lib/neutron: stop loading all config files into all processes

DHCP agent should not load core plugin config file; L3 agent has no
interest in metadata agent configuration file; etc. It's a mistake to
form a single global list of configuration files and pass it into all
processes. Every process should have its own list, that may or may not
have some files in common with other processes.

The only file that is common to all neutron processes is neutron.conf,
and we could in theory keep it into the common list. But I decided at
this point it's better to be explicit about what's loaded into services.
Also the order of arguments is important, and neutron.conf should always
be the first CLI argument, which is hard to achieve by keeping
neutron.conf file in the global list.

Plugins may be interested in loading additional files into neutron
processes. For example, dragonflow needs to load /etc/neutron/dragonflow.ini
into neutron-server. But we should not necessarily load all those files
into all processes, so such extendable lists should be per process.
Besides, neutron_server_config_add_new is already available to use to
append additional configuration files for neutron-server. That's why the
patch completely kills the NEUTRON_CONFIG_ARG variable.

Depends-On: I4bd54a41a45486a5601373f9a9cce74d7686d1aa
Change-Id: Ia3c3862399bba335db5edf9ea70f850fb2638d09

Author: Ihar Hrachyshka

lib/neutron

@@ -70,9 +70,6 @@ NEUTRON_ROOTWRAP=$(get_rootwrap_location neutron)
 NEUTRON_ROOTWRAP_CONF_FILE=$NEUTRON_CONF_DIR/rootwrap.conf
 NEUTRON_ROOTWRAP_DAEMON_CMD="sudo $NEUTRON_ROOTWRAP-daemon $NEUTRON_ROOTWRAP_CONF_FILE"
 
-# Add all enabled config files to a single config arg
-NEUTRON_CONFIG_ARG=${NEUTRON_CONFIG_ARG:-""}
-
 # Additional neutron api config files
 declare -a _NEUTRON_SERVER_EXTRA_CONF_FILES_ABS
 
@@ -347,7 +344,7 @@ function init_neutron_new {
     recreate_database neutron
 
     # Run Neutron db migrations
-    $NEUTRON_BIN_DIR/neutron-db-manage $NEUTRON_CONFIG_ARG upgrade heads
+    $NEUTRON_BIN_DIR/neutron-db-manage upgrade heads
 
     create_neutron_cache_dir
 }
@@ -426,20 +423,19 @@ function start_neutron_api {
 
 # start_neutron() - Start running processes, including screen
 function start_neutron_new {
-    _set_config_files
-
     # Start up the neutron agents if enabled
     # TODO(sc68cal) Make this pluggable so different DevStack plugins for different Neutron plugins
     # can resolve the $NEUTRON_AGENT_BINARY
     if is_service_enabled neutron-agent; then
-        run_process neutron-agent "$NEUTRON_BIN_DIR/$NEUTRON_AGENT_BINARY $NEUTRON_CONFIG_ARG"
+        # TODO(ihrachys) stop loading ml2_conf.ini into agents, instead load agent specific files
+        run_process neutron-agent "$NEUTRON_BIN_DIR/$NEUTRON_AGENT_BINARY --config-file $NEUTRON_CONF --config-file $NEUTRON_CORE_PLUGIN_CONF"
     fi
     if is_service_enabled neutron-dhcp; then
         neutron_plugin_configure_dhcp_agent $NEUTRON_DHCP_CONF
-        run_process neutron-dhcp "$NEUTRON_BIN_DIR/$NEUTRON_DHCP_BINARY $NEUTRON_CONFIG_ARG"
+        run_process neutron-dhcp "$NEUTRON_BIN_DIR/$NEUTRON_DHCP_BINARY --config-file $NEUTRON_CONF --config-file $NEUTRON_DHCP_CONF"
     fi
     if is_service_enabled neutron-l3; then
-        run_process neutron-l3 "$NEUTRON_BIN_DIR/$NEUTRON_L3_BINARY $NEUTRON_CONFIG_ARG"
+        run_process neutron-l3 "$NEUTRON_BIN_DIR/$NEUTRON_L3_BINARY --config-file $NEUTRON_CONF --config-file $NEUTRON_L3_CONF"
     fi
     if is_service_enabled neutron-api; then
         # XXX(sc68cal) - Here's where plugins can wire up their own networks instead
@@ -454,7 +450,7 @@ function start_neutron_new {
         fi
     fi
     if is_service_enabled neutron-metadata-agent; then
-        run_process neutron-metadata-agent "$NEUTRON_BIN_DIR/$NEUTRON_META_BINARY $NEUTRON_CONFIG_ARG"
+        run_process neutron-metadata-agent "$NEUTRON_BIN_DIR/$NEUTRON_META_BINARY --config-file $NEUTRON_CONF --config-file $NEUTRON_META_CONF"
     fi
 
     if is_service_enabled neutron-metering; then
@@ -480,30 +476,6 @@ function stop_neutron_new {
     fi
 }
 
-# Compile the lost of enabled config files
-function _set_config_files {
-
-    NEUTRON_CONFIG_ARG+=" --config-file $NEUTRON_CONF"
-
-    #TODO(sc68cal) OVS and LB agent uses settings in NEUTRON_CORE_PLUGIN_CONF (ml2_conf.ini) but others may not
-    if is_service_enabled neutron-agent; then
-        NEUTRON_CONFIG_ARG+=" --config-file $NEUTRON_CORE_PLUGIN_CONF"
-    fi
-
-    if is_service_enabled neutron-dhcp; then
-        NEUTRON_CONFIG_ARG+=" --config-file $NEUTRON_DHCP_CONF"
-    fi
-
-    if is_service_enabled neutron-l3; then
-        NEUTRON_CONFIG_ARG+=" --config-file $NEUTRON_L3_CONF"
-    fi
-
-    if is_service_enabled neutron-metadata-agent; then
-        NEUTRON_CONFIG_ARG+=" --config-file $NEUTRON_META_CONF"
-    fi
-
-}
-
 # neutron_service_plugin_class_add() - add service plugin class
 function neutron_service_plugin_class_add_new {
     local service_plugin_class=$1