Fix CMD_DB_URL setting for postgres

abra.sh

@@ -1,2 +1,2 @@
-export ENTRYPOINT_CONF_VERSION=v10
+export ENTRYPOINT_CONF_VERSION=v11
 export PG_BACKUP_VERSION=v1

compose.postgresql.yml

@@ -2,7 +2,7 @@ version: "3.8"
 services:
   app:
     environment:
-      - CMD_DB_URL=
+      - POSTGRES_ENABLED=1
       - CMD_DB_NAME=codimd
       - CMD_DB_USER=codimd
       - CMD_DB_HOST=db

entrypoint.sh.tmpl

@@ -40,7 +40,9 @@ main() {
 
 main
 
-export CMD_DB_URL="${CMD_DB_URL:-postgres://$CMD_DB_USER:$CMD_DB_PASSWORD@$CMD_DB_HOST:5432/$CMD_DB_NAME}"
+if [ -n "$POSTGRES_ENABLED" ]; then
+export CMD_DB_URL="postgres://$CMD_DB_USER:$CMD_DB_PASSWORD@$CMD_DB_HOST:5432/$CMD_DB_NAME"
+fi
 
 # 3wc: `source /docker-entrypoint.sh -e` to load CMD_DB_URL for CLI scripts
 if [ ! "${1-}" == "-e" ]; then