Templates & looping on json data structure

[Smain Kahlouch]

Hello,

I have a data structure gathered from a postgres db (external inventory) with a list of json data structures as follows :

[

{'name': conf1, 'myvar1': 1, 'myvar2': blabla},

{'name': conf2, 'myvar1': 44, 'myvar2': hello}

]

And i would like to use a kind of loop to create a file like :

[conf1]

param1 = 1

param2 = blabla

[conf2]

param1 = 44

param2 = hello

I've read in the ansible 

"

ansible allows Jinja2 loops and conditionals in templates, but in playbooks, we do not use them. Ansible templates are pure machine-parseable YAML. This is an rather important feature as it means it is possible to code-generate pieces of files, or to have other ecosystem tools read Ansible files. Not everyone will need this but it can unlock possibilities.

"

Is there a way to perform that kind of loops please ?

Regards,

Smana

[Smain Kahlouch]

my current script generates this output :

{

    "databases": {

        "hosts": [], 

        "vars": {}

    }, 

    "webservers": {

        "hosts": [

            "10.18.2.1", 

            "10.18.2.2", 

        ], 

        "vars": {}

    }, 

    "Site": {

        "children": [

            "databases", 

            "webservers"

        ], 

        "vars": [

            {

                "id": 4912, 

                "path": "test1.mp3", 

            }

            {

                "id": 4913, 

                "path": "test2.mp3", 

            }

        ]

    }

}

But i got this error when executing ansible :

/etc/ansible/services/mysite 0 # ansible all -i ./inventory.py

Traceback (most recent call last):

  File "/usr/bin/ansible", line 157, in <module>

    (runner, results) = cli.run(options, args)

  File "/usr/bin/ansible", line 79, in run

    inventory_manager = inventory.Inventory(options.inventory)

  File "/usr/lib/python2.7/dist-packages/ansible/inventory/__init__.py", line 101, in __init__

    self.parser = InventoryScript(filename=host_list)

  File "/usr/lib/python2.7/dist-packages/ansible/inventory/script.py", line 47, in __init__

    self.groups = self._parse(stderr)

  File "/usr/lib/python2.7/dist-packages/ansible/inventory/script.py", line 92, in _parse

    for k, v in data['vars'].iteritems():

AttributeError: 'list' object has no attribute 'iteritems'

I need to iterate on a list of several variables.

Do you think that's possible ?

Regards,

Smana

[Smain Kahlouch]

Any idea please ?

Regards,

Smana

[Kesten Broughton]

Smain,

Although full jinja2 templating is not available in tasks/playbooks, other features like pipes/filters are.

Try piping your datastructure with to_json like   

 - name: do a thing

   copy: src="{{item}}" dest=/foo

   with_items: {{output | to_json}}

I used something like this as well, where _requested_hosts was a dict passed in to a task like

 [main.yml]

 - include: { playbook.yml, _requested_hosts: {{some_dict_defined_in_vars_main.yml}} }

 

[playbook.yml]

 - debug: msg="{{_requested_hosts | to_json | capture(requested_hosts)}}"

The problem is that passing structures between playbook files seems to serialize it, and this deserializes it.

kesten

[Michael DeHaan]

I don't endorse the above suggestion by Kesten, and I'm pretty sure it's not going to work :)

You have a list data structure so iteritems isn't a method on a list.

If you just want to generate the config file I would do this as a template module:

(WARNING: untested general idea)

{% for entry in foo %}

    {% for (k,v) in entry.iteritems() %}

          {% if k == 'name' %}

[{{ v }}]

          {% endif %}

    {% endfor %}

   {% for (k,v) in entry.iteritems() %}

          {% if k != 'name' %}

{{ k }}={{ v }}

          {% endif %}

    {% endfor %}

{% endfor %}

- template: src=foo.j2 dest=wherever.out

Note that I'm answering your first question and not your second -- your variable structures are different in each.

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Michael DeHaan <mic...@ansibleworks.com>
CTO, AnsibleWorks, Inc.
http://www.ansibleworks.com/

[Smain Kahlouch]

Hello all,

For information i managed to do what i wanted.

i just changed my list into a dictionnary :

mylist = [ {'name': conf1, 'myvar1': 1, 'myvar2': blabla}, {'name': conf2, 'myvar1': 44, 'myvar2': hello} ]

mydict = { mylist }

then i used this dictionnary in my playbook as follows :

- name: foo configuration

  template: src=foo.cfg dest=/etc/foo/{{ item['name'] }}.sh

  with_items: $mydict

the "item" variable can also be use inside the template.

Thanks for your help.

Regards

[Michael DeHaan]

No need for the legacy variable here, BTW, just do this:

with_items: mydict

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