Complex stdout check in Ansible - output

Question

I run a job on a remote server with Ansible. The stdout generates some output where sometimes errors show up. The error text is in the form of
#ERROR FMM0129E The following error was returned by the vSphere(TM) API: 'Cannot complete login due to an incorrect user name or password.'.
The thing is that some of these errors can safely be ignored and only these that are not in my false positive list should raise a fail.
My question is, can this be done in a pure Ansible way?
The only thing that comes to mind is the simple failed_when check which, in this case, falls short. I am thinking that these "complex" output checking should be done out of Ansible, invoking a python / shell / etc. script to help.

Answer 1

If you are remotely executing a shell command anyway then there's no reason why you couldn't wrap that in a shell script that returns a non 0 status code for the things you care about and then simply execute that via the script module.
example.sh
#!/bin/bash
randomInt=$[ 1 + $[ RANDOM % 10 ]]
echo $randomInt
if [ $randomInt == 1 ]; then
exit 1
else
exit 0
fi
And then use it like this in your playbook:
- name: run example.sh
script: example.sh
Ansible will automatically see any non 0 return codes as the task failing.

Answer 2

Instead of failed_when you could use ignore_errors: true which would get you into the position of passing the failing task and forwarding the stdout to another task. But I would not recommend this, since in my opinion a task should never ever report a failed state by intend. But if you feel this is an option for you, there even would be a way to reset the error counter so the Ansible stats at the end are correct.
- some: task
register: some_result
ignore_errors: true
- name: Reset errors after intentional fail
meta: clear_host_errors
when: some_result | failed
- another: task
check: "{{ some_result.stdout }}
when: some_result | failed
The last task then would check your stdout in a custom script or whatever you have and should report a failed state itself (return code != 0).
As far as I know the clear_host_errors feature is yet undocumented and the commit is about a month old, so I guess it will only be available in Ansible 2.0.1.
Another idea would be to wrap your task inside the script which checks the output or pipe it to that script. That obviously will only work if you run a shell command and not with any other ansible modules.
Other than those two options I don't think there is anything else available.