How to use nested if inside jinja2 filter

Question

I am a writing a template file for virtual host and DNS inside the file should change as per environment host-name.Below is problem i am trying to solve:

server {
    listen 80;
    charset utf-8;
    server_name "{{ 'a.com if ansible_hostname='p.com' 'b.com' if   ansible_hostname= 'd.com' 'z.com' if ansible hostname is 'k.com' else 'default.com' }}";
    rewrite ^(.*)  https://$server_name$1 permanent;
}

How can i achieve this thing in template ie:

{{ 'a.com' if ansible_hostname='p.com' 'b.com' if ansible_hostname= 'd.com' 'z.com' if ansible hostname is 'k.com' else 'default.com' }}" `

I am new to jinja 2 and have no idea how to do this. Single if else statement is working but how can i use multiple if else statement for defining the value of a variable in the file.

Answer 1

So after some research work i was able to crack down the issue.We can

{% if ansible_hostname == 'a.com' %}
 {% set server = 'b.com' %}
{% elif ansible_hostname == 'c.com' %}
 {% set server = 'd.com' %}
{% else %}
 {% set server = 'define yourself' %}
{% endif %}

server {
    listen 80;
    charset utf-8;
    server_name {{ server }};
    rewrite ^(.*)  https://$server_name$1 permanent;
}

Still if someone can show the use of jinja2 filters for achieving this then that will be much appreciated.

Answer 2

I think no Jinja filter will be of use here but you can simply do it with a dict:

server {
    listen 80;
    charset utf-8;
    server_name {{ {"a.com": "b.com", "c.com": "d.com"}[ansible_hostname] | default("default.com") }};
    rewrite ^(.*)  https://$server_name$1 permanent;
}

That might work with 2 or a few more hosts but gets quickly dirty with increasing numbers. In general I think it would be more clean if such decisions would not happen in a template file. This could as well be a config option in either host_vars or group_vars. To stay with your example hosts you could have a file host_vars/a.com with the content

---

server: b.com

...

and a file host_vars/c.com with the content

---

server: d.com

...

In a file group_vars/all you can define the default value.

---

server: default.com

...