CI: use pre-existing ssh key on multinode jobs

In initially fixing the multinode key access to the
subnode, we inadvertently now broke ssh access
post-upgrade to the controller local host as it is
attempting to generate and leverage an ssh key locally
which can't really work. So instead, used the provided
keys if present.

Change-Id: I930f034c47bd1d2729ce43cd07c28cc7c1126402

Author: juliakreger

devstack/plugin.sh

@@ -77,14 +77,18 @@ function configure_generic_switch_ssh_keypair {
     fi
     # copy over stack user's authorized_keys to GENERIC_SWITCH_USER
     # mostly needed for multinode gate job
-    if [[ -e "$HOME/.ssh/authorized_keys" ]];then
+    if [[ -e "$HOME/.ssh/authorized_keys" ]]; then
         cat "$HOME/.ssh/authorized_keys" | sudo tee -a $GENERIC_SWITCH_KEY_AUTHORIZED_KEYS_FILE
     fi
     if [[ ! -e $GENERIC_SWITCH_KEY_FILE ]]; then
         if [[ ! -d $(dirname $GENERIC_SWITCH_KEY_FILE) ]]; then
             mkdir -p $(dirname $GENERIC_SWITCH_KEY_FILE)
         fi
-        echo -e 'n\n' | ssh-keygen -q -t rsa -P '' -m PEM -f $GENERIC_SWITCH_KEY_FILE
+        if [[ "$HOST_TOPLOGY" != "multinode" ]]; then
+            # NOTE(TheJulia): Self management of ssh keys only works locally
+            # and multinode CI jobs cannot leverage it.
+            echo -e 'n\n' | ssh-keygen -q -t rsa -P '' -m PEM -f $GENERIC_SWITCH_KEY_FILE
+        fi
     fi
     # NOTE(vsaienko) check for new line character, add if doesn't exist.
     if [[ "$(sudo tail -c1 $GENERIC_SWITCH_KEY_AUTHORIZED_KEYS_FILE | wc -l)" == "0" ]]; then
@@ -133,6 +137,13 @@ function configure_generic_switch {
         done
     fi
 
+    if [ -e "$HOME/.ssh/id_rsa" ] && [[ "$HOST_TOPOLOGY" == "multinode" ]]; then
+        # NOTE(TheJulia): Reset the key pair to utilize a pre-existing key,
+        # this is instead of generating one, which doesn't work in multinode
+        # environments. This is because the keys are managed and placed by zuul.
+        GENERIC_SWITCH_KEY_FILE="${HOME}/.ssh/id_rsa"
+    fi
+
     # Create generic_switch ml2 config
     for switch in $GENERIC_SWITCH_TEST_BRIDGE $IRONIC_VM_NETWORK_BRIDGE; do
         local bridge_mac
@@ -145,12 +156,6 @@ function configure_generic_switch {
     if [ -n "$HOST_TOPOLOGY_SUBNODES" ]; then
         # NOTE(vsaienko) with multinode topology we need to add switches from all
         # the subnodes to the config on primary node
-        # NOTE(TheJulia) We *also* need to use the local key which will have
-        # access to the subnode instead of attemping to configure our own,
-        # as the plugins execute separately.
-        if [ -e "$HOME/.ssh/id_rsa" ]; then
-            GENERIC_SWITCH_KEY_FILE="${HOME}/.ssh/id_rsa"
-        fi
         local cnt=0
         local section
         for node in $HOST_TOPOLOGY_SUBNODES; do