cobbler: Set hostname using DHCP every boot on testnodes

This is for use with FOG.  When we create an OS image, the image
inherits the testnode's hostname that was used to create the image.

This rc.local snippet will make sure the testnode's hostname is set to
whatever the IP's PTR record is on every boot.

`rclocal_nameserver` should be set in the inventory groupvars.

Signed-off-by: David Galloway <dgallowa@redhat.com>

diff --git a/roles/cobbler/templates/snippets/cephlab_rc_local b/roles/cobbler/templates/snippets/cephlab_rc_local
index 853e1dc5f3b2c5213a4774354a7f3c2369a88216..9bb5aab18b62e27cd77797ec5a78f55929562a83 100644 (file)
--- a/roles/cobbler/templates/snippets/cephlab_rc_local
+++ b/roles/cobbler/templates/snippets/cephlab_rc_local
@@ -9,13 +9,56 @@
 #set script = '/etc/rc.local'
 #end if
 
-cat > $script << EOF
+cat > $script <<\EOF
 #!/bin/bash
 # First, redirect stderr and stdout to a logfile
 exec 2> /tmp/rc.local.log
 exec 1>&2
 set -ex
 
+{% if rclocal_nameserver is defined %}
+#raw
+
+# Don't error out if the `ip` command returns rc 1
+set +e
+
+attempts=0
+myips=""
+until [ "$myips" != "" ] || [ $attempts -ge 10 ]; do
+  myips=$(ip -4 addr | grep -oP '(?<=inet\s)\d+(\.\d+){3}' | grep -v '127.0.0.1\|127.0.1.1')
+  attempts=$[$attempts+1]
+  sleep 1
+done
+
+set -e
+
+if [ -n "$myips" ]; then
+  for ip in $myips; do
+    if timeout 1s ping -I $ip -nq -c1 {{ rclocal_nameserver }} 2>&1 >/dev/null; then
+      newhostname=$(dig +short -x $ip @{{ rclocal_nameserver }} | sed 's/\.com.*/\.com/g')
+        if [ -n "$newhostname" ]; then
+          hostname $newhostname
+          newdomain=$(hostname -d)
+          shorthostname=$(hostname -s)
+          echo $newhostname > /etc/hostname
+          if grep -q $newdomain /etc/hosts; then
+            # Replace
+            sed -i "s/.*$newdomain.*/$ip $newhostname $shorthostname/g" /etc/hosts
+          else
+            # Or add to top of file
+            sed -i '1i'$ip' '$newhostname' '$shorthostname'\' /etc/hosts
+          fi
+        fi
+    # Quit after first IP that can ping our nameserver
+    # in the extremely unlikely event the testnode has two IPs
+    break
+    fi
+  done
+fi
+
+#end raw
+{% endif %}
+
 # Only run once.
 if [ -e $lockfile ]; then
     exit 0