Ansible 101

Trishna Guha (@trishnag)
Associate Software Engineer
Ansible by Red Hat

Ansible is so simple but still powerful

• Automation

• Configuration Management

• Application Deployment

Key Points

• Written in Python
• Uses SSH
• Agentless

Key Words

• Playbook
• Tasks
• Inventory
• Roles

Playbook

• Entrypoint of Automation
• Yaml File

---
- name: main playbook
  hosts: localhost
  become: yes
  become_method: sudo

  tasks:
    - name: install httpd
      dnf:
        name: httpd
        state: latest

Tasks

• Operations to be perfomed

---
- name: main playbook
  hosts: localhost
  become: yes
  become_method: sudo

  tasks:
    - name: install httpd
      dnf:
        name: httpd
        state: latest

    - debug:
        msg: "{{ result }}"


    - ping:

Inventory

• Hosts file
• INI file with list of groups of hosts

[atomic]
192.168.1.1 ansible_ssh_private_key_file=<SSH_KEY_FIILE>

[nxos]
172.24.4.16 ansible_connection=local ansible_user=user ansible_ssh_pass=pass

[targets]
localhost              ansible_connection=local
other1.example.com     ansible_connection=ssh        ansible_user=mpdehaan
other2.example.com     ansible_connection=ssh        ansible_user=mdehaan

Roles

• Collection of tasks, playbooks

• Run multiple times

• One very large playbooks ?

• Organize and Manage Files in maintainable manner

Variables

• Follow Variable Convention
• Keep Plays and Variables definition separate

# vars/guests.yml

---
domain: atomic-node
image: Fedora-Atomic-25-20170215.1.x86_64
cpu: 1
mem: 1536
os:
  variant: fedora23
path: /tmp

Continued

---
# This playbook creates VM from the QCOW2 Image

- include_vars:
    file: vars/guests.yml



- name: Copy qcow2 image to the instance qcow2
  copy:
    src: '{{ path }}/{{ image }}.qcow2'
    dest: /var/lib/libvirt/images/{{ domain }}.qcow2

- name: Create VM from QCOW2
  shell: virt-install --quiet --import --name={{ domain }}
         --os-variant={{ os.variant }} --ram={{ mem }} --vcpus={{ cpu }} 
         --disk path=/var/lib/libvirt/images/{{ domain }}.qcow2,format=qcow2,bus=virtio 
         --disk path=/var/lib/libvirt/images/{{ domain }}.cidata.iso,device=cdrom,readonly=on 
         --network network=default --noautoconsole

- name: Make sure that the VM is running
  virt: name={{ domain }} command=start
  ignore_errors: yes

Single Playbook to Manage all

---
# Main Entrypoint


- name: Main Playbook
  hosts: localhost
  become: yes
  become_method: sudo

  tasks:
  - include: create-vm.yml
  - include: compose.yml

Make Ansible Repeat your task

---
# This playbook installs requirements

- name: Install the list of required packages
  package: name={{ item }} state=installed
  with_items:
  - genisoimage
  - libvirt
  - libselinux-python
  - qemu-img
  - rpm-ostree
  - ostree
  - virt-install


- name: Download daemon rpm and Install
  command: "{{ item }}"
  with_items:
    - wget -P /tmp http://libslack.org/daemon/download/daemon-0.6.4-1.x86_64.rpm
    - rpm --install /tmp/daemon-0.6.4-1.x86_64.rpm
  ignore_errors: yes


- name: Create directory structure
  file: path={{ item }} state=directory mode=750
  with_items:
    - "/srv/repo"
    - "/srv/cache"
    - "{{ abs_path }}"

And a lot more....

https://docs.ansible.com

https://www.ansible.com

Source Code

• https://github.com/ansible/ansible
• https://github.com/ansible/ansible/blob/devel/CONTRIBUTING.md
• https://github.com/ansible/ansible/blob/devel/CODING_GUIDELINES.md
• https://github.com/ansible/ansible/tree/devel/docs/docsite/rst/dev_guide