yamplate

yamplate.py

from jinja2 import Environment, meta, StrictUndefined, exceptions
from yaml import load_all

def get_manifests(template_string, overrides):
    config = get_config(template_string)
    for k, v in overrides.items():
        config['parms'][k] = v
    rendered = render_jinja(template_string, config['parms'])
    results = list(load_all(rendered))
    try:
        'parms' in results[0]
        results.pop(0)
        return results
    except:
        print('error: template must contain config doc')
        exit(1)

def get_config(template_string):
    raw_template = Environment().parse(template_string)
    variables = meta.find_undeclared_variables(raw_template)
    tmp_values = {v: 'tempvalue' for v in variables}
    valid_template = render_jinja(template_string, tmp_values)
    results = list(load_all(valid_template))
    return results[0]

def render_jinja(string, parms):
    env = Environment(undefined=StrictUndefined)
    t = env.from_string(string)
    try:
        return t.render(parms)
    except exceptions.UndefinedError as e:
        print('template error:', e)
        exit(1)

call get_manifests with template string and config overrides

use with a string containing multiple '---' separated yaml docs. The first doc contains template default parameters and subsequent ones contain yaml fields with jinja2 {{parm}} parameters.

overrides is a dict object containing any desired parameters to override from the default ones set in the template

use with Kubernetes manifests to have a flatter deployment mechanism than helm