Sort JSON files to minimise git diffs

Sort and format JSON files to remove/minimise any diffs between
update-json runs. This also acts as a JSON validator to error when the
downloaded JSON file has been truncated.

Makefile

@@ -14,6 +14,7 @@ CODECOV := $(PYTHON) -m codecov
 
 MAKO_RENDER := etc/bin/mako-render
 API_VERSION_GEN := etc/bin/api_version_to_yaml.py
+SORT_JSON_FILE := etc/bin/sort_json_file.py
 TPL := $(PYTHON) $(MAKO_RENDER)
 MKDOCS := $(shell pwd)/$(VENV_DIR)/bin/mkdocs
 

etc/bin/sort_json_file.py

@@ -0,0 +1,29 @@
+#!/usr/bin/env python
+
+# Sort JSON file and print in fixed format
+# This lowers git diffs when a file has only changed by whitespace.
+
+
+import argparse
+import json
+import os
+
+
+def main(json_file_path, skip_missing_file):
+    if not os.path.isfile(json_file_path) and skip_missing_file:
+        return
+
+    with open(json_file_path, 'r') as fh:
+        loaded_json = json.load(fh)
+
+    with open(json_file_path, 'w') as fh:
+        json.dump(loaded_json, fh, indent=4, sort_keys=True)
+
+
+if __name__ == '__main__':
+    parser = argparse.ArgumentParser(description='Sort and format JSON file.')
+    parser.add_argument('json_file', metavar='FILE', type=str, help='JSON file to sort in place.')
+    parser.add_argument('--skip-missing-file', default=False, action='store_true', help='Do not fail on missing file.')
+
+    args = parser.parse_args()
+    main(args.json_file, args.skip_missing_file)

src/mako/deps.mako

@@ -194,9 +194,10 @@ help${agsuffix}:
 	url = info['discoveryRestUrl'].replace("$", "$$")
 	json_api_targets.append(fake_target)
 %>\
-${fake_target}:
+${fake_target}: $(PYTHON_BIN)
 	@mkdir -p ${target_dir}
 	@-curl --silent --show-error --fail --retry 3 -o '${target}' '${url}'
+	$(PYTHON) $(SORT_JSON_FILE) --skip-missing-file '${target}'
 % endfor
 
 update-json: ${' '.join(json_api_targets)}