Ensure config regexes match the entire string

Oslo.config uses re.search() to check config values against the allowed
regex. This checks if the regex matches anywhere in the string, rather
than checking if the entire string matches the regex.

Make sure config options where the entire string should match the given
regex actually do so.

Change-Id: I9e30a24a4c0640f282f507d0a96640d3cdefe43c
Closes-Bug: #1815763

nova/conf/base.py

@@ -26,7 +26,7 @@ base_options = [
     cfg.StrOpt(
         'instance_usage_audit_period',
         default='month',
-        regex='(hour|month|day|year)(@([0-9]+))?',
+        regex='^(hour|month|day|year)(@([0-9]+))?$',
         help='''
 Time period to generate instance usages for. It is possible to define optional
 offset to given period by appending @ character followed by a number defining

nova/conf/cinder.py

@@ -24,7 +24,7 @@ cinder_group = cfg.OptGroup(
 cinder_opts = [
     cfg.StrOpt('catalog_info',
             default='volumev3::publicURL',
-            regex='(\w+):(\w*):(.*?)',
+            regex='^(\w+):(\w*):(.*?)$',
             help="""
 Info to match when looking for cinder in the service catalog.
 

nova/conf/serial_console.py

@@ -35,7 +35,7 @@ This service is typically executed on the controller node.
 """),
     cfg.StrOpt('port_range',
         default=DEFAULT_PORT_RANGE,
-        regex="\d+:\d+",
+        regex="^\d+:\d+$",
         help="""
 A range of TCP ports a guest can use for its backend.
 
@@ -45,7 +45,7 @@ instance won't get launched.
 
 Possible values:
 
-* Each string which passes the regex ``\d+:\d+`` For example ``10000:20000``.
+* Each string which passes the regex ``^\d+:\d+$`` For example ``10000:20000``.
   Be sure that the first port number is lower than the second port number
   and that both are in range from 0 to 65535.
 """),