Save and report nodepool image names

When building an image, save the hostname of the image to a file in
/etc.  Before running tox in jobs, cat that file.

This will help confirm which image was used to build a given node for
a particular job, and potentially help debug some issues we are
currently seeing.

Change-Id: I9d55b7223ea85c1137b460f049a0184d7e9ce53d

modules/openstack_project/files/nodepool/scripts/prepare_node.sh

@@ -40,6 +40,9 @@ then
     echo "127.0.1.1 $HOSTNAME" | sudo tee -a /etc/hosts
 fi
 
+echo $HOSTNAME > /tmp/image-hostname.txt
+sudo mv /tmp/image-hostname.txt /etc/image-hostname.txt
+
 # Fedora image doesn't come with wget
 if [ -f /usr/bin/yum ]; then
     sudo yum -y install wget

modules/openstack_project/files/slave_scripts/run-tox.sh

@@ -21,6 +21,8 @@ then
   exit 1
 fi
 
+cat /etc/image-hostname.txt
+
 /usr/local/jenkins/slave_scripts/jenkins-oom-grep.sh pre
 
 sudo /usr/local/jenkins/slave_scripts/jenkins-sudo-grep.sh pre

modules/openstack_project/files/slave_scripts/run-unittests.sh

@@ -20,6 +20,8 @@ export NOSE_HTML_OUT_FILE='nose_results.html'
 export TMPDIR=`/bin/mktemp -d`
 trap "rm -rf $TMPDIR" EXIT
 
+cat /etc/image-hostname.txt
+
 /usr/local/jenkins/slave_scripts/jenkins-oom-grep.sh pre
 
 sudo /usr/local/jenkins/slave_scripts/jenkins-sudo-grep.sh pre