Ansible 使用 setup 取得 Managed node 的 facts

官方文件介紹如下：

This module is automatically called by playbooks to gather useful variables about remote hosts that can be used in playbooks. It can also be executed directly by /usr/bin/ansible to check what variables are available to a host. Ansible provides many facts about the system, automatically.

Ad-Hoc Commands

凍仁一般會(huì)先使用 Ad-Hoc Commands 呼叫 setup 看看有哪些用的上的資訊，這對(duì)撰寫些較復(fù)雜的 Playbooks 時(shí)是很有用的。

底下凍仁將使用 chusiang/ansible-managed-node:ubuntu-14.04 這個(gè) Docker image 作為 Managed node。

1. 借由 less 快速搜尋所有的變數(shù)。¹

   $ ansible all -m setup | less
   server1 | SUCCESS => {
      "ansible_facts": {
          "ansible_all_ipv4_addresses": [
              "172.19.0.2"
          ],
          "ansible_all_ipv6_addresses": [
              "fe80::42:acff:fe13:2"
          ],
          "ansible_architecture": "x86_64",
          "ansible_bios_date": "03/14/2014",
          "ansible_bios_version": "1.00",
          "ansible_cmdline": {
              "com.docker.database": "com.docker.driver.amd64-linux",
              "com.docker.driver": "com.docker.driver.amd64-linux,",
              "console": "ttyS0",
              "earlyprintk": "serial",
              "mobyplatform": "mac",
              "ntp": "gateway"
          },
          "ansible_date_time": {
              "date": "2016-12-13",
   :
   

2. 搭配 filter 將發(fā)行版本 (distribution) 的資訊給過濾出來。

   $ ansible all -m setup -a "filter=ansible_distribution*"
   server1 | SUCCESS => {
      "ansible_facts": {
          "ansible_distribution": "Ubuntu",
          "ansible_distribution_major_version": "14",
          "ansible_distribution_release": "trusty",
          "ansible_distribution_version": "14.04"
      },
      "changed": false
   }
   

3. 取得套件管理員的種類資訊，此例取得的值為 apt。

   $ ansible all -m setup -a "filter=ansible_pkg_mgr"
   server1 | SUCCESS => {
      "ansible_facts": {
          "ansible_pkg_mgr": "apt"
      },
      "changed": false
   }
   

撰寫跨 Linux distribution 的 Playbooks

取得 ansible_pkg_mgr 后，我們可以 Playbooks 里加個(gè)判斷式使用。

1. 建立支持 Debian, Ubuntu, CentOS 安裝 Vim 的 playbook。

   $ 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 yum packages
        yum: name=vim-minimal state=present
        when: ansible_pkg_mgr == "yum"
   
   # vim:ft=ansible :
   

2. 執(zhí)行 playbook，且當(dāng)條件不符時(shí)，即會(huì)跳過該 task。。

   $ ansible-playbook setup_vim.yml
   
   PLAY [Setup the vim] **************************************************
   
   TASK [setup] **********************************************************
   ok: [server1]
   
   TASK [install apt packages] *******************************************
   changed: [server1]
   
   TASK [install yum packages] *******************************************
   skipping: [server1]
   
   PLAY RECAP ************************************************************
   server1           : ok=2    changed=1    unreachable=0    failed=0
   

后話

setup module 是每位 Ansibler 一定會(huì)接觸到的！我們可以善加利用它，并與各種需求搭配使用，這樣會(huì)讓 Playbooks 更具彈性且易于維護(hù)。

相關(guān)連結(jié)

• chusiang.vim-and-vi-mode | Ansible Galaxy
• 怎么用 filter 取得 setup 的第 2 層值？ | ansible-tw/AMA

¹. 在 less 里我們可使用 / + 關(guān)鍵字 + Enter 進(jìn)行搜尋。 ?