Make journald log collection persistent

We have had some job runs overrun the journald ring buffer which is used
by default resulting in losing older logs during the job runs. Update
the journald configuration to persistently store the journal so that we
can reliably retrieve those logs when jobs complete.

Change-Id: I5626ce76878287be220a8803f9dfe9a9da950d5b

nodepool/elements/nodepool-base/finalise.d/89-journald-persistent

@@ -0,0 +1,31 @@
+#!/bin/bash
+# Copyright (C) 2017 OpenStack Foundation
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#    http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
+# implied.
+#
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# dib-lint: disable=setu setpipefail
+if [ ${DIB_DEBUG_TRACE:-0} -gt 0 ]; then
+    set -x
+fi
+set -e
+
+# Journald default is to not persist logs to disk if /var/log/journal is
+# not present. Update the configuration to set storage to persistent which
+# will create /var/log/journal if necessary and store logs on disk. This
+# avoids the situation where test runs can fill the journald ring buffer
+# deleting older logs that may be important to the job.
+if [ -f /etc/systemd/journald.conf ] ; then
+    sed -i -e 's/#Storage=auto/Storage=persistent/' /etc/systemd/journald.conf
+fi