pass json to exec templates on stdin.

remove code for passing input params as environment variables.

cornfig/cornfig.py

@@ -3,10 +3,11 @@ import json
 import logging
 import os
 import pystache
-import subprocess
 import sys
+import tempfile
 from optparse import OptionParser
 from pystache.context import KeyNotFoundError
+from subprocess import Popen, PIPE
 
 logging.basicConfig(format='[%(asctime)s] [%(levelname)s] %(message)s', datefmt='%Y/%m/%d %I:%M:%S %p', level=logging.INFO)
 
@@ -49,10 +50,11 @@ def render_moustache(text, config):
   return r.render(text, config)
 
 def render_executable(path, config):
-  try:
-    return subprocess.check_output([path], env=flatten(config))
-  except subprocess.CalledProcessError as e:
-    raise CornfigException("config script failed: %s\n\nwith output:\n\n%s" % (path, e.output))
+  p = Popen([path], stdin=PIPE, stdout=PIPE, stderr=PIPE)
+  stdout, stderr = p.communicate(json.dumps(config))
+  p.wait()
+  if p.returncode != 0: raise CornfigException("config script failed: %s\n\nwith output:\n\n%s" % (path, stdout + stderr))
+  return stdout
 
 def read_config(path):
   try:
@@ -60,20 +62,6 @@ def read_config(path):
   except:
     raise CornfigException("invalid metadata file: %s" % path)
 
-# flatten a nested hash into a one-level hash
-# {x: {a: b} } => {x.a: b}
-def flatten(d, prefix='', res=None):
-  res = res or {}
-  for k, v in d.items():
-    key = (prefix + '.' + k) if len(prefix) > 0 else k
-    if isinstance(v, str) or isinstance(v, unicode):
-      res[key] = v
-    elif isinstance(v, dict):
-       res = dict(res.items() + flatten(v, key, res).items())
-    else:
-      raise CornfigException("expected only strings and hashes in config.")
-  return res
-
 # given a root directory, return a list of tuples
 # containing input and output paths
 def template_paths(root):

tests/cornfig_tests.py

@@ -49,9 +49,6 @@ def test_install_cornfig():
 def test_build_tree():
   assert_equals( build_tree(template_paths(TEMPLATES), CONFIG), OUTPUT )
 
-def test_flatten():
-  assert_equals( flatten({"x": {"a": "b", "c": "d"}, "y": "z"}), {"x.a": "b", "x.c": "d", "y": "z"} )
-
 def test_render_template():
   # execute executable files, moustache non-executables
   assert render_template(template("/etc/glance/script.conf"), {"x": "abc"}) == "abc\n"

tests/templates/etc/glance/script.conf

@@ -1,4 +1,7 @@
-#!/bin/sh
-set -u
-echo $x
-
+#!/usr/bin/env python
+import json
+import sys
+params = json.loads(sys.stdin.read())
+x = params["x"]
+if x is None: raise Exception("undefined: x")
+print x