diff --git a/Dockerfile b/Dockerfile
index 33a873c6..665cb8f2 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -17,12 +17,12 @@ WORKDIR $RAILS_ROOT
 # Set Rails environment.
 ENV RAILS_ENV production
 
+COPY Gemfile* ./
+RUN bundle install --without development test --deployment --clean
+
 # Adding project files.
 COPY . .
 
-# Install gems.
-RUN bundle install --without development test --deployment --clean
-
 # Precompile assets.
 RUN bundle exec rake assets:clean
 RUN bundle exec rake assets:precompile
diff --git a/docker-compose.yml b/docker-compose.yml
index 2ba18f2f..4293ce93 100644
--- a/docker-compose.yml
+++ b/docker-compose.yml
@@ -10,9 +10,9 @@ services:
     ports:
       - 5000:80
 # When using sqlite3 as the database
-    volumes:
-      - ./db/production:/usr/src/app/db/production
-      - ./log:/usr/src/app/log
+#    volumes:
+#      - ./db/production:/usr/src/app/db/production
+#      - ./log:/usr/src/app/log
 # When using external logging
 #    logging:
 #      driver: $LOG_DRIVER
@@ -22,18 +22,18 @@ services:
 
 
 # When using postgresql as the database
-#    links:
-#      - db
+    links:
+      - db
 #
-#  db:
-#    image: postgres:9.5
-#    restart: on-failure
-#    ports:
-#      - 5432:5432
-#    volumes:
-#      - database_data:/var/lib/postgresql/data
-#    environment:
-#      - PGHOST=postgres
-#      - PGDATABASE=postgres
-#      - PGUSER=postgres
-#      - PGPASSWORD=password
+  db:
+    image: postgres:9.5
+    restart: on-failure
+    ports:
+      - 5432:5432
+    volumes:
+      - ./db/production:/var/lib/postgresql/data
+    environment:
+      - PGHOST=postgres
+      - PGDATABASE=postgres
+      - PGUSER=postgres
+      - PGPASSWORD=password
diff --git a/sample.env b/sample.env
index b256013b..ff094c8b 100644
--- a/sample.env
+++ b/sample.env
@@ -178,10 +178,21 @@ ENABLE_GOOGLE_CALENDAR_BUTTON=
 # ENABLE_SSL=true
 
 # Database settings
-# Greenlight works out of the box with sqlite3, but if postgresql is required, especially for production
-# These variables should also be included.
+#
+# Greenlight may work out of the box with sqlite3, but for production it is recommended to use postgresql.
+# In such case, these variables must be included.
+#
 # DB_ADAPTER=postgresql
 # DB_HOST=postgres.example.com
 # DB_NAME=greenlight_production
 # DB_USERNAME=postgres
 # DB_PASSWORD=password
+#
+# Note that the example provided, works for deployments based on the docker-compose script wich is also included. 
+# But should you need to use an external Postgres server, the right values for HOST, USERNAME and PASSWORD should be applied.
+#
+DB_ADAPTER=postgresql
+DB_HOST=db
+DB_NAME=greenlight_production
+DB_USERNAME=postgres
+DB_PASSWORD=password
diff --git a/scripts/image_build.sh b/scripts/image_build.sh
index 3b15a761..adf1e987 100755
--- a/scripts/image_build.sh
+++ b/scripts/image_build.sh
@@ -56,7 +56,12 @@ if [ "$CD_REF_NAME" != "master" ] && [[ "$CD_REF_NAME" != *"release"* ]] && ( [
 fi
 
 # Include sqlite for production
-sed -i "/^group :production do/a\ \ gem 'sqlite3', '~> 1.3.6'" Gemfile
+sqliteCount="$(grep "gem 'sqlite3'" Gemfile | wc -l)"
+
+if [ $sqliteCount -lt 2 ]; then
+  sed -i "/^group :production do/a\ \ gem 'sqlite3', '~> 1.3.6'" Gemfile
+fi
+
 # Set the version tag when it is a release or the commit sha was included.
 if [[ "$CD_REF_NAME" == *"release"* ]]; then
   export CD_VERSION_CODE=${CD_REF_NAME:8}