Don't run ceilometer-upgrade on unconfigured db

When the database backend is unconfigured, we currently
try to connection to nothing, and due to the retry logic around
the database connection, the user experience is "ceilometer-upgrade is
stuck".

This change keeps the database upgrade is the database is not
configured. And don't use the connection retry logic for upgrade.

Change-Id: I3fa2a332ecac6cb52c145f437f79b2aba43a4757

ceilometer/cmd/storage.py

@@ -42,8 +42,15 @@ def upgrade():
     if conf.skip_metering_database:
         LOG.info("Skipping metering database upgrade")
     else:
-        LOG.debug("Upgrading metering database")
-        storage.get_connection_from_config(conf).upgrade()
+
+        url = (getattr(conf.database, 'metering_connection') or
+               conf.database.connection)
+        if url:
+            LOG.debug("Upgrading metering database")
+            storage.get_connection(conf, url).upgrade()
+        else:
+            LOG.info("Skipping metering database upgrade, "
+                     "legacy database backend not configured.")
 
     if conf.skip_gnocchi_resource_types:
         LOG.info("Skipping Gnocchi resource types upgrade")

devstack/plugin.sh

@@ -232,6 +232,9 @@ function _ceilometer_configure_cache_backend {
 
 # Set configuration for storage backend.
 function _ceilometer_configure_storage_backend {
+
+    inidelete $CEILOMETER_CONF database metering_connection
+
     if [ "$CEILOMETER_BACKEND" = 'none' ] ; then
         # It's ok for the backend to be 'none', if panko is enabled. We do not
         # combine this condition with the outer if statement, so that the else