Remove CentOS6 from nodepool scripts

With CentOS6 usage removed, remove special handling for it from nodepool
scripts.

Change-Id: Ife5ec9ade201dcd8f5969087dd2fc88be12dbebd

nodepool/elements/cache-bindep/install.d/50-cache-pkgs

@@ -50,27 +50,9 @@ echo "$PACKAGES" > $PACKAGESFILE
 PACKAGELIST=`/usr/bindep-env/bin/bindep -b -f $PACKAGESFILE || true`
 rm $PACKAGESFILE
 
-if grep "^CentOS release 6" /etc/redhat-release ; then
-    # --downloadonly is provided by the yum-plugin-downloadonly package on
-    # CentOS 6.x
-    CENTOS6=1
-    yum install -y yum-plugin-downloadonly
-else
-    CENTOS6=0
-fi
-
 if [ -f /usr/bin/apt-get ] ; then
     # --ignore-missing conflicts with set -e, so force it to be ok
     apt-get -y --ignore-missing -d install $PACKAGELIST || true
 else
-    if [ $CENTOS6 -eq 1 ] ; then
+    yum install -y --downloadonly $PACKAGELIST
-        # some packages may depend on python-setuptools, which is not
-        # installed and cannot be reinstalled on CentOS 6.x once yum
-        # has erased them, so use --skip-broken to avoid aborting; also
-        # on this platform --downloadonly causes yum to return nonzero
-        # even when it succeeds, so ignore its exit code
-        yum install -y --downloadonly --skip-broken $PACKAGELIST || true
-    else
-        yum install -y --downloadonly $PACKAGELIST
-    fi
 fi

nodepool/elements/cache-devstack/install.d/50-download-pkgs

@@ -27,31 +27,13 @@ if [[ ${YUM:-yum} == "dnf" ]]; then
     exit 0
 fi
 
-if grep "^CentOS release 6" /etc/redhat-release ; then
-    # --downloadonly is provided by the yum-plugin-downloadonly package on
-    # CentOS 6.x
-    CENTOS6=1
-    yum install -y yum-plugin-downloadonly
-else
-    CENTOS6=0
-fi
-
 while read line ; do
 
     if [ -f /usr/bin/apt-get ] ; then
         # --ignore-missing conflicts with set -e, so force it to be ok
         apt-get -y --ignore-missing -d install $line || true
     else
-        if [ $CENTOS6 -eq 1 ] ; then
+        yum install -y --downloadonly $line
-            # some packages may depend on python-setuptools, which is not
-            # installed and cannot be reinstalled on CentOS 6.x once yum
-            # has erased them, so use --skip-broken to avoid aborting; also
-            # on this platform --downloadonly causes yum to return nonzero
-            # even when it succeeds, so ignore its exit code
-            yum install -y --downloadonly --skip-broken $line || true
-        else
-            yum install -y --downloadonly $line
-        fi
     fi
 
 done < /tmp/pkgs-to-install

nodepool/scripts/prepare_node.sh

@@ -31,19 +31,7 @@ fi
 echo $HOSTNAME > /tmp/image-hostname.txt
 sudo mv /tmp/image-hostname.txt /etc/image-hostname.txt
 
-# HP Cloud centos6 images currently require an update to the
+if [ ! -f /etc/redhat-release ]; then
-# certificates file before they can connect to common services such as
-# fedora mirror for EPEL over https
-if [ -f /etc/redhat-release ]; then
-    if grep -q 'CentOS release 6' /etc/redhat-release; then
-        # chicken-and-egg ... hp cloud image has EPEL installed, but
-        # we can't connect to it...
-        # Note 'epel*' will match 0 or more repositories named epel,
-        # so it will work regardless of whether epel is actually
-        # installed.
-        sudo yum --disablerepo=epel* update -y ca-certificates
-    fi
-else
     # Cloud provider apt repos break us - so stop using them
     LSBDISTID=$(lsb_release -is)
     LSBDISTCODENAME=$(lsb_release -cs)