# exec vs. notify - An improvement proposal **URL:** \ **Category:** Ansible Project\ **Created:** [April 29, 2013, 6:25am UTC](https://forum.ansible.com/t/exec-vs-notify-an-improvement-proposal/12734 "2013-04-29T06:25:09Z")\ **Posts on this page:** 11\ **Page:** 1
**Author:** ![James\_Mills](https://avatars.discourse-cdn.com/v4/letter/j/d78d45/32.png) [@James\_Mills](https://forum.ansible.com/u/James_Mills)\ **Post date:** [April 29, 2013, 6:25am UTC](https://forum.ansible.com/t/exec-vs-notify-an-improvement-proposal/12734/1 "2013-04-29T06:25:09Z")
Hi all, I’ve run into a situation that for me demands an improvement to “notify” or an additional parameter that you can attach to tasks. e.g: - name: Build/Install foo action: command make install exec: refresh ld cache Where “refresh ld cache” is defined as: - name: refresh ld cache action: command /sbin/ldconfig Basically as I understand it, notify has a many:1 relationship meaning that no matter how many tasks refer to a “handler”, it is only executed once. More over, it is only executed at the end of a play. This works for the use-case(s) of: - Restart services (e.g: Apache) - Reboot and possibly some others… But does not work in general for the use case of: “After this task has successfully completed” “Do this task right now” I’m not sure if notify could be improved to handle thie use-case without breaking existing user-cases. But it sounds ot me l ike we need an “exec \” that I described above. Has anyone else ran into this as well? What are your thoughts? Right now, I’m solving this problem by doing the following in my roles: - include: …/…/common/tasks/ldconfig.yml Where ldconfig.yml looks like: ---
**Author:** ![kahlil.hodgson](https://avatars.discourse-cdn.com/v4/letter/k/b9bd4f/32.png) [@kahlil.hodgson](https://forum.ansible.com/u/kahlil.hodgson)\ **Post date:** [April 29, 2013, 6:53am UTC](https://forum.ansible.com/t/exec-vs-notify-an-improvement-proposal/12734/2 "2013-04-29T06:53:26Z")
It sounds like you are doing it right to me. You have an ordered list of dependent tasks. If one task fails, don't continue because it'll likely bork you system, unless you know for sure its okay, in which case set 'ignore\_errors'. For more fine grained control, you might want to add something like a     register: foo for the first task and a     when: foo.changed to the second task (or appropriate variations). K ---
**Author:** ![Serge\_van\_Ginderacht](https://avatars.discourse-cdn.com/v4/letter/s/b782af/32.png) [@Serge\_van\_Ginderacht](https://forum.ansible.com/u/Serge_van_Ginderacht)\ **Post date:** [April 29, 2013, 6:58am UTC](https://forum.ansible.com/t/exec-vs-notify-an-improvement-proposal/12734/3 "2013-04-29T06:58:33Z")
​You should do this with a   register: task​ then putting your exec in a second task with when: task.changed     (1.2 syntax) Serge ---
**Author:** ![Michael\_DeHaan2](https://avatars.discourse-cdn.com/v4/letter/m/da6949/32.png) [@Michael\_DeHaan2](https://forum.ansible.com/u/Michael_DeHaan2)\ **Post date:** [April 29, 2013, 12:25pm UTC](https://forum.ansible.com/t/exec-vs-notify-an-improvement-proposal/12734/4 "2013-04-29T12:25:02Z")
Correct. Under 1.1, which does not have the benefit of cleaned up variables, it looks roughly like this: when\_boolean: ${task.changed} ---
**Author:** ![James\_Mills](https://avatars.discourse-cdn.com/v4/letter/j/d78d45/32.png) [@James\_Mills](https://forum.ansible.com/u/James_Mills)\ **Post date:** [April 29, 2013, 12:29pm UTC](https://forum.ansible.com/t/exec-vs-notify-an-improvement-proposal/12734/5 "2013-04-29T12:29:50Z")
Thank you both for your responses. Whilst I understand I can “register a variable” and “conditionally perform a task” I don’t find this particularly very intuitive. It makes far more sense to me (except that notify isn’t designed this way) to “call a task” (i.e: notify) when one taks has successfully completed. think of an event rather than a conditional execution. - name: foo action command foo register: foo - name: on foo action: foo\_callback when: foo.changed This isn’t particular intuitive. But this is: - name: foo action: command foo notify: on foo - name: on foo action: foo\_callback Except notify isn’t designed like this 😕 cheers James ---
**Author:** ![Michael\_DeHaan2](https://avatars.discourse-cdn.com/v4/letter/m/da6949/32.png) [@Michael\_DeHaan2](https://forum.ansible.com/u/Michael_DeHaan2)\ **Post date:** [April 29, 2013, 2:13pm UTC](https://forum.ansible.com/t/exec-vs-notify-an-improvement-proposal/12734/6 "2013-04-29T14:13:19Z")
Understood. One of the the challenges of open source is that things intuitive to one person aren’t intuitive to everyone. We will be sticking with “when: foo.changed” as that allows you to keep the task at _exactly the point where it will run_ in the task list, which makes things clear, and also allows stuff like: when: foo.changed and bar.changed and x \> 3 etc We’ve got thousands of people using things this way and they’ve been ok with it so far. While I am open to adding new language constructs, we add them rather conservatively, as we aim to support things indefinitely. ---
**Author:** ![James\_Mills](https://avatars.discourse-cdn.com/v4/letter/j/d78d45/32.png) [@James\_Mills](https://forum.ansible.com/u/James_Mills)\ **Post date:** [April 30, 2013, 1:51am UTC](https://forum.ansible.com/t/exec-vs-notify-an-improvement-proposal/12734/7 "2013-04-30T01:51:40Z")
I have ried this using register but I’m unable to make this work. See this snippet: - name: Build/Install GDAL action: command make install chdir=/usr/local/src/gdal-$gdal\_version creates=/usr/local/bin/gdal-config register: last\_result - include: …/…/common/tasks/ldconfig.yml when: last\_result.changed This cannot work because of the “creates” condition applied to the build task. the condition “last\_result.changed” failed because it’s never defined. I’m not sure how to solve this. cheers James ---
**Author:** ![kahlil.hodgson](https://avatars.discourse-cdn.com/v4/letter/k/b9bd4f/32.png) [@kahlil.hodgson](https://forum.ansible.com/u/kahlil.hodgson)\ **Post date:** [April 30, 2013, 2:18am UTC](https://forum.ansible.com/t/exec-vs-notify-an-improvement-proposal/12734/8 "2013-04-30T02:18:06Z")
I often find, with the boolean conditional, I have to do things like when: last\_result is defined and last\_result.changed Or variations. Hope this helps. K ---
**Author:** ![Yves\_Dorfsman](https://avatars.discourse-cdn.com/v4/letter/y/9de0a6/32.png) [@Yves\_Dorfsman](https://forum.ansible.com/u/Yves_Dorfsman)\ **Post date:** [April 30, 2013, 5:05am UTC](https://forum.ansible.com/t/exec-vs-notify-an-improvement-proposal/12734/9 "2013-04-30T05:05:30Z")
You used to be able to use "when\_set: last\_result", but the new documentation only shows example of "when". ---
**Author:** ![Michael\_DeHaan](https://avatars.discourse-cdn.com/v4/letter/m/c4cdca/32.png) [@Michael\_DeHaan](https://forum.ansible.com/u/Michael_DeHaan)\ **Post date:** [April 30, 2013, 12:31pm UTC](https://forum.ansible.com/t/exec-vs-notify-an-improvement-proposal/12734/10 "2013-04-30T12:31:57Z")
“This cannot work because of the “creates” condition applied to the build task. the condition “last\_result.changed” failed because it’s never defined.” Ok, this is an easy one. I need to make the “skipped” data that returns from the command module also return “changed=False”. I will make this happen. ---
**Author:** ![Michael\_DeHaan](https://avatars.discourse-cdn.com/v4/letter/m/c4cdca/32.png) [@Michael\_DeHaan](https://forum.ansible.com/u/Michael_DeHaan)\ **Post date:** [April 30, 2013, 12:36pm UTC](https://forum.ansible.com/t/exec-vs-notify-an-improvement-proposal/12734/11 "2013-04-30T12:36:11Z")
Actually this is already done and works fine in latest git for me. Did you test it on recent code?