[Ansible] Ansible을 사용하여 Cron 작업 등록하기

Ansible을 통해 Cron 모듈을 통해 배치성 작업을 등록하려한다. 하지만 고려해야할 포인트가 몇가지 있다.

1. 기존 서버에 Cron 패키지가 설치 되어있는가?
2. 하나의 매니페스트로 일반적으로 사용하는 OS의 Job케이스를 지원할 수 있는가?

기존 서버에 패키지가 설치되어 있지않은 경우가 있을 수 있다. 어차피 Cron 작업을 등록해야하는거라면, 설치작업부터 진행한다.

두 번째 패키지 설치 시 OS에 따라 패키지 명이 다를 수 있다. 모든 Linux에서 동일한 Cron 패키지를 지원하지않는다. 예를 들어, Ubuntu나 Centos7.x, Redhat7,x 때의 버전들은 지원하지만 이후 최신버전이나 AMZN2,3, Fedofa의 경우 Cronie라는 패키지를 설치해야한다.

위 조건을 충족시키기 위해 node의 Facts를 수집하여 Cron 혹은 Cronie를 설치하도록 작업을 등록하고, 이후 이 매니페스트로 다른 작업을 등록하기 위해 작업정보는 변수처리하여 명령어로 인수로 받아 처리할 수 있도록 했다.

TL;DR

Ansible Cron모듈을 통해 Nginx Reload 작업을 등록한다.

1. 플레이북 매니페스트 작성하기

--- CreateCronJobs.yaml
- name: Create Cron Jobs
  hosts:
    - localhost
  become: true
  vars:
    cron_job_minute: '0'
    cron_job_hour: '3'
    cron_job_day: '*'
    cron_job_month: '*'
    cron_job_weekday: '*'
    cron_job_command: '/usr/sbin/nginx -s reload'
  tasks:
    - name: Determine package manager based on OS
      set_fact:
        cron_package: "{{ 'cron' if ansible_distribution == 'Ubuntu' else 'cronie' if ansible_distribution in ['CentOS', 'RedHat', 'Amazon', 'Fedora']  }}"

    - name: Install cron package
      package:
        name: "{{ cron_package }}"
        state: present
      when: cron_package != ""

    - name: Add Nginx Reload Job
      cron:
        name: Reload nginx
        job: "{{ cron_job_command }}"
        state: present
        minute: "{{ cron_job_minute }}"
        hour: "{{ cron_job_hour }}"
        day: "{{ cron_job_day }}"
        month: "{{ cron_job_month }}"
        weekday: "{{ cron_job_weekday }}"

    - name: Get Crontab List
      command: 'crontab -l'
      register: crontab_list

    - name: Print Crontab List
      debug:
        var: crontab_list.stdout_lines

2. 플레이북 실행 및 디버깅 확인

[ansible@localhost playbook]$ ansible-playbook CreateCronJobs.yaml
PLAY [Create Cron Jobs] **************************************************************************************************************************************************************************************************************************************************************

TASK [Gathering Facts] ***************************************************************************************************************************************************************************************************************************************************************
ok: [localhost]


TASK [Determine package manager based on OS] *****************************************************************************************************************************************************************************************************************************************
ok: [localhost]


TASK [Install cron package] **********************************************************************************************************************************************************************************************************************************************************
ok: [localhost]


TASK [Add Nginx Reload Job] **********************************************************************************************************************************************************************************************************************************************************
ok: [localhost]


TASK [Get Crontab List] **************************************************************************************************************************************************************************************************************************************************************
changed: [localhost]


TASK [Print Crontab List] ************************************************************************************************************************************************************************************************************************************************************
ok: [localhost] => {
    "crontab_list.stdout_lines": [
        "# Edit this file to introduce tasks to be run by cron.",
        "# ",
        "# Each task to run has to be defined through a single line",
        "# indicating with different fields when the task will be run",
        "# and what command to run for the task",
        "# ",
        "# To define the time you can provide concrete values for",
        "# minute (m), hour (h), day of month (dom), month (mon),",
        "# and day of week (dow) or use '*' in these fields (for 'any').# ",
        "# Notice that tasks will be started based on the cron's system",
        "# daemon's notion of time and timezones.",
        "# ",
        "# Output of the crontab jobs (including errors) is sent through",
        "# email to the user the crontab file belongs to (unless redirected).",
        "# ",
        "# For example, you can run a backup of all your user accounts",
        "# at 5 a.m every week with:",
        "# 0 5 * * 1 tar -zcf /var/backups/home.tgz /home/",
        "# ",
        "# For more information see the manual pages of crontab(5) and cron(8)",
        "# ",
        "# m h  dom mon dow   command",
        "#Ansible: Reload nginx",
        "0 3 * * * /usr/sbin/nginx -s reload"
    ]
}

PLAY RECAP ***************************************************************************************************************************************************************************************************************************************************************************
localhost        : ok=6    changed=1    unreachable=0    failed=0    skipped=0    rescued=0