Permit arbitrary replacementsarbitrary

All placeholders in input are replaced with values of equivalently
named environment variables. If environment variable is unset,
replace with empty string. Note that this is a behaviour change:
previously, we would replace with the string 'None' if the
environment variable was unset.

Change-Id: I87e88d64a0146e305db9d4d4146d6b9607c2a5ef

1 files changed, 15 insertions, 27 deletions

diff --git a/yaml-to-json.py b/yaml-to-json.py
index 95a0c5c..3f60e2d 100755
--- a/yaml-to-json.py
+++ b/yaml-to-json.py
@@ -1,5 +1,6 @@
 #!/usr/bin/python
 
+import itertools
 import json
 import os
 import string
@@ -7,37 +8,24 @@ import sys
 import yaml
 
 
+#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())
 
-    lava_template = template.safe_substitute(
-        BOOT_URL=os.environ.get('BOOT_URL'),
-        BUILD_NUMBER=os.environ.get('BUILD_NUMBER'),
-        BUILD_URL=os.environ.get('BUILD_URL'),
-        BUNDLE_STREAM_NAME=os.environ.get('BUNDLE_STREAM_NAME'),
-        DATA_URL=os.environ.get('DATA_URL'),
-        DEVICE_TARGET=os.environ.get('DEVICE_TARGET'),
-        DEVICE_TYPE=os.environ.get('DEVICE_TYPE'),
-        DTB=os.environ.get('DTB'),
-        DTB_URL=os.environ.get('DTB_URL'),
-        GIT_BRANCH=os.environ.get('GIT_BRANCH'),
-        GIT_COMMIT=os.environ.get('GIT_COMMIT'),
-        GIT_URL=os.environ.get('GIT_URL'),
-        HWPACK_BUILD_URL=os.environ.get('HWPACK_BUILD_URL'),
-        IMAGE_URL=os.environ.get('IMAGE_URL'),
-        KERNEL=os.environ.get('KERNEL'),
-        KERNEL_URL=os.environ.get('KERNEL_URL'),
-        LAVA_SERVER=os.environ.get('LAVA_SERVER'),
-        ROOTFS_BUILD_NUMBER=os.environ.get('ROOTFS_BUILD_NUMBER'),
-        ROOTFS_BUILD_URL=os.environ.get('ROOTFS_BUILD_URL'),
-        STARTUP_NSH=os.environ.get('STARTUP_NSH'),
-        SYSTEM_URL=os.environ.get('SYSTEM_URL'),
-        defconfig=os.environ.get('defconfig'),
-        hwpack_type=os.environ.get('hwpack_type'),
-        kernel_config=os.environ.get('kernel_config'),
-        rootfs_type=os.environ.get('rootfs_type'),
-    )
+    placeholders = map(lambda match: match.group('named', 'braced'),
+            string.Template.pattern.finditer(template.template))
+    placeholders = filter(None, itertools.chain(*placeholders))
+
+    #Pretend that missing environment variables are set to empty string.
+    #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)
 
     # FIXME: use ordered dictionaries - see http://pyyaml.org/ticket/29
     config = json.dumps(yaml.safe_load(lava_template), indent=2, separators=(',', ': '))