ansible syntax to use "if-else" and "set"

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1

Hi All,

Im trying to choose ansible inventory host group conditionally.

  • name: Set group
    set_fact:
    group: |
    {% if c == 1 %}
    {% set group = ‘grp1’ %}
    {% elif c == 2 %}
    {% set group == ‘grp3’ %}
    {% else %}
    {% group == ‘grp4’ %}
    {% endif %}

  • debug:
    var=group

This doesnt seem to work.

Whats the right way to use if-else with ansible set??

Kinldy assist.

2

In your example of what you’re trying to do, you’re setting “group” inside of the template but never returning it to the task. What you might want is something like this:

  • name: Set Group
    set_fact:
    group: |
    {% if c == 1 %}
    grp1
    {% elif c ==2 %}
    grp3
    {% else %}
    grp4
    {% endif %}

– Steve

3

vars:
   group: ' {{ c ==1|ternary('gr1', c==2|ternary('grp3', 'grp4')) }}'

4

Hi Brian,

how can I use this if no of groups I have is like 10 ?

5

Just extent it with parentheses inside parentheses, not recommended since it makes it more or less unreadable so just use the solution Steve Rigler gave you.

6

Or maybe a series of set_fact: statements:

  • set_fact
    group: ‘BAD’

  • set_fact:
    group: grp1
    when: c == 1

  • set_fact:
    group: grp2
    when: c == 2

  • set_fact:
    group: grp3
    when: c == 3

[…etc…]

  • fail:

msg: “Invalid value for ‘c’ or ‘c’ not set!”

when: group == ‘BAD’

Regards, K.

7

Hi All,

Thankyou for the response, I used Rigler’s set_fact to determine the hostgroup like below

  • name: Set Group

set_fact:
group: |
{% if c == 1 %}

grp1
{% elif c ==2 %}
grp3
{% else %}
grp4
{% endif %}

  • name: Run the playbook
    hosts: “{{ hostvars.localhost.group }}”
    roles:
  • myplaybook.yml

My inventory file is like below:

hosts.ini

[appdagents]
grp1

grp2

grp3

.
.
.
grp8

[grp1:vars]
var1=“asfadfdsg”

[grp2:vars]
var1=“gsfgfh”
.
.
.

[grp1]
host1/db1 ansible_host=host1 db=db1
host1/db2 ansible_host=host1 db=db2

.
.
.
etc

Im getting below error.

 [WARNING]: **Could not match supplied host pattern, ignoring: grp1**



I did look into few github issues and it says any commented lines in hosts.ini could cause a problem and I dont have any commented lines. 

Kindly help
8

Hi All,

Thankyou for the response, I used Rigler's set_fact to determine the
hostgroup like below

- name: Set Group
  set_fact:
    group: |
      {% if c == 1 %}
      grp1
      {% elif c ==2 %}
      grp3
      {% else %}
      grp4
      {% endif %}

My hunch is that this produce a new line at the end.
You can check with
   - debug: var=group

So when using YAML multi line you need to control the newlines.

- will remove the last newline and {%- will remove any newline produced

by the YAML multiple lines

- name: Set Group
   set_fact:
     group: |-
       {% if c == 1 %}
       grp1
       {%- elif c ==2 %}
       grp3
       {%- else %}
       grp4
       {%- endif %}

Im getting below error.

[WARNING]: **Could not match supplied host pattern, ignoring: grp1**

It's probably a newline at the end.

9

HI Kai ,

I tried giving if in a single line and still get same error.

  • name : set fact variable
    set_fact:
    group: “{% if c == 1 %}grp1{% elif c == 2 %}grp2{% else %}grp3{% endif %}”

Same error as mentioned above

10

I noticed

Host “{{ hostvars.localhost.group}}”
Isn’t working.

What’s the best way to choose host groups on which my playbook should run dynamically kindly help.

11

Hi Rigler ,

Another doubt,

I’m trying to use this “if else block” with “set” inside a variable jinja2 file used in roles templating.

Cat varfile.yml.j2

12

You can't use set like this, that's why we have given you another way of doing this.