Ansible – gather facts

測試環境 CentOS 9 Stream (虛擬機)

架構需求如下系統可以分為 Control node ( Ansible 控制端) 與 Managed nodes (被 Ansible 控制端)

• Control node ( Ansible 控制端) IP: 192.168.31.131
• Managed nodes (被 Ansible 控制端) IP: 192.168.31.133 與 192.168.31.178

在執行 Ansible 時 會有一段是 Gathering Facts ,這是做什麼的,我們來看一下要如何應用這一塊,參考資料 – https://chusiang.gitbooks.io/automate-with-ansible/content/13.how-to-get-the-managed-node-facts-with-setup.html

TASK [Gathering Facts] *************************************************************************************************
ok: [node1]
ok: [node2]

• 建立 Ansible 專案目錄

  [root@localhost ~]# mkdir -p ansible_project/inventory
  [root@localhost ~]# cd ansible_project/
  [root@localhost ansible_project]#
  

• 創建 Inventory 文件
  在 inventory/hosts 文件中，定義你的節點：

  [root@localhost ansible_project]# vi inventory/hosts
  [nodes]
  node1 ansible_host=192.168.31.133
  node2 ansible_host=192.168.31.178
  

• 使用 Ad-Hoc Commands 呼叫 setup

  [root@localhost ansible_project]# ansible nodes -m setup -i inventory/hosts
  node2 | SUCCESS => {
      "ansible_facts": {
          "ansible_all_ipv4_addresses": [
              "192.168.31.178"
          ],
          "ansible_all_ipv6_addresses": [
              "fe80::20c:29ff:fe6f:ce28"
          ],
          "ansible_apparmor": {
              "status": "disabled"
          },
          "ansible_architecture": "x86_64",
          "ansible_bios_date": "11/12/2020",
          "ansible_bios_vendor": "Phoenix Technologies LTD",
          "ansible_bios_version": "6.00",
          "ansible_board_asset_tag": "NA",
          "ansible_board_name": "440BX Desktop Reference Platform",
          "ansible_board_serial": "None",
          "ansible_board_vendor": "Intel Corporation",
          "ansible_board_version": "None",
          "ansible_chassis_asset_tag": "No Asset Tag",
          "ansible_chassis_serial": "None",
          "ansible_chassis_vendor": "No Enclosure",
          "ansible_chassis_version": "N/A",
          "ansible_cmdline": {
              "BOOT_IMAGE": "(hd0,msdos1)/vmlinuz-5.14.0-452.el9.x86_64",
              "crashkernel": "1G-4G:192M,4G-64G:256M,64G-:512M",
              "quiet": true,
              "rd.lvm.lv": "cs/swap",
              "resume": "/dev/mapper/cs-swap",
              "rhgb": true,
              "ro": true,
              "root": "/dev/mapper/cs-root"
          },
  ....
  

  因為資訊太多沒抓出所有的資料.

• 參數 -a filter=
  可以透過參數 -a filter= 來指定要看哪一個參數值.

  [root@localhost ansible_project]# ansible nodes -m setup -i inventory/hosts -a "filter=ansible_distribution*"
  node1 | SUCCESS => {
      "ansible_facts": {
          "ansible_distribution": "CentOS",
          "ansible_distribution_file_parsed": true,
          "ansible_distribution_file_path": "/etc/centos-release",
          "ansible_distribution_file_variety": "CentOS",
          "ansible_distribution_major_version": "9",
          "ansible_distribution_release": "Stream",
          "ansible_distribution_version": "9",
          "discovered_interpreter_python": "/usr/bin/python3"
      },
      "changed": false
  }
  node2 | SUCCESS => {
      "ansible_facts": {
          "ansible_distribution": "CentOS",
          "ansible_distribution_file_parsed": true,
          "ansible_distribution_file_path": "/etc/centos-release",
          "ansible_distribution_file_variety": "CentOS",
          "ansible_distribution_major_version": "9",
          "ansible_distribution_release": "Stream",
          "ansible_distribution_version": "9",
          "discovered_interpreter_python": "/usr/bin/python3"
      },
      "changed": false
  }
  

這些資料可以怎麼應用呢?

我們可以利用 ansible_distribution 來判斷系統使用哪一個系統,進而判斷安裝程式需要使用 apt – Ubuntu 或是 dnf – CentOS / RHEL / Fedora

[root@localhost ansible_project]# ansible nodes -m setup -i inventory/hosts -a "filter=ansible_pkg_mgr"
node2 | SUCCESS => {
    "ansible_facts": {
        "ansible_pkg_mgr": "dnf",
        "discovered_interpreter_python": "/usr/bin/python3"
    },
    "changed": false
}
node1 | SUCCESS => {
    "ansible_facts": {
        "ansible_pkg_mgr": "dnf",
        "discovered_interpreter_python": "/usr/bin/python3"
    },
    "changed": false
}

實際範例 (建議可以用 nano 的編輯器, copy Paste 以下資料就不會出問題)

[root@localhost ansible_project]# vim setup_vim.yml
---

- name: Setup the vim
  hosts: all
  become: true
  tasks:

   # Debian, Ubuntu.
   - name: install apt packages
     apt: name=vim state=present
     when: ansible_pkg_mgr == "apt"

   # CentOS.
   - name: install dnf packages
     dnf: name=vim-minimal state=present
     when: ansible_pkg_mgr == "dnf"

執行

[root@localhost ansible_project]# ansible-playbook -i inventory/hosts setup_vim.yml
PLAY [Setup the vim] ***************************************************************************************************

TASK [Gathering Facts] *************************************************************************************************
ok: [node2]
ok: [node1]

TASK [install apt packages] ********************************************************************************************
skipping: [node1]
skipping: [node2]

TASK [install dnf packages] ********************************************************************************************
ok: [node2]
ok: [node1]

PLAY RECAP *************************************************************************************************************
node1                      : ok=2    changed=0    unreachable=0    failed=0    skipped=1    rescued=0    ignored=0
node2                      : ok=2    changed=0    unreachable=0    failed=0    skipped=1    rescued=0    ignored=0

因為 2 台 Managed nodes (被 Ansible 控制端) 都是 CentOS 所以都是使用 dnf 來安裝套件.