fix backend

docker/apache/Dockerfile

@@ -14,6 +14,7 @@ RUN apt-get install -y \
     libmcrypt-dev \
     libreadline-dev \
     libfreetype6-dev \
+    libpq-dev \
     g++
 
 RUN docker-php-ext-install \
@@ -23,7 +24,9 @@ RUN docker-php-ext-install \
     opcache \
     calendar \
     pdo_mysql \
-    mysqli
+    mysqli \
+    pdo \
+    pdo_pgsql
 
 # 2. set up document root for apache
 COPY docker/apache/000-default.conf /etc/apache2/sites-available/000-default.conf