Docsite: fix user_guide/playbooks_handlers (#71770)

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Andrew Klychkov 2020-09-17 17:19:24 +03:00 committed by GitHub
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@ -14,49 +14,54 @@ Handler example
This playbook, ``verify-apache.yml``, contains a single play with a handler::
---
- name: verify apache installation
- name: Verify apache installation
hosts: webservers
vars:
http_port: 80
max_clients: 200
remote_user: root
tasks:
- name: ensure apache is at the latest version
yum:
- name: Ensure apache is at the latest version
ansible.builtin.yum:
name: httpd
state: latest
- name: write the apache config file
template:
- name: Write the apache config file
ansible.builtin.template:
src: /srv/httpd.j2
dest: /etc/httpd.conf
notify:
- restart apache
- name: ensure apache is running
service:
- Restart apache
- name: Ensure apache is running
ansible.builtin.service:
name: httpd
state: started
handlers:
- name: restart apache
service:
- name: Restart apache
ansible.builtin.service:
name: httpd
state: restarted
In this example playbook, the second task notifies the handler. A single task can notify more than one handler::
- name: template configuration file
template:
- name: Template configuration file
ansible.builtin.template:
src: template.j2
dest: /etc/foo.conf
notify:
- restart memcached
- restart apache
- Restart memcached
- Restart apache
handlers:
- name: restart memcached
service:
- name: Restart memcached
ansible.builtin.service:
name: memcached
state: restarted
- name: restart apache
service:
- name: Restart apache
ansible.builtin.service:
name: apache
state: restarted
@ -68,9 +73,14 @@ By default, handlers run after all the tasks in a particular play have been comp
If you need handlers to run before the end of the play, add a task to flush them using the :ref:`meta module <meta_module>`, which executes Ansible actions::
tasks:
- shell: some tasks go here
- meta: flush_handlers
- shell: some other tasks
- name: Some tasks go here
ansible.builtin.shell: ...
- name: Flush handlers
meta: flush_handlers
- name: Some other tasks
ansible.builtin.shell: ...
The ``meta: flush_handlers`` task triggers any handlers that have been notified at that point in the play.
@ -80,8 +90,8 @@ Using variables with handlers
You may want your Ansible handlers to use variables. For example, if the name of a service varies slightly by distribution, you want your output to show the exact name of the restarted service for each target machine. Avoid placing variables in the name of the handler. Since handler names are templated early on, Ansible may not have a value available for a handler name like this::
handlers:
# this handler name may cause your play to fail!
- name: restart "{{ web_service_name }}"
# This handler name may cause your play to fail!
- name: Restart "{{ web_service_name }}"
If the variable used in the handler name is not available, the entire play fails. Changing that variable mid-play **will not** result in newly created handler.
@ -94,28 +104,29 @@ Instead, place variables in the task parameters of your handler. You can load th
include_vars: "{{ ansible_facts.distribution }}.yml"
handlers:
- name: restart web service
service:
- name: Restart web service
ansible.builtin.service:
name: "{{ web_service_name | default('httpd') }}"
state: restarted
Handlers can also "listen" to generic topics, and tasks can notify those topics as follows::
handlers:
- name: restart memcached
service:
- name: Restart memcached
ansible.builtin.service:
name: memcached
state: restarted
listen: "restart web services"
- name: restart apache
service:
- name: Restart apache
ansible.builtin.service:
name: apache
state: restarted
listen: "restart web services"
tasks:
- name: restart everything
command: echo "this task will restart the web services"
- name: Restart everything
ansible.builtin.command: echo "this task will restart the web services"
notify: "restart web services"
This use makes it much easier to trigger multiple handlers. It also decouples handlers from their names,
@ -132,6 +143,6 @@ a shared source like Galaxy).
When using handlers within roles, note that:
* handlers notified within ``pre_tasks``, ``tasks``, and ``post_tasks`` sections are automatically flushed in the end of section where they were notified.
* handlers notified within ``roles`` section are automatically flushed in the end of ``tasks`` section, but before any ``tasks`` handlers.
* handlers notified within ``pre_tasks``, ``tasks``, and ``post_tasks`` sections are automatically flushed at the end of section where they were notified.
* handlers notified within ``roles`` section are automatically flushed at the end of ``tasks`` section, but before any ``tasks`` handlers.
* handlers are play scoped and as such can be used outside of the role they are defined in.