使用 Ansible 检查服务是否存在

Question

我有一个 Ansible playbook，用于将 Java 应用程序部署为 init.d 守护进程。

作为 Ansible 和 Linux 的初学者，我无法根据主机的状态有条件地在主机上执行任务。

也就是说，我有一些主机已经存在服务并且正在运行，我想在做任何其他事情之前停止它。然后可能会有新的主机，它们还没有服务。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。

我怎样才能做到这一点？到目前为止，这是我所拥有的：

  - 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

查看 service_facts 模块，Ansible 2.5 中的新模块。

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

Answer 2

当然，我也可以只检查包装脚本是否存在于 /etc/init.d 中。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 3

我将Florian's answer 修改为仅使用service 命令的返回码（这适用于Mint 18.2）

- 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

Answer 4

如果“服务”模块可以处理“无法识别的服务”错误，那就太好了。

这是我的方法，使用service 命令而不是检查初始化脚本：

- 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，当输出包含“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（停止或运行）

Answer 5

systemd 的另一种方法 (from Jakuje)：

- 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

Answer 6

这种只使用服务模块的方式对我们有用：

- 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

Answer 7

我的几分钱。与上述方法相同，但适用于 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"