add openvpn exporter

Dockerfile

@@ -8,6 +8,8 @@ ENV GOPATH=/go
 WORKDIR $GOPATH
 RUN go get -u github.com/OperatorFoundation/shapeshifter-dispatcher/shapeshifter-dispatcher
 RUN strip $GOPATH/bin/shapeshifter-dispatcher
+RUN go get -u github.com/kumina/openvpn_exporter
+RUN strip $GOPATH/bin/openvpn_exporter
 
 FROM registry.git.autistici.org/ai3/docker/chaperone-base
 
@@ -16,6 +18,7 @@ FROM registry.git.autistici.org/ai3/docker/chaperone-base
 
 COPY --from=build /go/bin/shapeshifter-dispatcher /usr/local/bin/shapeshifter-dispatcher
 COPY --from=build /usr/sbin/openvpn /usr/sbin/openvpn
+COPY --from=build /got/bin/openvpn_exporter /usr/local/bin/openvpn_exporter
 COPY chaperone.d/ /etc/chaperone.d
 RUN apt-get -q update && env DEBIAN_FRONTEND=noninteractive apt-get install -y --no-install-recommends \
         openvpn libcap2-bin netcat-openbsd iptables\

chaperone.d/openvpn_exporter.conf

+openvpn-exporter.service: {
+     command: "/usr/local/bin/openvpn_exporter -openvpn.status_paths /tmp/openvpn-status-tcp,/tmp/openvpn-status-udp",
+     exit_kills: false
+}