Add explode_yaml_file.py script

roles/gitian/files/explode_yaml_file.py

@@ -0,0 +1,92 @@
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+
+import argparse
+import os
+import ruamel.yaml
+
+from ruamel.yaml.scalarstring import DoubleQuotedScalarString
+
+# For a command like this...
+#
+# explode_yaml_file.py zcash/contrib/gitian-descriptors/gitian-linux.yml suites output_dir
+#
+# ...with a gitian-linux.yml file like this...
+#
+# ---
+# distro: "debian"
+# suites:
+# - "jessie"
+# - "stretch"
+# architectures:
+# - "amd64"
+#
+# ...will write out a structure like this:
+#
+# output_dir/
+# ├─ jessie/
+# │  └─ gitian-linux.yml  content:
+# │                       ---
+# │                       distro: "debian"
+# │                       suites:
+# │                       - "jessie"
+# │                       architectures:
+# │                       - "amd64"
+# │
+# └─ stretch
+#    └─ gitian-linux.yml  content:
+#                         ---
+#                         distro: "debian"
+#                         suites:
+#                         - "stretch"
+#                         architectures:
+#                         - "amd64"
+#
+# This approach is working around a limitation of gitian-builder: when
+# passed a descriptor file with more than one entry in 'suites', it
+# overwrites products of earlier builds with products of later builds.
+# We 'explode' our descriptor file into potentially many single-suite
+# descriptor files which we then pass to gitian-builder one at a time.
+
+
+parser = argparse.ArgumentParser(description='YAML file exploder')
+
+parser.add_argument('input_file_path',
+                    type=str,
+                    help='Path to the input file')
+
+parser.add_argument('key_to_explode',
+                    type=str,
+                    help='The key in the input file to explode (should be a sequence)')
+
+parser.add_argument('output_dir_path',
+                    type=str,
+                    help='Path to the output directory')
+
+args = parser.parse_args()
+
+yaml = ruamel.yaml.YAML()
+yaml.preserve_quotes = True
+
+input_file_path = args.input_file_path
+output_dir_path = args.output_dir_path
+
+file_name = os.path.basename(input_file_path)
+
+
+with open(input_file_path) as fp:
+    data = yaml.load(fp)
+
+sequence = data[args.key_to_explode]
+
+for item in sequence:
+    item_dir_path = os.path.join(output_dir_path, item)
+
+    if not os.path.exists(item_dir_path):
+        os.makedirs(item_dir_path)
+
+    data[args.key_to_explode] = [DoubleQuotedScalarString(item)]
+
+    output_file_path = os.path.join(item_dir_path, file_name)
+    with open(output_file_path, 'w') as fp:
+        yaml.dump(data, fp)