How to get IP address of hostname inside jinja template

Question

Our saltstack is based on hostnames (webN., dbN., etc.). But for various things I need IPs of those servers. For now I had them stored in pillars, but the number of places I need to sync grows.

I tried to use publish + network.ip_addrs, but that kinda sucks, because it needs to do the whole salt-roundtrip just to resolve a hostname. Also it's dependent on the minions responding. Therefore I'm looking for a way to resolve hostname to IP in templates.

I assume that I could write a module for it somehow, but my python skills are very limited.

Answer 1

Reading through the ansible documentation, I found a much simpler solution. Here are my results.

enter the following into the template:

lookup hostname: {{ lookup('dig', 'google.ca.') }}

My jinja2 template:

# mytemplate.j2
## lookup directly
lookup hostname: {{ lookup('dig', 'google.ca.') }}

## in a variable
{% set fqdn = 'google.ca' %}
lookup hostname: {{ lookup('dig', fqdn) }}

Result:

# mytemplate.j2
## lookup directly
lookup hostname: 172.217.2.163

## in a variable
lookup hostname: 172.217.2.163

Answer 2

You could use a custom grain. Create file _grains/fqdn_ip.py in the state tree directory:

import socket

def fqdn_ip():
    return {
        'fqdn_ip': socket.gethostbyname(socket.getfqdn())
    }

In template:

{{ grains.fqdn_ip }}

Another way is use dnsutil module (requires dig command on minion):

{{ salt['dnsutil.A']('host.name.tld')[0] }}

Answer 3

I've see this: http://cnygaard.blogspot.com.es/2012/11/how-to-template-eth0-address-with.html

This is the easy way that I've found.

#init.sls:

...
...

/etc/swift/proxy-server.conf:              
   file:
     - managed                              
     - source: salt://swift/proxy-server.conf
     - template: jinja
     - context:
         proxy_ip: {{ salt['network.interfaces']()['eth0']['inet'][0]['address'] }}

And then:

#In proxy-server.conf

...

[filter:cache]
use = egg:swift#memcache
memcache_servers = {{ proxy_ip }}:11211

Answer 4

This is a very old post, but it is highly ranked in Google for getting the ipv4 address. As of salt 2015.5.8, the best way to get the primary ipv4 address is {{ grains['ipv4'][0] }}.