# Run handler on failed task **URL:** \ **Category:** Ansible Project\ **Created:** [April 15, 2014, 8:24am UTC](https://forum.ansible.com/t/run-handler-on-failed-task/15015 "2014-04-15T08:24:26Z")\ **Posts on this page:** 8\ **Page:** 1
**Author:** ![Joachim\_Friberg](https://avatars.discourse-cdn.com/v4/letter/j/6a8cbe/32.png) [@Joachim\_Friberg](https://forum.ansible.com/u/Joachim_Friberg)\ **Post date:** [April 15, 2014, 8:24am UTC](https://forum.ansible.com/t/run-handler-on-failed-task/15015/1 "2014-04-15T08:24:26Z")
Hi, So what I want to do, and have not yet found a way todo yet, is to run a handler if a taks fails rather then if it succeeds. For example I want to do a yum install mysql on a server, but this server does not have python-simplejson and/or other packages that is neccesary for Ansible. How do I then trigger a “fix” and then preferably rerun the failed task. Is this possible? Something similar to: - hosts: mysql user: admin vars: passwd: VeryHardPasswd user: analytics tasks: - name: create user Analytics mysql\_user: name={{ user }} password={{ passwd }} priv=_._:SELECT,‘SHOW DATABASES’ state=present login\_user=ROOT login\_password=PASSWORD register: mysql\_result ignore\_errors: True notify\_on\_fail: install mysqldb-python handlers: - name: Install mysqldb-python raw: sudo yum install -y MySQL-python ---
**Author:** ![Dick\_Davies](https://avatars.discourse-cdn.com/v4/letter/d/b9e5f3/32.png) [@Dick\_Davies](https://forum.ansible.com/u/Dick_Davies)\ **Post date:** [April 15, 2014, 3:34pm UTC](https://forum.ansible.com/t/run-handler-on-failed-task/15015/2 "2014-04-15T15:34:01Z")
In this specific case you'd just assert the python-simplejson package exists right? If it's already installed then nothing happens, and you'll be able to skip on to the other tasks. If of course you're in a catch-22 situation (can't run ansible to set up ansible pre-requisites), then you'll need to seed your base image with what's required. For example, my kickstarts bring up a machine with \* SSHd enabled and tcp/22 inbound permitted on the local firewall \* an 'ansible' account with a pre-defined list of SSH keys in its authorised\_keys file \* passwordless sudo configured for that account Everything else is managed by Ansible. This general approach also applies to CM with puppet, chef, etc. (which typically have much more requirements). ---
**Author:** ![Christian\_Rusa](https://avatars.discourse-cdn.com/v4/letter/c/f0a364/32.png) [@Christian\_Rusa](https://forum.ansible.com/u/Christian_Rusa)\ **Post date:** [April 16, 2014, 5:36am UTC](https://forum.ansible.com/t/run-handler-on-failed-task/15015/3 "2014-04-16T05:36:40Z")
To be honest, I would also be interested in a solution to this. Of course all the machines, that I install myself (preseed, kickstart, ...) meet the requirements for ansible. For already existing machines which should be managed by us, the requirements are somewhere in the middle of met or unmet. To my knowledge python-simplejson (required on Python 2.4 boxes) can only be installed using the raw module and not with the apt or yum module. Therefore this is a task which I'd not like to be executed on every run. Maybe the first task in the list could be an ansible ping and if it fails do some brute-force raw commands. .... And as writing this I answered my question 🙂 My prototype looks like this: - hosts: all    user: root    tasks:    - name: ping      ping:      register: result    - name: conditional task      raw: here\_your\_command      when: result|failed Cheers Christian ---
**Author:** ![Joachim\_Friberg](https://avatars.discourse-cdn.com/v4/letter/j/6a8cbe/32.png) [@Joachim\_Friberg](https://forum.ansible.com/u/Joachim_Friberg)\ **Post date:** [April 16, 2014, 8:41am UTC](https://forum.ansible.com/t/run-handler-on-failed-task/15015/4 "2014-04-16T08:41:56Z")
Hmm - I have fixed it with a when statement and then notify a handler that in turns install and notifies yet another handler. Thou this solution does not look nice and I would really like to not relay on any other managementsystem other then Ansible. My sollution to problem looks like this atm: - name: something register: something ignore\_errors: True - name: simplejson raw: “yum -y install python-simplejson” when: something|failed notify: - somethingAgain handlers: - name: somethingAgain … The above one works kinda but is not the best looking. Preffered would be similar to: - name: something register: something notify\_when: something|failed - simplejson handlers: - name: simplejson raw: “yum -y install python-simplejson” Does anyone know if something like this might be implemented in the near future or if anyone can point me to where I can suggest a “patch” 🙂 ---
**Author:** ![Michael\_DeHaan1](https://avatars.discourse-cdn.com/v4/letter/m/5e9695/32.png) [@Michael\_DeHaan1](https://forum.ansible.com/u/Michael_DeHaan1)\ **Post date:** [April 17, 2014, 2:23am UTC](https://forum.ansible.com/t/run-handler-on-failed-task/15015/5 "2014-04-17T02:23:39Z")
You are definitely overcomplicating it. There’s no reason to need the register really. - shell: yum -y install python-simplejson Yum naturally is smart enough to not do anything if the package is already installed, so it takes care of the “idempotence” (I kinda still hate the over-complexity of that word, but it’s a word) for you. ---
**Author:** ![Christian\_Rusa](https://avatars.discourse-cdn.com/v4/letter/c/f0a364/32.png) [@Christian\_Rusa](https://forum.ansible.com/u/Christian_Rusa)\ **Post date:** [April 17, 2014, 6:35am UTC](https://forum.ansible.com/t/run-handler-on-failed-task/15015/6 "2014-04-17T06:35:24Z")
As we have to manage a mixed environment, we do have different packagemanagers. So I often use when clauses like this when: ansible\_pkg\_mgr == "apt" I really like facts to be available in my playbooks. So my goal is/was to avoid running raw yum commands against a debian or apt against Red Hat in our global site playbook. A other thing I want to avoid is having a complicated documentation about which playbook to run against a server. I am dreaming of a one-size-fits-all playbook 🙂 Will the shell module work if the install of python-simplejson is required? At least for the install of python (Minimal debian does not have it) I need to go for raw. ---
**Author:** ![Brian\_Coca1](https://avatars.discourse-cdn.com/v4/letter/b/278dde/32.png) [@Brian\_Coca1](https://forum.ansible.com/u/Brian_Coca1)\ **Post date:** [April 17, 2014, 11:46am UTC](https://forum.ansible.com/t/run-handler-on-failed-task/15015/7 "2014-04-17T11:46:57Z")
- shell: yum install python-simplejson   ignore\_errors: true   changed\_when: False ugly but should work ---
**Author:** ![Michael\_DeHaan1](https://avatars.discourse-cdn.com/v4/letter/m/5e9695/32.png) [@Michael\_DeHaan1](https://forum.ansible.com/u/Michael_DeHaan1)\ **Post date:** [April 17, 2014, 11:57am UTC](https://forum.ansible.com/t/run-handler-on-failed-task/15015/8 "2014-04-17T11:57:52Z")
This is also a bit weird looking, but you could abuse the "removes" parameter to the shell command, which does not run a command when a binary does not exist. The downside is this makes your playbook look weirder. - shell: yum install python-simplejson removes=/usr/bin/yum referenced here: [http://docs.ansible.com/shell\_module.html](http://docs.ansible.com/shell_module.html) Generally this is done to prevent running installers a second time, and will not remove the indicated file. Another solution is usually to have the kickstart or base image slightly prepped in the case of those older OSes, but we definitely don't require it.