# cross-role notifications **URL:** \ **Category:** Ansible Project\ **Created:** [February 12, 2017, 4:56pm UTC](https://forum.ansible.com/t/cross-role-notifications/23713 "2017-02-12T16:56:06Z")\ **Posts on this page:** 9\ **Page:** 1
**Author:** ![Michael\_Stroder](https://avatars.discourse-cdn.com/v4/letter/m/7ea924/32.png) [@Michael\_Stroder](https://forum.ansible.com/u/Michael_Stroder)\ **Post date:** [February 12, 2017, 4:56pm UTC](https://forum.ansible.com/t/cross-role-notifications/23713/1 "2017-02-12T16:56:06Z")
HI! In the spirit of encapsulation I've implemented different roles installing different components. Now the roles also ensure that OS packages (.deb or .rpm) and specific Python modules (pip install) are installed and automagically updated. (I don't want to start a debate whether one wants automatic upgrades or not. I simply want that.) Within the roles OS package / PIP updates will notify the approriate handlers and services managed within the same role will be restarted. But some updates might also require restart of a service managed in a subsequently invoked role which does not receive the notifications. (In puppet I'd simply \_subscribe\_ to the resource to "pull" the notification.) How to handle this case in ansible? Ciao, Michael. ---
**Author:** ![Kai\_Stian\_Olstad](https://avatars.discourse-cdn.com/v4/letter/k/e19adc/32.png) [@Kai\_Stian\_Olstad](https://forum.ansible.com/u/Kai_Stian_Olstad)\ **Post date:** [February 12, 2017, 5:39pm UTC](https://forum.ansible.com/t/cross-role-notifications/23713/2 "2017-02-12T17:39:39Z")
Ansible doesn't have something like subscribe so you'll have to use notify. But you can notify a handler in another role since they are global. ---
**Author:** ![Michael\_Stroder](https://avatars.discourse-cdn.com/v4/letter/m/7ea924/32.png) [@Michael\_Stroder](https://forum.ansible.com/u/Michael_Stroder)\ **Post date:** [February 12, 2017, 5:47pm UTC](https://forum.ansible.com/t/cross-role-notifications/23713/3 "2017-02-12T17:47:21Z")
Kai Stian Olstad wrote: ---
**Author:** ![Johannes\_Kastl](https://avatars.discourse-cdn.com/v4/letter/j/bbe5ce/32.png) [@Johannes\_Kastl](https://forum.ansible.com/u/Johannes_Kastl)\ **Post date:** [February 12, 2017, 5:53pm UTC](https://forum.ansible.com/t/cross-role-notifications/23713/4 "2017-02-12T17:53:24Z")
AFAIK the role design is built so you could reuse roles in more than one place. E.g. create a role that just installs nginx, and is set as a dependency for the roles creating a webserver with nginx, a load balancer with nginx, etc. This way you would have to put together the installation steps in only one role, not in multiple roles. The solution to your notify dilemma maybe a delegate\_to in the handler. Or duplicating the handler in your role. Maybe we could help better if we knew what problem you are solving, or what applications need your to call your handler in another role... Johannes ---
**Author:** ![Kai\_Stian\_Olstad](https://avatars.discourse-cdn.com/v4/letter/k/e19adc/32.png) [@Kai\_Stian\_Olstad](https://forum.ansible.com/u/Kai_Stian_Olstad)\ **Post date:** [February 12, 2017, 5:57pm UTC](https://forum.ansible.com/t/cross-role-notifications/23713/5 "2017-02-12T17:57:47Z")
The same challenge you have with subscribe in Puppet, you'll need to use the other resources name. You can always create the handler in the role so you don't need to use the other roles handler, that's what I do to make them independent. ---
**Author:** ![Michael\_Stroder](https://avatars.discourse-cdn.com/v4/letter/m/7ea924/32.png) [@Michael\_Stroder](https://forum.ansible.com/u/Michael_Stroder)\ **Post date:** [February 12, 2017, 6:15pm UTC](https://forum.ansible.com/t/cross-role-notifications/23713/6 "2017-02-12T18:15:40Z")
Kai Stian Olstad wrote: > > Kai Stian Olstad wrote: > > > > > > But some updates might also require restart of a service managed in a subsequently > > > > invoked role which does not receive the notifications. > > > > (In puppet I'd simply \_subscribe\_ to the resource to "pull" the notification.) > > > > > > > > How to handle this case in ansible? > > > > > > Ansible doesn't have something like subscribe so you'll have to use notify. > > > But you can notify a handler in another role since they are global. > > > > But then a role has to know the handler names in the other role which somewhats > > contradicts the concept of modular design. > > The same challenge you have with subscribe in Puppet, you'll need to use the other > resources name. Yes. But the resource name would be the OS package's name which the relevant roles would know anyway. (I'm not a puppet fan though.) > You can always create the handler in the role so you don't need to use the other roles > handler, that's what I do to make them independent. I'll try explain better. Assume a play invoking two roles A and B: role A   - installs pkg1 with notifying "restart srv1" in case of a package update   - enables and initially starts service srv1   - has handler "restart srv1" which restarts service srv1 role B   - installs \*pkg1\* with notifying "restart srv2" in case of a package update   - enables and initially starts service srv2   - has handler "restart srv2" which restarts service srv2 When role A gets played the handler "restart srv1" will receive the notification of pkg1 update but in role B there will be no such pkg1 update anymore and thus no notification to handler "restart srv2" and therefore srv2 continous to run based on outdated software (which I'd like to avoid). Or can I have handlers with same name "restart srv1 and srv2" in more than role and all gets notified? Ciao, Michael. ---
**Author:** ![Michael\_Stroder](https://avatars.discourse-cdn.com/v4/letter/m/7ea924/32.png) [@Michael\_Stroder](https://forum.ansible.com/u/Michael_Stroder)\ **Post date:** [February 12, 2017, 6:19pm UTC](https://forum.ansible.com/t/cross-role-notifications/23713/7 "2017-02-12T18:19:00Z")
Johannes Kastl wrote: > > But then a role has to know the handler names in the other role > > which somewhats contradicts the concept of modular design. > > AFAIK the role design is built so you could reuse roles in more than > one place. E.g. create a role that just installs nginx, and is set as > a dependency for the roles creating a webserver with nginx, a load > balancer with nginx, etc. This way you would have to put together the > installation steps in only one role, not in multiple roles. Yes I know. But the world is a bit more complicated. Two different roles could require and thus update the same OS packages (in my case Python modules). Completely \*different\* services managed in different roles would have to be restarted. > The solution to your notify dilemma maybe a delegate\_to in the > handler. Or duplicating the handler in your role. > > Maybe we could help better if we knew what problem you are solving, or > what applications need your to call your handler in another role... See also my other recent posting. Ciao, Michael. ---
**Author:** ![Kai\_Stian\_Olstad](https://avatars.discourse-cdn.com/v4/letter/k/e19adc/32.png) [@Kai\_Stian\_Olstad](https://forum.ansible.com/u/Kai_Stian_Olstad)\ **Post date:** [February 12, 2017, 7:06pm UTC](https://forum.ansible.com/t/cross-role-notifications/23713/8 "2017-02-12T19:06:56Z")
If you have handlers with the same name only one of them will be notified (see the note in the link bellow). But in Ansible 2.2 notify has a listen: feature. If you add listen: 'restart srv" to the handlers "restart srv1" and "restart srv2", then you can use notify: 'restart srv" instead and both of them will get notified. And if you remove role A or role B it will still work. Read more about listen: here [https://docs.ansible.com/ansible/playbooks\_intro.html#handlers-running-operations-on-change](https://docs.ansible.com/ansible/playbooks_intro.html#handlers-running-operations-on-change) ---
**Author:** ![Michael\_Stroder](https://avatars.discourse-cdn.com/v4/letter/m/7ea924/32.png) [@Michael\_Stroder](https://forum.ansible.com/u/Michael_Stroder)\ **Post date:** [February 12, 2017, 7:35pm UTC](https://forum.ansible.com/t/cross-role-notifications/23713/9 "2017-02-12T19:35:21Z")
Kai Stian Olstad wrote: > But in Ansible 2.2 notify has a listen: feature. > > If you add listen: 'restart srv" to the handlers "restart srv1" and "restart srv2", > then you can use notify: 'restart srv" instead and both of them will get notified. > And if you remove role A or role B it will still work. Thanks for this hint! I'll give it a try. Ciao, Michael.