3 files changed, 34 insertions, 13 deletions
diff --git a/prepare-template.py b/prepare-template.py
new file mode 100755
index 0000000..aa27d38
--- /dev/null
+++ b/prepare-template.py
@@ -0,0 +1,15 @@
+#!/usr/bin/python
+
+import sys
+from yamljsonlib import template_replace
+
+
+def main():
+    with open(sys.argv[1]) as f:
+        template = string.Template(f.read())
+        lava_template = template_replace(template)
+        print lava_template
+
+
+if __name__ == '__main__':
+    main()
diff --git a/yaml-to-json.py b/yaml-to-json.py
index 4da2eae..c087d81 100755
--- a/yaml-to-json.py
+++ b/yaml-to-json.py
@@ -2,29 +2,18 @@
 
 import itertools
 import json
-import os
 import string
 import sys
 import yaml
 
+from yamljsonlib import template_replace
 
 # Find all placeholders in the input and replace them with the values of
 # equivalently-named environment variables.
 def main():
     with open(sys.argv[1]) as f:
         template = string.Template(f.read())
-
-    placeholders = map(lambda match: match.group('named', 'braced'),
-                       string.Template.pattern.finditer(template.template))
-    placeholders = set(filter(None, itertools.chain(*placeholders)))
-
-    # Pretend that missing environment variables are set to empty strings.
-    # It would be better to throw an error on missing environment variables,
-    # but this doesn't play nicely with Jenkins. When Jenkins adds parameters to
-    # a triggered job via a properties file, any parameters explicitly set to
-    # the empty string will be unset in the environment of the downstream job.
-    substitutions = {x: os.environ.get(x) or '' for x in placeholders}
-    lava_template = template.safe_substitute(substitutions)
+    lava_template = template_replace(template)
 
     # FIXME: use ordered dictionaries - see http://pyyaml.org/ticket/29
     config = json.dumps(yaml.safe_load(lava_template), indent=2, separators=(',', ': '))
diff --git a/yamljsonlib/__init__.py b/yamljsonlib/__init__.py
new file mode 100644
index 0000000..4b12525
--- /dev/null
+++ b/yamljsonlib/__init__.py
@@ -0,0 +1,17 @@
+import os
+import string
+
+
+def template_replace(template):
+    placeholders = map(lambda match: match.group('named', 'braced'),
+                       string.Template.pattern.finditer(template.template))
+    placeholders = set(filter(None, itertools.chain(*placeholders)))
+
+    # Pretend that missing environment variables are set to empty strings.
+    # It would be better to throw an error on missing environment variables,
+    # but this doesn't play nicely with Jenkins. When Jenkins adds parameters to
+    # a triggered job via a properties file, any parameters explicitly set to
+    # the empty string will be unset in the environment of the downstream job.
+    substitutions = {x: os.environ.get(x) or '' for x in placeholders}
+    lava_template = template.safe_substitute(substitutions)
+    return lava_template