rax-nova-agent: switch to $DISTRO_NAME

Check for the current distribution using $DISTRO_NAME instead of
`lsb_release`.
Also, remove the existency check, as $DISTRO_NAME is supposed to be
provided by distribution elements.

Change-Id: I2276c63e9ac43576da528a70235129800c093b3e

elements/rax-nova-agent/install.d/05-xen-tools

@@ -21,19 +21,16 @@ fi
 set -eu
 set -o pipefail
 
-DIST=$(lsb_release -is)
-[ -n "$DIST" ]
-
 XS_TOOLS_DIR=$(mktemp -d)
 mount -o loop /tmp/xs-tools.iso $XS_TOOLS_DIR
 pushd $XS_TOOLS_DIR/Linux
-case $DIST in
-    'Ubuntu'|'Debian')
+case "$DISTRO_NAME" in
+    'ubuntu'|'debian')
         # Seriously
         source versions.deb
         dpkg -i $XE_GUEST_UTILITIES_PKG_FILE_amd64
         ;;
-    'Fedora'|'CentOS' | 'openSUSE project')
+    'fedora'|'centos'|'centos7'|'opensuse')
         source versions.rpm
         rpm -Uvh $XE_GUEST_UTILITIES_PKG_FILE_x86_64
         ;;

elements/rax-nova-agent/install.d/10-nova-agent

@@ -32,10 +32,8 @@ runcmd:
     - ip addr show eth0 | grep inet || ( ifdown -a ; ifup -a )
 EOF
 
-DIST=$(lsb_release -is)
-[ -n "$DIST" ]
-case $DIST in
-    'Ubuntu'|'Debian')
+case "$DISTRO_NAME" in
+    'ubuntu'|'debian')
 
     # cloud-init / nova-agent sad panda hacks
     cat > /etc/init/nova-agent.conf <<'EOF'
@@ -87,7 +85,7 @@ respawn
 exec /sbin/getty -L 115200 hvc0 vt102
 EOF
     ;;
-    'Fedora'|'CentOS' | 'openSUSE project')
+    'fedora'|'centos'|'centos7'|'opensuse')
 
     cat > /usr/local/bin/run-nova-agent.sh <<'EOF'
 #!/bin/bash