Read --datasets option default value from DATASETS env var

convert.py

@@ -59,6 +59,7 @@ namespace_url_by_name = {"xml": "http://www.w3.org/XML/1998/namespace"}
 timings = None
 
 DAILY_PERIOD_RE = re.compile(r"(?P<year>\d{4})(?P<month>\d{2})(?P<day>\d{2})")
+DATASETS_ENV_VAR = 'DATASETS'
 FULL_ENV_VAR = 'FULL'
 
 
@@ -323,12 +324,19 @@ def toc_to_category_tree(xml_element, toc_dataset_json_stub_by_code):
 def main():
     global args
     global timings
+
+    datasets_from_env = os.getenv(DATASETS_ENV_VAR)
+    if datasets_from_env:
+        datasets_from_env = datasets_from_env.split(",")
+
     parser = argparse.ArgumentParser()
     parser.add_argument('source_dir', type=Path,
                         help='path of source directory containing Eurostat series in source format')
     parser.add_argument('target_dir', type=Path, help='path of target directory containing datasets & '
                         'series in DBnomics JSON and TSV formats')
-    parser.add_argument('--datasets', nargs='+', metavar='DATASET_CODE', help='convert only the given datasets (datasets codes, space separated)')
+    parser.add_argument('--datasets', nargs='+', metavar='DATASET_CODE',
+                        default=datasets_from_env,
+                        help='convert only the given datasets (datasets codes, space separated)')
     parser.add_argument('--full', action='store_true', default=os.getenv(FULL_ENV_VAR),
                         help='convert all datasets; default behavior is to convert what changed since last commit')
     parser.add_argument('--log', default='INFO', help='level of logging messages')