Hi,
We are currently asking ourselves in Team in which order handlers are executed from roles. We have several roles in a playbook with several handlers. In some playbooks, the handlers are executed in alphabetical order of the roles, but not in all playbooks.
We can’t find anything in the documentation either: Handlers: running operations on change — Ansible Community Documentation
They are executed based on the order they are defined in. Here’s a relevant snippet from the documentation:
In the above example, the handlers are executed on task change in the following order:
Restart memcached,Restart apache. Handlers are executed in the order they are defined in thehandlerssection, not in the order listed in thenotifystatement.
This is the Roles Part of our Playbook:
roles:
- role: elasticsearch-apikey
- role: haproxy
- role: executable-jar
This is the Result:
RUNNING HANDLER [elasticsearch-apikey : esapikey_invalidate_keys] **************
Tuesday 30 July 2024 17:04:14 +0200 (0:00:01.281) 0:00:34.533 **********
ok: [server11-dev]
RUNNING HANDLER [executable-jar : Executable_jar is restarted] *****************
Tuesday 30 July 2024 17:04:16 +0200 (0:00:01.590) 0:00:36.123 **********
changed: [server11-dev]
RUNNING HANDLER [executable-jar : Executable_jar is alive] *********************
Tuesday 30 July 2024 17:04:16 +0200 (0:00:00.518) 0:00:36.641 **********
ok: [server11-dev]
RUNNING HANDLER [haproxy : Haproxy Daemon reload] ******************************
Tuesday 30 July 2024 17:04:23 +0200 (0:00:07.031) 0:00:43.673 **********
ok: [server11-dev]
RUNNING HANDLER [haproxy : Haproxy started] ************************************
Tuesday 30 July 2024 17:04:24 +0200 (0:00:00.850) 0:00:44.523 **********
ok: [server11-dev]
RUNNING HANDLER [haproxy : Haproxy restarted] **********************************
Tuesday 30 July 2024 17:04:25 +0200 (0:00:00.499) 0:00:45.023 **********
changed: [server11-dev]
RUNNING HANDLER [haproxy : Haproxy reloaded] ***********************************
Tuesday 30 July 2024 17:04:26 +0200 (0:00:00.946) 0:00:45.970 **********
changed: [server11-dev]
But this is not the Order we defined!
Can you include the relevant handlers files so I can see the order they are defined in to try to reproduce the issue? Can you share the version of ansible-core you’re using too?
/roles/elasticsearch-apikey/handlers/main.yml:
- name: esapikey_invalidate_keys
ansible.builtin.uri:
url: "{{ esapikey_url }}/_security/api_key"
/roles/executable-jar/handlers/main.yml:
- name: Executable_jar is restarted
ansible.builtin.service:
name: executable-jar
state: restarted
enabled: true
become: true
listen: executable_jar_restarted
- name: Executable_jar is alive
ansible.builtin.uri:
url: "{{ executable_jar_alive_url }}"
status_code: 200
register: result
until: result.status == 200
retries: 60
delay: 1
tags: config
listen: executable_jar_alive
when:
- not ansible_check_mode
- executable_jar_alive_check
/roles/haproxy/handlers/main.yml:
- name: Haproxy Daemon reload
ansible.builtin.systemd:
daemon_reload: true
become: true
listen: Haproxy_daemon_reload
- name: Haproxy started
ansible.builtin.service:
name: haproxy
state: started
enabled: true
become: true
listen: Haproxy_started
- name: Haproxy restarted
ansible.builtin.service:
name: haproxy
state: restarted
enabled: true
become: true
listen: Haproxy_restarted
- name: Haproxy reloaded
ansible.builtin.service:
name: haproxy
state: reloaded
enabled: true
become: true
listen: Haproxy_reloaded
The handlers file in haproxy defines the handlers in this order:
The result you shared matches the order, I think.
I’m not sure where the handlers are notified, or if this could be a point of misunderstanding, but the notify order is not the definition-order. Here’s the relevant bit from the documentation:
Handlers are executed in the order they are defined in the
handlerssection, not in the order listed in thenotifystatement.
If I’m missing something, could you share the expected result?
First, handlers, no matter where defined, are attached to the play, so while a role can provide handlers they are always PLAY level handlers. The order of execution depends on the order in which they were added/defined to the play. This can get tricky with dependent roles and conflicting names, but should still hold true.
We have no dependency’s in our Roles. If I understand you correctly, all (handlers in the) roles should now be executed in the same order as listed under “roles:”, but currently they are executed in alphabetical order.
Is it possible to debug the order of handlers?
We dont want to flush the handlers at the end of each Role, just to ensure they get executed in the right order.
We have 3 Roles with Handlers:
roles:
- role: Role_A
- role: Role_C
- role: Role_B
and I expect these execution Order of the handlers:
- Role_A_Handler_1
- Role_A_Handler_2
- Role_C_Handler_1
- Role_C_Handler_2
- Role_B_Handler_1
- Role_B_Handler_2
but I get:
- Role_A_Handler_1
- Role_A_Handler_2
- Role_B_Handler_1
- Role_B_Handler_2
- Role_C_Handler_1
- Role_C_Handler_2
And what is the order of handler notifies? Same as role order? Do you notify a handler in one role from some other role?
No, we have no cross roles notify. All handler get notified in there own Role.
Notification should not influence execution order, if the above is true, this is a bug. I would submit to github with a simple reproducer.
I created a simple reproducer, but everything runs just fine - no Bug!
Now we have to test our Ansible Setup and all used Versions for the cause of the problem 
I found our Problem. We have used the same Role more than once in the same Playbook.
roles:
- role: role_2
- role: role_1
- role: role_3
- role: role_1
Handler Executon Order:
So it works as expected, role1 handlers get ‘redefined’ so the first definition is masked by the latter, accounting for the change in order.
This topic was automatically closed 30 days after the last reply. New replies are no longer allowed.