Ansible

It focuses on reaching a desired state

component

• Inventories
• Playbooks
• Plays
• Tasks
• Modules

Inventories

It is the list of nodes/hosts, can be static or dynamic list from cloud provider like AWS

We can grouped hosts based on location, function & …

We have variables that we can set attribute to hosts like service port, timeout & ….

for creation we have 2 options:
1- simple text
2- inventory script

We can add path of inventory to ansible.cfg file in local directory or /etc/ansible/ansible.cfg
local directory has priority over default ansible.cfg file

–limit: to limit execution of command or playbook on the inventory hosts

Playbook

It is yaml formated

Describe the end state of sth.

Meant to be reusable, so we can keep them under source control to:
1- track changes
2- make them easily available

Play

Multi play is inside a playbook

each play has target (hosts) which include remote user/sudo and execute tasks

Tasks

Each task runs one or more modules with parameters and returned value for that module.

Modules

We can find help (list) for modules on the website or ansible-doc <copy> command

Modules make sure that requested state is achieved as indicate with parameters and if not doing what is need.

example:
yum – mysql-db – ping

Roles, Import, Include

break the playbook into smaller pieces that can be used in (include) in multiple playbook.

Example

- name: Create web server
  hosts: ws
  remote_user: joe
  become_method: sudo
  become: yes
  tasks:
  - name: Install httpd
    yum:
      name: httpd
      state: present
  - name: Check that httpd has started
    service:
      name: httpd
      state: started
  - name: Install firewalld
    yum:
      name: firewalld
      state: present
  - name: Firewall access to https
    firewalld:
      service: http
      permanent: yes
      state: enabled
  - name: Restart the firewalld service to load in the firewall changes
    service:
      name: firewalld
      state: restarted

Run the playbook

ansible-playbook command to run the playboook
-C – test playbook before running
-v – verbose
ansible-palybook -v simple-web.yaml

ad-hoc Command

Indicate which command & options you want to run on a group of nodes as a one-time activity
example:
ansible [ws] -u <user> -m ping