请参阅Ansible 2.5中新增的service_facts模块。

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

当然，我也可以检查 Package 器脚本是否存在于/etc/init. d中。

- 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

我修改了Florian's answer，只使用service命令的返回代码（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

如果“服务”模块能够处理“无法识别的服务”错误，那就太好了。
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“未识别的服务”时接受退出代码0
• 如果退出代码为0，则该服务已安装（已停止或正在运行）

systemd（from Jakuje）的另一种方法：

- name: Check if cups-browsed service exists
  command: systemctl cat cups-browsed
  check_mode: no
  register: cups_browsed_exists
  changed_when: False
  failed_when: cups_browsed_exists.rc not in [0, 1]

- name: Stop cups-browsed service
  systemd:
    name: cups-browsed
    state: stopped 
  when: cups_browsed_exists.rc == 0

基于@Maciej对RedHat 8的回答，并将其与对它的评论相结合。
这就是我如何设法停止Celery只有当它已经安装：

- name: Populate service facts
  service_facts:
- debug:
    msg: httpd installed!
  when: ansible_facts.services['httpd.service'] is defined

- name: Stop celery.service
  service:
    name: celery.service
    state: stopped
    enabled: true
  when: ansible_facts.services['celery.service'] is defined

您可以删除调试语句--它只是用来确认ansible_factors是否正常工作。

这种仅使用服务模块的方式对我们很有效：

- name: Disable *service_name*
  service:
    name: *service_name*
    enabled: no
    state: stopped
  register: service_command_output
  failed_when: >
    service_command_output|failed
    and 'unrecognized service' not in service_command_output.msg
    and 'Could not find the requested service' not in service_command_output.msg

我的几分钱。与上面相同的方法，但对kubernetes

检查kublete服务是否正在运行

- name: "Obtain state of kublet service"
  command: systemctl status kubelet.service
  register: kubelet_status
  failed_when: kubelet_status.rc > 3

如果kublet服务未运行，则显示调试消息

- debug:
    msg: "{{ kubelet_status.stdout }}"
  when: "'running' not in kubelet_status.stdout"

从Ansible 2.5开始，您可以使用service_facts模块。但是您需要知道输出是服务的真实名称，如docker.service或somthing@.service。因此，您有不同的选项，如：

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

或者，您可以搜索以服务名称开头的字符串;这要可靠得多，因为服务名称在不同的发行版之间是不同的：

- name: Populate service facts
  service_facts:
- debug:
    msg: Docker installed!
  when: "services.keys()|list|select('search', '^docker')|length >0"