Add ipxe file path variable and installation codes for CentOS

In _ironic-conductor-pxe-init.sh.tpl file,
there are only codes for ubuntu system.

However in Openstack-Helm especially in kolla image,
there are Ubuntu version and CentOS version.

So add codes for OS dependency check and ipxe file PATH for each OS.

Change-Id: I04886da64ae0dfda782bcd8d8d2cde960ab1db1d
Signed-off-by: TaewooLee <tw0410.lee@samsung.com>

ironic/templates/bin/_ironic-conductor-pxe-init.sh.tpl

@@ -18,10 +18,28 @@ limitations under the License.
 
 set -ex
 
-#NOTE(portdirect): this works round a limitation in Kolla images
+. /etc/os-release
-if ! dpkg -l ipxe; then
+HOST_OS=${HOST_OS:="${ID}"}
+FILEPATH=${FILEPATH:-/usr/lib/ipxe}
+
+if [ "x$ID" == "xubuntu" ]; then
+  #NOTE(portdirect): this works around a limitation in Kolla images
+  if ! dpkg -l ipxe; then
     apt-get update
     apt-get install ipxe -y
+  fi
+
+  FILEPATH=/usr/lib/ipxe
+
+elif [ "x$ID" == "xcentos" ]; then
+
+  if ! yum list installed ipxe-bootimgs >/dev/null 2>&1; then
+    yum update --nogpgcheck -y
+    yum install ipxe-bootimgs --nogpgcheck -y
+  fi
+
+  FILEPATH=/usr/share/ipxe
+
 fi
 
 mkdir -p /var/lib/openstack-helm/tftpboot