Merge pull request #2422 from justinmayer/print-settings

Add CLI argument to print current settings

docs/settings.rst

@@ -21,6 +21,12 @@ Settings are configured in the form of a Python module (a file). There is an
 <https://github.com/getpelican/pelican/raw/master/samples/pelican.conf.py>`_
 available for reference.
 
+To see a list of current settings in your environment, including both default
+and any customized values, run the following command (append one or more
+specific setting names as arguments to see values for those settings only)::
+
+    pelican --print-settings
+
 All the setting identifiers must be set in all-caps, otherwise they will not be
 processed. Setting values that are numbers (5, 20, etc.), booleans (True,
 False, None, etc.), dictionaries, or tuples should *not* be enclosed in
@@ -28,10 +34,9 @@ quotation marks. All other values (i.e., strings) *must* be enclosed in
 quotation marks.
 
 Unless otherwise specified, settings that refer to paths can be either absolute
-or relative to the configuration file.
-
-The settings you define in the configuration file will be passed to the
-templates, which allows you to use your settings to add site-wide content.
+or relative to the configuration file. The settings you define in the
+configuration file will be passed to the templates, which allows you to use your
+settings to add site-wide content.
 
 Here is a list of settings for Pelican:
 

pelican/__init__.py

@@ -7,6 +7,7 @@ import locale
 import logging
 import multiprocessing
 import os
+import pprint
 import re
 import sys
 import time
@@ -269,6 +270,32 @@ class Pelican(object):
             return writer(self.output_path, settings=self.settings)
 
 
+class PrintSettings(argparse.Action):
+    def __call__(self, parser, namespace, values, option_string):
+        instance, settings = get_instance(namespace)
+
+        if values:
+            # One or more arguments provided, so only print those settings
+            for setting in values:
+                if setting in settings:
+                    # Only add newline between setting name and value if dict
+                    if isinstance(settings[setting], dict):
+                        setting_format = '\n{}:\n{}'
+                    else:
+                        setting_format = '\n{}: {}'
+                    print(setting_format.format(
+                        setting,
+                        pprint.pformat(settings[setting])))
+                else:
+                    print('\n{} is not a recognized setting.'.format(setting))
+                    break
+        else:
+            # No argument was given to --print-settings, so print all settings
+            pprint.pprint(settings)
+
+        parser.exit()
+
+
 def parse_arguments():
     parser = argparse.ArgumentParser(
         description='A tool to generate a static blog, '
@@ -319,6 +346,12 @@ def parse_arguments():
                         help='Relaunch pelican each time a modification occurs'
                         ' on the content files.')
 
+    parser.add_argument('--print-settings', dest='print_settings', nargs='*',
+                        action=PrintSettings, metavar='SETTING_NAME',
+                        help='Print current configuration settings and exit. '
+                        'Append one or more setting name arguments to see the '
+                        'values for specific settings only.')
+
     parser.add_argument('--relative-urls', dest='relative_paths',
                         action='store_true',
                         help='Use relative urls in output, '
@@ -527,6 +560,7 @@ def main():
 
     try:
         pelican, settings = get_instance(args)
+
         readers = Readers(settings)
         reader_descs = sorted(set(['%s (%s)' %
                                    (type(r).__name__,