Issue 3943 - add support of configuration file

run.py

Index: run.py
diff --git a/run.py b/run.py
index 6661018b71c232bd2ba0e033bed09a83a7f051fa..f93b186d48c5156213d28546d946951d0fac49ba 100755
--- a/run.py
+++ b/run.py
@@ -84,39 +84,79 @@ class CrawlerApp:
         return ''
 
 
-def run():
-    parser = argparse.ArgumentParser(description='Run crawler')
-    parser.add_argument(
-        '-b', '--binary', type=str,
-        help='path to the Firefox binary'
-    )
-    parser.add_argument(
-        '-a', '--abpdir', type=str,
-        help='path to the Adblock Plus repository'
-    )
-    parser.add_argument(
-        '-f', '--filters', metavar='url', type=str, nargs='+',
-        default=["https://easylist-downloads.adblockplus.org/easylist.txt", "https://easylist-downloads.adblockplus.org/exceptionrules.txt"],
-        help='filter lists to install in Adblock Plus. The arguments can also have the format path=url, the data will be read from the specified path then.'
-    )
-    parser.add_argument(
-        '-t', '--timeout', type=int, default=300,
-        help='Load timeout (seconds)'
-    )
-    parser.add_argument(
-        '-x', '--maxtabs', type=int, default=15,
-        help='Maximal number of tabs to open in parallel'
-    )
-    parser.add_argument(
-        'list', type=str,
-        help='URL list to process'
-    )
-    parser.add_argument(
-        'outdir', type=str,
-        help='directory to write data into'
-    )
-    parameters = parser.parse_args()
+def read_as_json(file_path):
+    with open(file_path, mode='r') as json_file:
+        return json.load(json_file, encoding='UTF-8')
+
+
+class Parameters:
+    """This class loads config file and parses command line parameters.
+       Values are stored in attibutes of this class instance.
+    """
+    def __init__(self):
+        cli_parameters = vars(Parameters._parse_command_line())
+        config_parameters = Parameters._load_config(cli_parameters["config"])
+        for field in cli_parameters.keys():
+            value = cli_parameters[field]
+            if value is None:
+                value = config_parameters.get(field)
+            setattr(self, field, value)
+
+    @staticmethod
+    def _parse_command_line():
+        parser = argparse.ArgumentParser(description='Run crawler')
+        parser.add_argument(
+            '-c', '--config', type=str,
+            help='path to config file, example is config.json.example'
+        )
+        parser.add_argument(
+            '-b', '--binary', type=str,
+            help='path to the Firefox binary'
+        )
+        parser.add_argument(
+            '-a', '--abpdir', type=str,
+            help='path to the Adblock Plus repository'
+        )
+        parser.add_argument(
+            '-f', '--filters', metavar='url', type=str, nargs='+',
+            help='filter lists to install in Adblock Plus. The arguments can also have the format path=url, the data will be read from the specified path then.'
+        )
+        parser.add_argument(
+            '-t', '--timeout', type=int,
+            help='Load timeout (seconds)'
+        )
+        parser.add_argument(
+            '-x', '--maxtabs', type=int,
+            help='Maximal number of tabs to open in parallel'
+        )
+        parser.add_argument(
+            '-l', '--list', type=str,
+            help='URL list to process',
+        )
+        parser.add_argument(
+            '-o', '--outdir', type=str,
+            help='directory to write data into',
+        )
+        parameters = parser.parse_args()
+        return parameters
+
+    @staticmethod
+    def _load_config(config_file_path):
+        config = {
+          "filters": [
+            "https://easylist-downloads.adblockplus.org/easylist.txt",
+            "https://easylist-downloads.adblockplus.org/exceptionrules.txt"
+          ],
+          "timeout": 300,
+          "maxtabs": 15
+        }
+        if config_file_path is not None:
+            config.update(read_as_json(config_file_path))
+        return config
 
+
+def run():
+    parameters = Parameters()
     import buildtools.packagerGecko as packager
     cleanup = []
     try: