5、Ansible流程控制

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当你的才华还撑不起你的野心的时候，你就应该静下心来学习。
当你的能力还驾驭不了你的目标的时候，你就应该沉下心来历练。
问问自己，想要怎样的人生。

 

 

playbook条件语句

不管是 shell 还是各大编程语言中，流程控制，条件判断这些都是必不可少的，在我们使用 Ansible 的过程中，条件判断的使用频率极其高。

例如：

1.我们使用不同的系统的时候，可以通过判断系统来对软件包进行安装。

2.在 nfs 和 rsync 安装过程中，客户端服务器不需要推送配置文件，之前我们都是写多个play，会影响效率。

3.我们在源码安装nginx的时候，执行第二遍就无法执行了，此时我们就可以进行判断是否安装过。

 

---

【根据不同的操作系统安装apache】

官方示例：

tasks:
  ‐ name: "shut down Debian flavored systems"
    command: /sbin/shutdown ‐t now
    when: ansible_facts['os_family'] == "Debian"
    # note that all variables can be used directly in conditionals without double curly
braces
‐ hosts: web_group
  tasks:
  ‐ name: Install CentOS Httpd
    yum:
      name: httpd
      state: present
#官方
  when: ansible_facts['os_family'] == "CentOS"
#非官方
  when: ansible_distribution == "CentOS"

  ‐ name: Install Ubuntu Httpd
    yum:
      name: apache2
      state: present
    when: ansible_facts['os_family'] == "Ubuntu"

---

【还可以使用括号对条件进行分组】

tasks:
  ‐ name: "shut down CentOS 6 and Debian 7 systems"
  command: /sbin/shutdown ‐t now
  when: (ansible_facts['distribution'] == "CentOS" and
ansible_facts['distribution_major_version'] == "6") or
          (ansible_facts['distribution'] == "Debian" and
  ansible_facts['distribution_major_version'] == "7") 

---

【也可以指定多条件为列表】

tasks:
  ‐ name: "shut down CentOS 6 systems"
  command: /sbin/shutdown ‐t now
  when:
    ‐ ansible_facts['distribution'] == "CentOS"
    ‐ ansible_facts['distribution_major_version'] == "6"

---

【条件运算】

tasks:
  ‐ shell: echo "only on Red Hat 6, derivatives, and later"
  when: ansible_facts['os_family'] == "RedHat" and ansible_facts['lsb']
  ['major_release']|int >= 6 

---

【过滤匹配返回值包含successfu】

  ‐ name: Check Nginx Configure
  command: /usr/sbin/nginx ‐t
  register: result
  ‐ name: Restart web02
  command: /usr/sbin/reboot
  changed_when: result.stderr_lines| match successful
  或者
  changed_when: result.stderr_lines is search successful

---

【rsync服务端推送配置文件】

[root@m01 ~]# cat rsyncd/rsyncd.yml
‐ hosts: rsync_server
  tasks:
    ‐ name: Install Rsyncd Server
      yum:
        name: rsync
        state: present
    ‐ name: Create www Group
      group:
        name: www
        gid: 666
    ‐ name: Create www User
      user:
        name: www
        group: www
        uid: 666
        create_home: false
        shell: /sbin/nologin
    ‐ name: Scp Rsync Config
      copy:
        src: ./rsyncd.j2
        dest: /etc/rsyncd.conf
        owner: root
        group: root
        mode: 0644
     when: ansible_hostname == "backup"
    ‐ name: Create Passwd File
      copy:
        content: 'rsync_backup:123'
        dest: /etc/rsync.passwd
        owner: root
        group: root
        mode: 0600
     when: ansible_hostname == "backup"
    ‐ name: Create backup Directory
      file:
        path: /backup
        state: directory
        mode: 0755
        owner: www
        group: www
        recurse: yes
     when: ansible_hostname == "backup"
    ‐ name: Start Rsyncd Server
      systemd:
        name: rsyncd
        state: started
     when: ansible_hostname == "backup"

---

【rsync客户端推送脚本】

[root@m01 ~]# vim rsync.yml
‐ hosts: rsync_server
  tasks:
    ‐ name: SCP Backup Shell
      copy:
        src: ./backup.sh
        dest: /root/backup.sh
     when: ansible_hostname is match "web*"
#执行结果
PLAY [rsync_server]
********************************************************************************************
********************************************************************************************
**********************************
TASK [Gathering Facts]
********************************************************************************************
********************************************************************************************
*******************************
ok: [web02]
ok: [backup]
ok: [web01]
TASK [SCP Backup Shell]
********************************************************************************************
********************************************************************************************
******************************
skipping: [backup]
changed: [web01]
changed: [web02]
PLAY RECAP
********************************************************************************************
********************************************************************************************
*******************************************
backup : ok=1 changed=0 unreachable=0 failed=0 skipped=1 rescued=0 ignored=0
web01 : ok=2 changed=1 unreachable=0 failed=0 skipped=0 rescued=0 ignored=0
web02 : ok=2 changed=1 unreachable=0 failed=0 skipped=0 rescued=0 ignored=0 

---

【通过register将命令执行结果保存至变量，然后通过when语句进行判断】

‐ hosts: web_group
  tasks:
    ‐ name: Check Httpd Server
      command: systemctl is‐active httpd
      ignore_errors: yes
      register: check_httpd‐ name: debug outprint
      debug: var=check_httpd
    ‐ name: Httpd Restart
      service:
        name: httpd
        state: restarted
     when: check_httpd.rc == 0

playbook循环语句

在之前的学习过程中，我们经常会有传送文件，创建目录之类的操作，创建2个目录就要写两个file模块来创建，如果要 创建100个目录，我们需要写100个file模块？？？妈耶~~~~ 当然不是，只要有循环即可，减少重复性代码。

---

【启动多个服务】

‐ hosts: web_group
  tasks:
    ‐ name: start service
      systemd:
        name: "{{ item }}"
        state: started
      with_items:
        ‐ httpd
        ‐ php‐fpm
        ‐ mariadb

---

【定义变量循环】

‐ name: ensure a list of packages installed
  yum:
    name: "{{ packages }}"
  vars:
    packages:
      ‐ httpd
      ‐ httpd‐tools

‐ hosts: web_group
  tasks:
    ‐ name: ensure a list of packages installed
      yum: name= "{{ item }}" state=present
      with_items:
        ‐ httpd
        ‐ httpd‐tools

---

【字典循环】

1.创建用户

[root@m01 ~]# cat loop.yml
‐ hosts: web_group
  tasks:
    ‐ name: Add Users
      user:
        name: "{{ item.name }}"
        groups: "{{ item.groups }}"
        state: present
  with_items:
    ‐ { name: 'kirin', groups: 'linux' }
    ‐ { name: 'egon', groups: 'python' }

2.拷贝文件

‐ hosts: web_group
  tasks:
    ‐ name: copy conf and code
      copy:
        src: "{{ item.src }}"
        dest: "{{ item.dest }}"
        mode: "{{ item.mode }}"
     with_items:
        ‐ { src: "./httpd.conf", dest: "/etc/httpd/conf/", mode: "0644" }
        ‐ { src: "./upload_file.php", dest: "/var/www/html/", mode: "0600" }

playbook handlers

---

【什么是handlers?】

handler 用来执行某些条件下的任务，比如当配置文件发生变化的时候，通过notify触发handler去重启服务。

在saltstack中也有类似的触发器，写法相对Ansible简单，只需要watch，配置文件即可。

---

【实践案例】

[root@m01 ~]# cat handler.yml
‐ hosts: web_group
  vars:
    ‐ http_port: 8080
  tasks:
    ‐ name: Install Http Server
      yum:
        name: httpd
        state: present
    ‐ name: config httpd server
      template:
        src: ./httpd.j2
        dest: /etc/httpd/conf
    notify:
      ‐ Restart Httpd Server
      ‐ Restart PHP Server
    ‐ name: start httpd server
      service:
        name:httpd
        state: started
        enabled: yes

handlers:
  ‐ name: Restart Httpd Server
    systemd:
      name: httpd
      state: restarted

  ‐ name: Restart PHP Server
    systemd:
      name: php‐fpm
      state: restarted

练习：多个nginx配置文件的推送及触发器

---

注意：

1.无论多少个task通知了相同的handlers，handlers仅会在所有tasks结束后运行一次。

2.Handlers只有在其所在的任务被执行时，才会被运行；如果一个任务中定义了notify调用Handlers，但是由于条件判

断等原因，该任务未被执行，那么Handlers同样不会被执行。

3.Handlers只会在每一个play的末尾运行一次；如果想在一个playbook中间运行Handlers，则需要使用meta模块来实

现。例如： -meta: flush_handlers。

4.如果一个play在运行到调用Handlers的语句之前失败了，那么这个Handlers将不会被执行。我们可以使用meta模块

的–force-handlers选项来强制执行Handlers，即使Handlers所在的play中途运行失败也能执行。

5.不能使用handlers替代tasks

---

playbook任务标签

默认情况下，Ansible在执行一个playbook时，会执行playbook中定义的所有任务，Ansible的标签(tag)功能可以给单 独任务甚至整个playbook打上标签，然后利用这些标签来指定要运行playbook中的个别任务，或不执行指定的任务。

---

打标签的方式】

1.对一个task打一个标签

2.对一个task打多个标签

3.对多个task打一个标签

---

【打完标签如何使用】

-t:执行指定的tag标签任务

–skip-tags:执行–skip-tags之外的标签任务

---

【使用-t指定tag】

[root@m01 m01]# cat tag.yml
‐ hosts: web_group
  vars:
    ‐ http_port: 8080
  tasks:
  ‐ name: Install Http Server
    yum:
      name: httpd
      state: present
    tags:
      ‐ install_httpd
      ‐ httpd_server
  ‐ name: configure httpd server
    template:
      src: ./httpd.j2
      dest: /etc/httpd/conf/httpd.conf
    notify: Restart Httpd Server
    tags:
      ‐ config_httpd
      ‐ httpd_server

  ‐ name: start httpd server
    service:
      name: httpd
      state: started
      enabled: yes
     tags: service_httpd

handlers:
  ‐ name: Restart Httpd Server
    systemd:
      name: httpd
      state: restarted

[root@m01 m01]# ansible‐playbook tag.yml ‐‐list‐tags
[root@m01 m01]# ansible‐playbook tag.yml ‐t httpd_server
[root@m01 m01]# ansible‐playbook tag.yml ‐t install_httpd,confiure_httpd
[root@m01 m01]# ansible‐playbook tag.yml ‐‐skip‐tags httpd_server

playbook文件复用

在之前写playbook的过程中，我们发现，写多个playbook没有办法，一键执行，这样我们还要单个playbook挨个去执行，很鸡肋。所以在playbook中有一个功能，叫做 include 用来动态调用task任务列表

调用task： include_tasks

调用整个task文件： include （新版本：import_playbook）

在saltstack中，叫做 top file 入口文件。

示例一：

[root@m01 m01]# cat task.yml
‐ hosts: web_group
  vars:
    ‐ http_port: 8080
  tasks:
    ‐ include_tasks: task_install.yml
    ‐ include_tasks: task_configure.yml
    ‐ include_tasks: task_start.yml
  handlers:
    ‐ name: Restart Httpd Server
    systemd:
      name: httpd
      state: restarted

[root@m01 m01]# cat task_install.yml
‐ name: Install Http Server
  yum:
    name: httpd
    state: present

[root@m01 m01]# cat task_configure.yml
‐ name: configure httpd server
  template:
    src: ./httpd.j2
    dest: /etc/httpd/conf/httpd.conf
  notify: Restart Httpd Server

[root@m01 m01]# cat task_start.yml
‐ name: start httpd server
  service:
    name: httpd
    state: started
    enabled: yes 

示例二：

‐ include: httpd.yml
‐ include: nfs.yml
‐ include: rsync.yml

示例三：

‐ import_playbook: httpd.yml
‐ import_playbook: nfs.yml
‐ import_playbook: rsync.yml

playbook忽略错误

默认playbook会检测task执行的返回状态，如果遇到错误则会立即终止playbook的后续task执行，然鹅有些时候 playbook即使执行错误了也要让其继续执行。

加入参数：ignore_errors:yes 忽略错误

[root@m01 ~]# cat ignore.yml
‐‐‐
‐ hosts: web_group
  tasks:
    ‐ name: Ignore False
    command: /bin/false
    ignore_errors: yes
  ‐ name: touch new file
    file:
      path: /tmp/kirin.txt
      state: touch

playbook错误处理

如上所述，当task执行失败时，playbook将不再继续执行，包括如果在task中设置了handler也不会被执行。 但是我们可以采取强制措施…

---

【强制调用handler】

[root@m01 ~]# cat handler.yml
‐ hosts: web_group
  vars:
    ‐ http_port: 8080
  force_handlers: yes
  tasks:

    ‐ name: config httpd server
      template:
        src: ./httpd.j2
        dest: /etc/httpd/conf
      notify:
        ‐ Restart Httpd Server
        ‐ Restart PHP Server

    ‐ name: Install Http Server
      yum:
        name: htttpd
        state: present

    ‐ name: start httpd server
      service:
        name:httpd
        state: started
        enabled: yes

  handlers:
    ‐ name: Restart Httpd Server
      systemd:
        name: httpd
        state: restarted

    ‐ name: Restart PHP Server
      systemd:
        name: php‐fpm
        state: restarted

---

【抑制changed】

[root@m01 ~]# cat handler.yml
‐ hosts: web_group
  vars:
    ‐ http_port: 8080
  force_handlers: yes
  tasks:
    ‐ name: shell
      shell: netstat ‐lntup|grep httpd
      register: check_httpd
      changed_when: false

  ‐ name: debug
    debug: msg={{ check_httpd.stdout.lines }}

[root@m01 project2]# cat changed_when.yml
‐ hosts: webservers
  vars:
    ‐ http_port: 8080
  tasks:
    ‐ name: configure httpd server
      template:
        src: ./httpd.j2
        dest: /etc/httpd/conf/httpd.conf
      notify: Restart Httpd Server

    ‐ name: Check HTTPD
      shell: /usr/sbin/httpd ‐t
      register: httpd_check
      changed_when:
        ‐ httpd_check.stdout.find('OK')
        ‐ false

    ‐ name: start httpd server
      service:
        name: httpd
        state: started
        enabled: yes

  handlers:
    ‐ name: Restart Httpd Server
      systemd:
        name: httpd
        state: restarted