How to get the sum of two defined variables in Jinja2 ansible - ansible

Question

I have 04 server packs. Those are downloaded and extracted in a loop. I want to change the port numbers as 4000,4001,4002,4003 and 40004.
I have defined the variables in roles/myrole/vars/main.yml as follow
port: 4000
node:4
item:4
In my roles/myrole/tasks/main.yml, I have defined the tasks
- name: Change axis2 configs
template:
src: ~/myproject/roles/myrole/templates/axis2.xml.j2
dest: ~/myproject/{{ item }}/sever/axis2/axis2.xml
with_sequence: start=0 end={{ node }}
In the axis2 template I have added the variable as;
<parameter name="localMemberPort">{{ port }}</parameter>
{% set port = port + 1 %}
But I when I run the playbook, still the ports are replaced with 4000. How to do this task or is there another way to do this?

Answer 1

The {% set ... %} command only sets variables within the context of the template. It has no effect on subsequent iterations of the task. Since you're iterating using with_sequence, you can just add your loop variable to port like this:
<parameter name="localMemberPort">{{ port|int + item|int }}</parameter>
For example, the following playbook:
- hosts: localhost
gather_facts: false
vars:
node: 4
port: 4000
tasks:
- debug:
msg: >-
<parameter name="localMemberPort">{{ port|int + item|int }}</parameter>
with_sequence: start=0 end={{ node }}
Produces as output:
TASK [debug] *************************************************************************
ok: [localhost] => (item=0) => {
"msg": "<parameter name=\"localMemberPort\">4000</parameter>"
}
ok: [localhost] => (item=1) => {
"msg": "<parameter name=\"localMemberPort\">4001</parameter>"
}
ok: [localhost] => (item=2) => {
"msg": "<parameter name=\"localMemberPort\">4002</parameter>"
}
ok: [localhost] => (item=3) => {
"msg": "<parameter name=\"localMemberPort\">4003</parameter>"
}
ok: [localhost] => (item=4) => {
"msg": "<parameter name=\"localMemberPort\">4004</parameter>"
}
Incidentally, I hope you're not actually setting item in roles/myrole/vars/main.yml: this is the default loop variable name, and attempting to set it in a vars file like this is just going to cause confusion.

Answer 2

Change your roles/myrole/vars/main.yml as follows
port: 4000
node: 4
You don't need to specify item, because item is the current sequence number
And if you would like you can write a direct count in your task
- name: Change axis2 configs
template:
src: ~/myproject/roles/myrole/templates/axis2.xml.j2
dest: ~/myproject/{{ item }}/sever/axis2/axis2.xml
with_sequence: count={{ node }}
Just change your axis2 template to
<parameter name="localMemberPort">{{ port|int + item|int }}</parameter>
You don't need to set a variable in your logic for this purpose.
Hope this helps.

Answer 3

If anyone is interested in looping through a list and using the index value of each list item this what I did:
- name: "Install supervisord template for {{ role }} and notify supervisor of the change"
template:
src: "supervisord.conf.j2"
dest: "{{ supervisor_conf_dir }}/{{ role }}_{{ item.1 }}.conf"
owner: "{{ deploy_user }}"
group: "{{ deploy_user }}"
with_indexed_items:
- "{{ the_endpoints }}"
notify:
- "add_{{ role }}"
- "update_{{ role }}"
tags:
- "additional_templates"
- "supervisor_configs"
debug of this gives output where index.0 is the index value and index.1 is the item from the list:
item=(1, u'm19')
and use it in a template such as:
[program:{{ role }}_{{ item.1 }}]
autorestart = true
autostart = true
command = {{ opskit_dir }}/{{ role }}_{{ item.1 }}/bin/prometheus --web.external-url='https://{{ inventory_hostname }}:4434/{{ deploy_env }}-{{ role }}_{{ item.1 }}' --config.file='{{ opskit_dir }}/{{ role }}_{{ item.1 }}/conf/{{ role }}_{{ item.1 }}.yml' --storage.tsdb.path='{{ deploy_dir }}/data/{{ role }}
_{{ item.1 }}/data' --storage.tsdb.retention='365d' --log.level='debug' --web.listen-address=':{{ prometheus_internal_port|int + item.0|int }}'
directory = {{ opskit_dir }}/{{ role }}_{{ item.1 }}
redirect_stderr = true
stdout_logfile = {{ opskit_dir }}/log/{{ role }}_{{ item.1 }}.log
stdout_logfile_backups = 5
stdout_logfile_maxbytes = 10MB
stopwaitsecs = 300