Add db preparation and webpack compilation when launching the container

docker-entrypoint.sh

@@ -0,0 +1,20 @@
+#!/bin/bash
+
+# Exit immediately if a command exits with a non-zero status.
+set -e
+
+# Create database, load schema, run migrations and seed data in an idempotent way.
+echo "Preparing database..."
+rake db:prepare
+echo "Database prepared."
+
+# Use webpack to build JS and CSS.
+echo "Compiling JS and CSS with webpack..."
+./bin/webpack
+echo "Webpack compilation completed."
+
+# Remove a potentially pre-existing server.pid for Rails.
+rm -f /app/tmp/pids/server.pid
+
+# Then exec the container's main process (what's set as CMD in the Dockerfile).
+exec "$@"