prevent updater from failing repeatedly on first startup while app volume is not ready

app/Dockerfile

@@ -9,6 +9,7 @@ RUN apk add --no-cache php7 php7-fpm \
 	git postgresql-client sudo
 
 ADD startup.sh /
+ADD updater.sh /
 ADD index.php /
 
 RUN sed -i.bak 's/^listen = 127.0.0.1:9000/listen = 9000/' /etc/php7/php-fpm.d/www.conf

app/updater.sh

@@ -0,0 +1,15 @@
+#!/bin/sh -ex
+
+while ! pg_isready -h $DB_HOST -U $DB_USER; do
+	echo waiting until $DB_HOST is ready...
+	sleep 3
+done
+
+DST_DIR=/var/www/html/tt-rss
+
+while [ ! -s $DST_DIR/config.php ]; do
+	echo waiting for $DST_DIR/config.php...
+	sleep 3
+done
+
+exec /usr/bin/php /var/www/html/tt-rss/update_daemon2.php

docker-compose.yml

@@ -43,12 +43,21 @@ services:
         - OWNER_UID=${OWNER_UID}
         - OWNER_GID=${OWNER_GID}
     restart: unless-stopped
+    environment:
+      - DB_TYPE=pgsql
+      - DB_HOST=db
+      - DB_NAME=${POSTGRES_USER}
+      - DB_USER=${POSTGRES_USER}
+      - DB_PASS=${POSTGRES_PASSWORD}
+      - OWNER_UID=${OWNER_UID}
+      - OWNER_GID=${OWNER_GID}
+      - SELF_URL_PATH=${SELF_URL_PATH}
     volumes:
       - app:/var/www/html
     depends_on:
       - app
     user: app
-    command: "php /var/www/html/tt-rss/update_daemon2.php"
+    command: /updater.sh
 
   web:
     build: ./web