William Turrell William Turrell - 1 month ago 13
JSON Question

Ansible ad-hoc command filter JSON output by key or property

I'd like to filter the JSON output of ad-hoc ansible commands - e.g. grab the long list of "facts" for multiple hosts, and show only one that could be several levels deep, such as

ansible_lsb.description
, so I can quickly compare what versions of software they're running, check accurate times or timezones, whatever.

This works:

ansible myserver -m setup -a 'filter=ansible_lsb'
myserver | SUCCESS => {
"ansible_facts": {
"ansible_lsb": {
"codename": "wheezy",
"description": "Debian GNU/Linux 7.11 (wheezy)",
"id": "Debian",
"major_release": "7",
"release": "7.11"
}
},
"changed": false
}


However, as the setup module docs state, "the filter option filters only the first level subkey below ansible_facts", so this fails:

ansible myserver -m setup -a 'filter=ansible_lsb.description'
myserver | SUCCESS => {
"ansible_facts": {},
"changed": false
}


(though for reference, you can use dot notation in other places such as a task's when conditional)

Is there a way to filter the JSON keys before the output is displayed?

Answer

Standard setup module can apply filter only on "top-level" facts.

To achieve what you want, you can make an action plugin with setup name to apply custom filters.

Working example ./action_plugins/setup.py:

from ansible.plugins.action import ActionBase

class ActionModule(ActionBase):

    def run(self, tmp=None, task_vars=None):

        def lookup(obj, path):
            return reduce(dict.get, path.split('.'), obj)

        result = super(ActionModule, self).run(tmp, task_vars)

        myfilter = self._task.args.get('myfilter', None)

        module_args = self._task.args.copy()
        if myfilter:
            module_args.pop('myfilter')

        module_return = self._execute_module(module_name='setup', module_args=module_args, task_vars=task_vars, tmp=tmp)

        if not module_return.get('failed') and myfilter:
            return {"changed":False, myfilter:lookup(module_return['ansible_facts'], myfilter)}
        else:
            return module_return

It calls original setup module stripping myfilter parameter, then filters result with simple reduce implementation if task is not failed and myfilter is set. Lookup function is very simple, so it will not work with lists, only with objects.

Result:

$ ansible myserver -m setup -a "myfilter=ansible_lsb.description"
myserver | SUCCESS => {
    "ansible_lsb.description": "Ubuntu 12.04.4 LTS",
    "changed": false
}
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