Make app container wait for DB

Dockerfile

@@ -20,6 +20,7 @@ RUN set -xe;\
 FROM reg.zknt.org/zknt/debian-php
 COPY --from=builder /var/www /var/www
 COPY entrypoint.sh /entrypoint.sh
+COPY wait-for-db.php /wait-for-db.php
 RUN apt-install php-curl php-zip php-bcmath php-intl php-mbstring php-xml optipng pngquant jpegoptim gifsicle ffmpeg php-imagick php-gd php-redis php-mysql &&\
   a2enmod rewrite &&\
   sed -i 's/AllowOverride None/AllowOverride All/g' /etc/apache2/apache2.conf

entrypoint.sh

@@ -3,6 +3,8 @@ set -xeo pipefail
 
 cp -r storage.skel/* storage/
 
+php /wait-for-db.php
+
 if [[ ! -e storage/.docker.init ]];
 then
 	echo "Fresh installation, initializing database..."

wait-for-db.php

@@ -0,0 +1,31 @@
+<?php
+
+$conn = mysqli_connect(
+    getenv('DB_HOST'),
+    getenv('DB_USERNAME'),
+    getenv('DB_PASSWORD'),
+    getenv('DB_DATABASE'),
+    getenv('DB_PORT')
+);
+
+$counter = 10;
+$count = 0;
+while (!$conn) {
+    echo("Waiting for Database... $count / $counter\n");
+    sleep(2);
+    $conn = mysqli_connect(
+        getenv('DB_HOST'),
+        getenv('DB_USERNAME'),
+        getenv('DB_PASSWORD'),
+        getenv('DB_DATABASE'),
+        getenv('DB_PORT')
+    );
+    $count++;
+    if($count == $counter) {
+        echo("Database did not respond after $counter tries, giving up\n");
+        die(1);
+    }
+}
+
+echo "Database is up\n";
+?>