Added CentOS libvirt images

Change-Id: I536b5468e6b90a7368d74b05e02212788ee6e13c

libvirt/Dockerfile.centos_7

@@ -0,0 +1,19 @@
+ARG FROM=docker.io/centos:7
+FROM ${FROM}
+LABEL maintainer="mnaser@vexxhost.com"
+
+ARG CEPH_RELEASE=nautilus
+ARG PROJECT=nova
+ARG UID=42424
+ARG GID=42424
+
+RUN set -ex ;\
+    yum -y install centos-release-qemu-ev centos-release-ceph-${CEPH_RELEASE} ;\
+    yum -y install libcgroup-tools libvirt qemu-kvm-ev ;\
+    groupadd -g ${GID} ${PROJECT} ;\
+    useradd -u ${UID} -g ${PROJECT} -M -d /var/lib/${PROJECT} -s /usr/sbin/nologin -c "${PROJECT} user" ${PROJECT} ;\
+    mkdir -p /etc/${PROJECT} /var/log/${PROJECT} /var/lib/${PROJECT} /var/cache/${PROJECT} ;\
+    chown ${PROJECT}:${PROJECT} /etc/${PROJECT} /var/log/${PROJECT} /var/lib/${PROJECT} /var/cache/${PROJECT} ;\
+    usermod -a -G kvm ${PROJECT} ;\
+    yum clean all ;\
+    rm -rf /var/cache/yum

zuul.d/libvirt.yaml

@@ -40,6 +40,12 @@
         #    - latest-opensuse_15
         #    - "opensuse_15-{{ currentdate }}"
         #  dockerfile: Dockerfile.suse_15
+        - context: libvirt
+          repository: openstackhelm/libvirt
+          dockerfile: Dockerfile.centos_7
+          tags:
+            - latest-centos_7
+            - "centos_7-{{ currentdate }}"
         - context: libvirt
           repository: openstackhelm/libvirt
           dockerfile: Dockerfile.ubuntu_xenial