Use the postgres client to check if database is up.

core/assets/run.sh

@@ -15,13 +15,11 @@ function wait_for_postgres () {
 	# moving forward.
 	# TODO: Use python's psycopg2 module to do this in python instead of
 	# installing postgres-client in the image.
-	# until psql $DATABASE_URL -c '\l'; do
-	# 	>&2 echo "Postgres is unavailable - sleeping"
-	# 	sleep 1
-	# done
-	# >&2 echo "Postgres is up - continuing"
-	sleep 5
-	# TODO: Just sleep and do not require postgres client for the image maybe.
+	until psql $DATABASE_URL -c '\l'; do
+		>&2 echo "Postgres is unavailable - sleeping"
+		sleep 1
+	done
+	>&2 echo "Postgres is up - continuing"
 }