custom_plugins.py

from jinja2 import contextfilter

class FilterModule(object):
    ''' Extra filters '''

    def filters(self):
        return {
            'percent_of': self.percent_of,
            'of_ram': self.of_ram
        }

    @contextfilter
    def of_ram(self, ctx, percent):
        return self.percent_of(percent, ctx.resolve('ansible_memtotal_mb'))

    def percent_of(self, percent, total):
        return (total * (float(str(percent).strip('%')) / 100.0))