ansible

ansible is an network automation framework that allow to execute a series of tasks in parallel in a set of machines, it allows for both declarative and procedural approaches to define machine state and environment configurations, it’s based around 2 simple concepts

a list of a task to be executed called playbook
a list of host machines to target called inventory

ℹ️ Note

ansible uses ssh connection and copies python script to execute modules, so the target machine must have ssh enabled and configured and a compatible python interpreter

--- title: ansible inner working --- sequenceDiagram participant ansible_runner participant target ansible_runner ->> target: copies ansible module (python file) target ->> target: executes ansible module

Ansible content can be distributed in the form of roles or collections, where a role is a set of tasks that made a specific action/configuration (e.g. Installing docker) and a collection is a set of roles

Snippets
#

copy script in remote host and set a cronjob

- name: Setup cronjob
  block:

    - name: Copy cronjob script
      ansible.builtin.template:
        src: templates/cronjob.sh.j2
        dest: /usr/local/bin/cronjob.sh
        mode: '755'

    - name: Configure cron to run cronjob
      ansible.builtin.cron:
        name: "cronjob"
        minute: "*"
        hour: "*"
        job: "/usr/local/bin/cronjob.sh > /dev/null 2>&1"

Block rescue for installation procedure and notifications

- name: Do installation operations
  block:
  # tasks ....
  rescue:
    - name: Notify failed installation
      ansible.builtin.uri:
        url: "{{ ntfy_endpoint }}"
        method: POST
        body: "installation on {{ inventory_hostname }} has encounter some issues"

test a variable and fail if it is undefined

- name: Print variables and fail if absent
  block:
    - ansible.builtin.debug:
        var: foo
    - ansible.builtin.fail:
        msg: "{{ foo }} is undefined"
      when: foo is undefined