Stupid Simple Jinja2 CLI

templater

#!/usr/bin/env python
import argparse
import jinja2
import json
import sys

"""
  read a template from stdin or a file, load variables from json or as an
  argument, and then output to file or stdout
"""
parser = argparse.ArgumentParser()

parser.add_argument('-c', '--config', default=None, help='load vars from file')
parser.add_argument('-v', '--vars', default=None, help='vars from input')
parser.add_argument('-i', '--input', default=None, help='source file')
parser.add_argument('-o', '--output', default=None, help='output file')
parser.add_argument('-a', '--append', default=False, action='store_true',
                    help='append to out')

(args, extra) = parser.parse_known_args()

source, data = None, None
if args.input:
    with open(args.input, 'r') as f:
        source = f.read()
else:
    source = sys.stdin.read()

if args.config:
    with open(args.config, 'r') as f:
        data = json.load(f)
elif args.vars:
    data = json.loads(args.vars)
else:
    data = {}

jenv = jinja2.Environment(trim_blocks=True)
result = jenv.from_string(source).render(**data)

if args.output:
    open_method = 'w'
    if args.append:
        open_method = 'a'

    with open(args.output, open_method) as f:
        f.write(result)
else:
    print result