案例：升级CentOS操作系统

说明

安装完CentOS之后首次升级整个操作系统，不过，升级前先修改repo配置，确保改成正确的版本

• 修改配置文件

对于简单的配置文件修改可以采用复制方法，复杂的替换需要使用模块。

参考 Which is the best way to make config changes in conf files in ansible

• 使用command模块执行命令(复杂命令使用shell模块)

• 使用yum模块进行升级

初步的playbook

- hosts: new
  tasks:
    - name: clean no need repo config
      command: rm -f /etc/yum.repos.d/*
      notify:
        - Remove all old repo config
    - name: cp rhel.repo
      copy: src=rhel.repo dest=/etc/yum.repos.d/rhel.repo owner=root group=root mode=0644
    - name: upgrade all packages
      yum: name=* state=latest

copy和yum模块不能使用notify，而command模块可以使用notify

建议不要使用rm命令，改为使用file模块的state=absent，因为执行时候有提示 [WARNING]: Consider using file module with state=absent rather than running rm

改进后的playbook

- hosts: new
  tasks:
    - shell: ls -1 /etc/yum.repos.d
      register: contents
    - file: path=/etc/yum.repos.d/{{ item }} state=absent
      with_items: contents.stdout_lines
    - name: cp rhel.repo
      copy: src=rhel.repo dest=/etc/yum.repos.d/rhel.repo owner=root group=root mode=0644
    - name: upgrade all packages
      yum: name=* state=latest
    - name: cp epel.rpm
      copy: src=epel-release-latest-7.noarch.rpm dest=/tmp/epel-release-latest-7.noarch.rpm
    - name: Install package.
      yum:
         name: /tmp/epel-release-latest-7.noarch.rpm
         state: present

删除目录下多个文件的技巧

参考ansible - delete unmanaged files from directory?，解决的方法是先ls目录下文件，将得到的文件存入变量，然后用这个变量来做absent

- shell: ls -1 /some/dir
  register: contents

- file: path=/some/dir/{{ item }} state=absent
  with_items: contents.stdout_lines
  when: item not in managed_files

从远程目录下载多个文件

How to fetch multiple files from remote machine to local with Ansible也是用了相似的方式，将远程目录下多个文件下载到本地

- shell: (cd /remote; find . -maxdepth 1 -type f) | cut -d'/' -f2
  register: files_to_copy

- fetch: src=/remote/{{ item }} dest=/local/
  with_items: files_to_copy.stdout_lines

另外，synchronise module使用了rsync来

创建远程目录

How to create a directory using Ansible?

- name: Creates directory
  file: path=/src/www state=directory

更多file模块选项

rpm安装

- name: Copy rpm file to server
  copy:
     src: package.rpm
     dest: /tmp/package.rpm

- name: Install package.
  yum:
     name: /tmp/package.rpm
     state: present

前例中设置了安装EPEL以便安装必要的第三方软件包

执行

ansible-playbook upgrade_centos.yml -f 10

sudo

如果ansible的控制台登录到被管理服务器上的帐号是非root的其他帐号，如admin，需要通过sudo指令来执行系统程序安装，则需要在ansible的playbook中设置使用sudo: true

    - name: upgrade all packages
      sudo: true
      yum: name=* state=latest

参考通过sudo安装rpm包

参考

• yum - Manages packages with the yum package manager
• Which is the best way to make config changes in conf files in ansible
• Ansible Playbook to run Shell commands
• Install rpm package using Ansible
• ansible - delete unmanaged files from directory?