Replicated stateful application doesn't need its own directory.

docs/tutorials/stateful-application/Dockerfile

@@ -0,0 +1,17 @@
+# This is an image with Percona XtraBackup, mysql-client and ncat installed.
+FROM debian:jessie
+
+RUN \
+  echo "deb http://repo.percona.com/apt jessie main" > /etc/apt/sources.list.d/percona.list \
+  && echo "deb-src http://repo.percona.com/apt jessie main" >> /etc/apt/sources.list.d/percona.list \
+  && apt-key adv --keyserver keys.gnupg.net --recv-keys 8507EFA5
+
+RUN \
+  apt-get update && apt-get install -y --no-install-recommends \
+    percona-xtrabackup-24 \
+    mysql-client \
+    nmap \
+  && rm -rf /var/lib/apt/lists/*
+
+CMD ["bash"]
+