Properly support multi-document yaml files.

examples/todocontroller/deployment.yaml

@@ -2,6 +2,10 @@ apiVersion: apps/v1beta1
 kind: Deployment
 metadata:
   name: todo-controller-staging
+  annotations:
+    rules-k8s.bazel.io/foo: |
+      ---
+      foo: bar
 spec:
   replicas: 1
   template:

k8s/BUILD

@@ -72,4 +72,7 @@ par_binary(
     srcs = ["reverser.py"],
     main = "reverser.py",
     visibility = ["//visibility:public"],
+    deps = [
+        "@yaml",
+    ],
 )

k8s/resolver.py

@@ -50,7 +50,6 @@
         'publishing them.'))
 
 _THREADS = 32
-_DOCUMENT_DELIMITER = '---\n'
 
 
 def Resolve(input, string_to_digest):
@@ -79,7 +78,7 @@ def walk(o):
       return walk_string(o)
     return o
 
-  return yaml.dump(walk(yaml.load(input)))
+  return yaml.dump_all(map(walk, yaml.load_all(input)))
 
 
 def StringToDigest(string, overrides, transport):
@@ -186,10 +185,7 @@ def _StringToDigest(t):
       unseen_strings.remove(t)
     return StringToDigest(t, overrides, transport)
 
-  content = _DOCUMENT_DELIMITER.join([
-    Resolve(x, _StringToDigest)
-    for x in inputs.split(_DOCUMENT_DELIMITER)
-  ])
+  content = Resolve(inputs, _StringToDigest)
 
   if len(unseen_strings) > 0:
     print('The following image references were not found: [%s]' % "\n".join([

k8s/reverser.py

@@ -16,7 +16,7 @@
 from __future__ import print_function
 
 import argparse
-
+import yaml
 
 parser = argparse.ArgumentParser(
     description='Reverse a potential multi-document input.')
@@ -25,17 +25,14 @@
   '--template', action='store',
   help='The template file to resolve.')
 
-_DOCUMENT_DELIMITER = '---\n'
-
 
 def main():
   args = parser.parse_args()
 
   with open(args.template, 'r') as f:
     inputs = f.read()
 
-  content = _DOCUMENT_DELIMITER.join(
-    reversed(inputs.split(_DOCUMENT_DELIMITER)))
+  content = yaml.dump_all(reversed([x for x in yaml.load_all(inputs)]))
 
   print(content)