Create variable as dict using jinja2 within playbook

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Anth Courtney

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Oct 20, 2014, 11:55:28 PM10/20/14
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Hello there,

Is it possible to create a variable which is a dict using jinja2 within a playbook?

For example, I have the following (contrived) playbook, within which I am trying to create a 'host_info' dict which I can then access from a task:

---

- hosts: 127.0.0.1
  connection: local
  sudo: no

  vars:
    app_servers: 5
    ipaddress_base: "192.168.0"
    rmi_portbase: 10000
    host_info: |
      {%- for number in range(1,app_servers + 1) -%}
        {% set host = 'app' + number|string %}
       - hostname: host
       - ipaddress: {{ ipaddress_base }}.{{ number }}
       - rmi_port: {{ rmi_portbase|int + ( number * 10) }}
      {%- endfor %}

  tasks:

  - debug: var=item
    with_items: host_info

  - debug: var=item.hostname
    with_dict: host_info


However I can't seem to generate a dict as intended.

$ ansible-playbook -i "localhost," test.yml 

PLAY [127.0.0.1] ************************************************************** 

GATHERING FACTS *************************************************************** 
ok: [127.0.0.1]

TASK: [debug var=item] ******************************************************** 
ok: [127.0.0.1] => (item= - hostname: host
 - ipaddress: 192.168.0.1
 - rmi_port: 10010 - hostname: host
 - ipaddress: 192.168.0.2
 - rmi_port: 10020 - hostname: host
 - ipaddress: 192.168.0.3
 - rmi_port: 10030 - hostname: host
 - ipaddress: 192.168.0.4
 - rmi_port: 10040 - hostname: host
 - ipaddress: 192.168.0.5
 - rmi_port: 10050) => {
    "item": " - hostname: host\n - ipaddress: 192.168.0.1\n - rmi_port: 10010 - hostname: host\n - ipaddress: 192.168.0.2\n - rmi_port: 10020 - hostname: host\n - ipaddress: 192.168.0.3\n - rmi_port: 10030 - hostname: host\n - ipaddress: 192.168.0.4\n - rmi_port: 10040 - hostname: host\n - ipaddress: 192.168.0.5\n - rmi_port: 10050"
}

TASK: [debug var=item.hostname] *********************************************** 
fatal: [127.0.0.1] => with_dict expects a dict

FATAL: all hosts have already failed -- aborting

PLAY RECAP ******************************************************************** 
           to retry, use: --limit @/tmp/test.retry

127.0.0.1                  : ok=2    changed=0    unreachable=1    failed=0   


Any thoughts / assistance would be appreciated.

cheers,
Anth

James Cammarata

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Oct 23, 2014, 12:29:42 PM10/23/14
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Hi Anth,

Unfortunately, this cannot be done the way you're trying it. You're creating YAML after the YAML structure is already parsed, so the variable is just storing it as a string.

Instead of doing this, I would recommend using the add_host module (http://docs.ansible.com/add_host_module.html), which can also accept any additional variables you may wish to associate with that host entry.

Thanks!

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Steve Jacobs

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Apr 9, 2015, 11:33:56 AM4/9/15
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I realize this is an old thread, but why does this not work? It works as expected for arrays...

For instance see this blog post:

That works just fine, but if you try to modify this to output an array of dictionaries, or similar, ansible doesn't interpret the result correctly. Why?

Steve Jacobs

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Apr 9, 2015, 11:34:12 AM4/9/15
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Why is it possible to do with an array though?
- hosts: all
  connection: local
  gather_facts: false
  tasks:
    - set_fact:
        myvar: |
          {% set comma = joiner(",") %}
          [ {% for item in ['honey', 'bunch'] -%}
              {{ comma() }}"monkey"
          {%- endfor %}]
    - debug: var=myvar

PLAY [all] ********************************************************************

TASK: [set_fact ] *************************************************************
ok: [127.0.0.1]

TASK: [debug var=myvar] *******************************************************
ok: [127.0.0.1] => {
    "var": {
        "myvar": [
            "monkey",
            "monkey"
        ]
    }
}

PLAY RECAP ********************************************************************
127.0.0.1                  : ok=2    changed=0    unreachable=0    failed=0


But:
- hosts: all
  connection: local
  gather_facts: false
  tasks:
    - set_fact:
        myvar: |
          {% set comma = joiner(",") %}
          [ {% for item in ['honey', 'bunch'] -%}
              {{ comma() }}{ monkey: banana }
          {%- endfor %}]
    - debug: var=myvar

Produces:
TASK: [debug var=myvar] *******************************************************
ok: [127.0.0.1] => {
    "var": {
        "myvar": "[ { monkey: banana },{ monkey: banana }]"
    }
}

And:
- hosts: all
  connection: local
  gather_facts: false
  tasks:
    - set_fact:
        myvar: |
          {{ "\n" }}
          {%- for item in ['honey', 'bunch'] -%}
              - { monkey: banana }
          {% endfor %}
    - debug: var=myvar

TASK: [debug var=myvar] *******************************************************
ok: [127.0.0.1] => {
    "var": {
        "myvar": "\n- { monkey: banana }\n- { monkey: banana }\n"
    }
}

Why does one way work and the other way fail?

On Thursday, October 23, 2014 at 12:29:42 PM UTC-4, James Cammarata wrote:

Anand Buddhdev

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Apr 9, 2015, 6:37:12 PM4/9/15
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On Thursday, 9 April 2015 17:33:56 UTC+2, Steve Jacobs wrote:

I realize this is an old thread, but why does this not work? It works as expected for arrays...

I would also like to know this. I have previously tried to template playbooks using Jinja2, without success. I would like to ask again: wouldn't it be super if Ansible's playbooks were *first* run through Jinja2, so that we could use all of Jinja's features to customise some parts of playbooks?

Anand

Brian Coca

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Apr 9, 2015, 7:13:47 PM4/9/15
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> wouldn't it be super if Ansible's playbooks were *first* run through Jinja2, so that
> we could use all of Jinja's features to customise some parts of playbooks?

No.

short answer: it defeats the simplicity goal
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Steve Jacobs

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Apr 9, 2015, 7:14:40 PM4/9/15
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Sure I understand why not to do this. My question is why does one way work (arrays) and the other way (dicts) not work. Simple question, I can’t find an answer to it.

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Brian Coca

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Apr 9, 2015, 7:16:45 PM4/9/15
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The answer is that neither returns what you think it does, both return
a string, the issue is that with some fields they expect a string or
array or array in string (which then they split with , to get a real
array). Fields that expect dicts do not do any magic nor expect
strings at any point.


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Nehal J Wani

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Feb 13, 2017, 9:07:12 AM2/13/17
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I know this is  2 year old thread, but I bumped into this today and was able to create a dictionary. Something like this:

/tmp $ cat example.yml
- hosts: 127.0.0.1

  vars:
    app_servers: 5
    ipaddress_base: "192.168.0"
    rmi_portbase: 10000
    host_info: |
      {% set res = [] -%}
      {%- for number in range(1,app_servers + 1) -%}
        {% set ignored = res.extend([{
          'hostname': 'app' + number|string,
          'ipaddress': ipaddress_base + '.' + number|string,
          'rmi_port': rmi_portbase|int + ( number * 10)
          }]) -%}
      {%- endfor %}
      {{ res }}

  tasks:

    - debug: var=host_info
/tmp $ ansible-playbook example.yml
 [WARNING]: provided hosts list is empty, only localhost is available


PLAY [127.0.0.1] ***************************************************************

TASK [setup] *******************************************************************
ok: [127.0.0.1]

TASK [debug] *******************************************************************
ok: [127.0.0.1] => {
    "host_info": [
        {
            "hostname": "app1", 
            "ipaddress": "192.168.0.1", 
            "rmi_port": 10010
        }, 
        {
            "hostname": "app2", 
            "ipaddress": "192.168.0.2", 
            "rmi_port": 10020
        }, 
        {
            "hostname": "app3", 
            "ipaddress": "192.168.0.3", 
            "rmi_port": 10030
        }, 
        {
            "hostname": "app4", 
            "ipaddress": "192.168.0.4", 
            "rmi_port": 10040
        }, 
        {
            "hostname": "app5", 
            "ipaddress": "192.168.0.5", 
            "rmi_port": 10050
        }
    ]
}

PLAY RECAP *********************************************************************
127.0.0.1                  : ok=2    changed=0    unreachable=0    failed=0 
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