lib/apache: Use module paths instead of WSGI scripts

pbr's 'wsgi_scripts' entrypoint functionality is not long for this world
so we need to start working towards an alternative. We could start
packaging our own WSGI scripts in DevStack but using module paths seems
like a better option, particularly when it's supported by other WSGI
servers like gunicorn.

Currently only nova is migrated. We should switch additional projects as
they migrate and eventually remove the support for WSGI scripts
entirely.

Change-Id: I057dc635c01e54740ee04dfe7b39ef83db5dc180
Signed-off-by: Stephen Finucane <sfinucan@redhat.com>
Depends-on: https://review.opendev.org/c/openstack/nova/+/902687/

Author: stephenfin

lib/apache

@@ -237,13 +237,17 @@ function restart_apache_server {
     restart_service $APACHE_NAME
 }
 
+# write_uwsgi_config() - Create a new uWSGI config file
 function write_uwsgi_config {
     local conf=$1
     local wsgi=$2
     local url=$3
     local http=$4
-    local name=""
-    name=$(basename $wsgi)
+    local name=$5
+
+    if [ -z "$name" ]; then
+        name=$(basename $wsgi)
+    fi
 
     # create a home for the sockets; note don't use /tmp -- apache has
     # a private view of it on some platforms.
@@ -259,7 +263,15 @@ function write_uwsgi_config {
 
     # always cleanup given that we are using iniset here
     rm -rf $conf
-    iniset "$conf" uwsgi wsgi-file "$wsgi"
+    # Set either the module path or wsgi script path depending on what we've
+    # been given. Note that the regex isn't exhaustive - neither Python modules
+    # nor Python variables can start with a number - but it's "good enough"
+    if [[ "$wsgi" =~ ^[a-zA-Z0-9_.]+:[a-zA-Z0-9_]+$ ]]; then
+        iniset "$conf" uwsgi module "$wsgi"
+    else
+        deprecated 'Configuring uWSGI with a WSGI file is deprecated, use module paths instead'
+        iniset "$conf" uwsgi wsgi-file "$wsgi"
+    fi
     iniset "$conf" uwsgi processes $API_WORKERS
     # This is running standalone
     iniset "$conf" uwsgi master true
@@ -306,14 +318,25 @@ function write_local_uwsgi_http_config {
     local conf=$1
     local wsgi=$2
     local url=$3
-    name=$(basename $wsgi)
+    local name=$4
+
+    if [ -z "$name" ]; then
+        name=$(basename $wsgi)
+    fi
 
     # create a home for the sockets; note don't use /tmp -- apache has
     # a private view of it on some platforms.
 
     # always cleanup given that we are using iniset here
     rm -rf $conf
-    iniset "$conf" uwsgi wsgi-file "$wsgi"
+    # Set either the module path or wsgi script path depending on what we've
+    # been given
+    if [[ "$wsgi" =~ ^[a-zA-Z0-9_.]+:[a-zA-Z0-9_]+$ ]]; then
+        iniset "$conf" uwsgi module "$wsgi"
+    else
+        deprecated 'Configuring uWSGI with a WSGI file is deprecated, use module paths instead'
+        iniset "$conf" uwsgi wsgi-file "$wsgi"
+    fi
     port=$(get_random_port)
     iniset "$conf" uwsgi http-socket "$APACHE_LOCAL_HOST:$port"
     iniset "$conf" uwsgi processes $API_WORKERS

lib/nova

@@ -53,8 +53,8 @@ NOVA_COND_CONF=$NOVA_CONF_DIR/nova.conf
 NOVA_CPU_CONF=$NOVA_CONF_DIR/nova-cpu.conf
 NOVA_FAKE_CONF=$NOVA_CONF_DIR/nova-fake.conf
 NOVA_API_DB=${NOVA_API_DB:-nova_api}
-NOVA_UWSGI=$NOVA_BIN_DIR/nova-api-wsgi
-NOVA_METADATA_UWSGI=$NOVA_BIN_DIR/nova-metadata-wsgi
+NOVA_UWSGI=nova.wsgi.osapi_compute:application
+NOVA_METADATA_UWSGI=nova.wsgi.metadata:application
 NOVA_UWSGI_CONF=$NOVA_CONF_DIR/nova-api-uwsgi.ini
 NOVA_METADATA_UWSGI_CONF=$NOVA_CONF_DIR/nova-metadata-uwsgi.ini
 
@@ -549,11 +549,11 @@ function create_nova_conf {
     iniset $NOVA_CONF upgrade_levels compute "auto"
 
     if is_service_enabled n-api; then
-        write_uwsgi_config "$NOVA_UWSGI_CONF" "$NOVA_UWSGI" "/compute"
+        write_uwsgi_config "$NOVA_UWSGI_CONF" "$NOVA_UWSGI" "/compute" "" "nova-api"
     fi
 
     if is_service_enabled n-api-meta; then
-        write_uwsgi_config "$NOVA_METADATA_UWSGI_CONF" "$NOVA_METADATA_UWSGI" "" "$SERVICE_LISTEN_ADDRESS:${METADATA_SERVICE_PORT}"
+        write_uwsgi_config "$NOVA_METADATA_UWSGI_CONF" "$NOVA_METADATA_UWSGI" "" "$SERVICE_LISTEN_ADDRESS:${METADATA_SERVICE_PORT}" "nova-metadata"
     fi
 
     if is_service_enabled ceilometer; then