检查Ansible是否存在服务

Question

我有一个Ansible手册,用于将Java应用程序部署为init.d守护程序.

作为Ansible和Linux的初学者,我很难根据主机的状态有条件地在主机上执行任务.

也就是说,我有一些主机已经提供服务,并且在我做任何其他事情之前我想要停止它.然后可能会有新主机,但尚未提供服务.所以我不能简单地使用service: name={{service_name}} state=stopped,因为这将在新主机上失败.

我怎么能做到这一点？这是我到目前为止所拥有的:

  - name: Check if Service Exists
    shell: "if chkconfig --list | grep -q my_service;   then echo true;   else echo false; fi;"
    register: service_exists

# This should only execute on hosts where the service is present
  - name: Stop Service
    service: name={{service_name}} state=stopped
    when: service_exists
    register: service_stopped

# This too
  - name: Remove Old App Folder
    command: rm -rf {{app_target_folder}}
    when: service_exists

# This should be executed on all hosts, but only after the service has stopped, if it was present
  - name: Unpack App Archive
    unarchive: src=../target/{{app_tar_name}} dest=/opt

Answer 1

当然我也可以检查/etc/init.d中是否存在包装脚本.所以这就是我最终的结果:

  - name: Check if Service Exists
    stat: path=/etc/init.d/{{service_name}}
    register: service_status

  - name: Stop Service
    service: name={{service_name}} state=stopped
    when: service_status.stat.exists
    register: service_stopped

Answer 2

请参阅service_factsAnsible 2.5中的新模块.

- name: Populate service facts
  service_facts:
- debug:
    msg: Docker installed!
  when: "'docker' in services"

Answer 3

如果"服务"模块可以处理"无法识别的服务"错误,那将是很好的.

这是我的方法,使用service命令而不是检查init脚本:

- name: check for apache
  shell: "service apache2 status"
  register: _svc_apache
  failed_when: >
    _svc_apache.rc != 0 and ("unrecognized service" not in _svc_apache.stderr)

- name: disable apache
  service: name=apache2 state=stopped enabled=no
  when: "_svc_apache.rc == 0"

• 检查"服务状态"的退出代码,并在输出包含"无法识别的服务"时接受退出代码0
• 如果退出代码为0,则安装该服务(已停止或正在运行)

Answer 4

我修改了Florian的答案，使其仅使用service命令的返回码（这在Mint 18.2上有效）

- name: Check if Logstash service exist
  shell: service logstash status 
  register: logstash_status
  failed_when: not(logstash_status.rc == 3 or logstash_status.rc == 0)

- name: Check if Logstash service exist
  service:
    name: logstash
    state: stopped 
  when: logstash_status.rc == 0