Add ability to output the selector.

README.md

@@ -45,6 +45,7 @@ OpenDKIM package before using this tool.
 *   `-n` : use next month instead of this month when automatically generating a selector
 *   `-v` : log additional informational messages while processing
 *   `--no-dns` : do not attempt to automatically update DNS records
+*   `--selector` : output the selector and do nothing else
 
 If no `selector` is specified, one will be automatically generated based on the current
 month (or the next month if `-n` was used). Standard practice would be to omit the
@@ -56,6 +57,12 @@ records with the data in the generated `.txt` files, otherwise the script will t
 to automatically update the DNS records for all domains it's got DNS API support and
 information for.
 
+The `--selector` option can be used to cause the tool to output the generated selector
+on standard output for capture by a script. The `-n` option can be used in conjunction
+with `--selector`, other options will have no effect when `--selector` is specified.
+This is to assist with scripts to automatically upload the generated data files to a
+server for installation.
+
 The following options are also available for development and debugging. They should
 not be used under normal circumstances ("If you don't know what it's going to do, _DO
 NOT_ push the button." is a good rule to live by).

genkeys.py

@@ -206,6 +206,8 @@ def find_dnsapi_modules( pn ):
                      help = "Log debugging info and do not update DNS" )
 parser.add_argument( "--use-null", dest = 'use_null_dnsapi', action = 'store_true',
                      help = "Silently use the null DNS API instead of the real API" )
+parser.add_argument( "--selector", dest='output_selector', action = 'store_true',
+                     help = "Causes the generated selector to be output" )
 parser.add_argument( "selector", nargs = '?', default = None, help = "Selector to use" )
 args = parser.parse_args()
 
@@ -215,12 +217,37 @@ def find_dnsapi_modules( pn ):
     level = logging.WARN
 if args.log_debug:
     level = logging.DEBUG
-logging.basicConfig( level = level, format = "%(levelname)s: %(message)s" )
 
 should_update_dns = args.update_dns
 if never_update_dns:
     should_update_dns = False
 
+should_output_selector = args.output_selector
+if should_output_selector:
+    should_update_dns = False
+    level = logging.ERROR
+
+logging.basicConfig( level = level, format = "%(levelname)s: %(message)s" )
+
+# If we weren't given an explicit selector, the default is YYYYMM based on
+# either this month or next month.
+selector = args.selector
+if selector == None:
+    selector_date = datetime.date.today().replace( day = 1 )
+    if args.next_month:
+        y = selector_date.year
+        m = selector_date.month
+        m += 1
+        if m > 12:
+            m = 1
+            y += 1
+        selector_date = selector_date.replace( year = y, month = m )
+    selector = selector_date.strftime( "%Y%m" )
+logging.info( "Selector: %s", selector )
+if should_output_selector:
+    print selector
+    sys.exit( 0 )
+
 # Process dnsapi.ini
 # If we're supposed to update DNS records but don't have any definitions for
 # the DNS APIs, we record an error but we can continue to generate the keys
@@ -246,22 +273,6 @@ def find_dnsapi_modules( pn ):
     if item[1] not in key_names:
         key_names.append( item[1] )
 
-# If we weren't given an explicit selector, the default is YYYYMM based on
-# either this month or next month.
-selector = args.selector
-if selector == None:
-    selector_date = datetime.date.today().replace( day = 1 )
-    if args.next_month:
-        y = selector_date.year
-        m = selector_date.month
-        m += 1
-        if m > 12:
-            m = 1
-            y += 1
-        selector_date = selector_date.replace( year = y, month = m )
-    selector = selector_date.strftime( "%Y%m" )
-logging.info( "Selector: %s", selector )
-
 # Generate our keys, one per key name
 keys = {} # Key = key name (field 1) from domain_data[n], Value = key data dict
 for target in key_names: