mariadb-clustercheck: Add a script handling signals

Since socat does not rewrite SIGTERM to exit 0 (see [1]) - let's fix it in a
different way.

[1]: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=809633

Change-Id: If27d93c509496651f8aa5e49a7d63b24eda91a8e

docker/mariadb/mariadb-clustercheck/Dockerfile.j2

@@ -6,8 +6,10 @@ LABEL maintainer="{{ maintainer }}" name="{{ image_name }}" build-date="{{ build
 {% block mariadb_clustercheck_header %}{% endblock %}
 
 COPY extend_start.sh /usr/local/bin/kolla_extend_start
+COPY socat_wrapper.sh /usr/local/bin/socat_wrapper
 
-RUN chmod 644 /usr/local/bin/kolla_extend_start
+RUN chmod 644 /usr/local/bin/kolla_extend_start && \
+    chmod 755 /usr/local/bin/socat_wrapper
 
 {% block mariadb_clustercheck_footer %}{% endblock %}
 {% block footer %}{% endblock %}

docker/mariadb/mariadb-clustercheck/socat_wrapper.sh

@@ -0,0 +1,19 @@
+#!/usr/bin/env bash
+
+catch_term() {
+    kill -TERM "$child" 2>/dev/null
+    exit 0
+}
+
+catch_quit() {
+    kill -QUIT "$child" 2>/dev/null
+    exit 0
+}
+
+trap catch_term SIGTERM
+trap catch_quit SIGQUIT
+
+socat "$@" &
+
+child=$!
+wait "$child"