Use IP in hosts as variables in roles

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1

Hi Ansible guys,

I am using ansible to provision my django application composed of:

  • A Django Webserver on (Machine A IP : 1.1.1.1)
  • A PostgreSQL Database (Machine B IP: 2.2.2.2)
  • RabbitMQ Server (Machine C)
  • Celery Woekers (Machine D)

`
[database]
2.2.2.2

[django]
1.1.1.1
`

The main question I have is the following:
I’m using ansible to generate my settings.py for production. In this file, we need to define the database such as:

`

########## DATABASE CONFIGURATION

See: https://docs.djangoproject.com/en/dev/ref/settings/#databases

DATABASES = {
‘default’: {
‘ENGINE’: ‘django.db.backends.postgresql_psycopg2’,
‘NAME’: ‘toto’, # To be compliant with automatic exports from production
‘USER’: ‘postgres’,
‘PASSWORD’: ‘’,
‘HOST’: ‘2.2.2.2’, # MACHINE B IP ADRESS
‘PORT’: ‘5432’,
}
}
########## END DATABASE CONFIGURATION

`

Right now, I am hard coding the IP of my database in the settings.py file. But I don’t feel confortable with this approach. What if I need to deploy an other environment ? I was wondering how I could get dynamically the IP of my database server and use it as a variable in my differents templates.

If you have any ideas about how to proceed, I would be really happy to hear from you.

Regards.

2

Have a look at:

http://docs.ansible.com/ansible/faq.html#how-do-i-loop-over-a-list-of-hosts-in-a-group-inside-of-a-template
and
http://docs.ansible.com/ansible/faq.html#how-do-i-access-a-variable-of-the-first-host-in-a-group
I think this might get you pretty close to what you want.

Jon