Sample systemd timer unit to run ansible-pull every 30 minutes

ansiblePull.service

[Unit]
Description=Runs ansible-pull to get common server configuration
Wants=ansiblePull.timer

[Service]
Type=oneshot
ExecStart=/usr/bin/ansible-pull -U https://github.com/<username>/<repo_name>.git --accept-host-key -i hosts --vault-password-file /root/.vault_password

[Install]
WantedBy=multi-user.target

ansiblePull.timer

[Unit]
Description=starts ansible-pull to get common server configuration
Requires=ansiblePull.service

[Timer]
Unit=ansiblePull.service
OnCalendar=*:0/30:00

[Install]
WantedBy=timers.target

main.yml

---
- name: My task
  hosts: all
  tasks:
    - name: install software-properties-common and update apt cache
      apt:
        name: software-properties-common
        state: latest
        update_cache: yes
        cache_valid_time: 3600
      become: yes

    - name: add apt repository ppa ansible
      apt_repository:
        repo: ppa:ansible/ansible
      become: yes

    - name: install ansible
      apt:
        name: ansible
        state: latest
      become: yes

    - name: deploy the vault_password file
      copy:
        src: ../files/.vault_password
        dest: /root/.vault_password
        owner: root
        group: root
        mode: "0600"
      become: yes

    - name: install git
      apt:
        name: git
        state: latest
      become: yes

    - name: create the ansiblePull.service file
      copy:
        src: ../files/ansiblePull.service
        dest: /etc/systemd/system/ansiblePull.service
      become: yes

    - name: create the ansiblePull.timer file
      copy:
        src: ../files/ansiblePull.timer
        dest: /etc/systemd/system/ansiblePull.timer
      become: yes

    - name: make sure that the timer service is started
      systemd:
        name: ansiblePull.timer
        state: started
        enabled: yes
        daemon_reload: yes
      become: yes