/bar

# the task that invoke/include the above foo.yml
  tasks:
    - include: tasks/foo.yml
      vars:
          var1: value1
          var2:
              - value2_1
              - value2_2
  • Pass extra arguments from command line
$ ansible-playbook release.yml --extra-vars "version=1.23.45 other_variable=foo"

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