From dce0fedbef368857fc7be492f0adf9903f2de977 Mon Sep 17 00:00:00 2001
From: Ihar Hrachyshka <ihrachys@redhat.com>
Date: Mon, 1 Jul 2024 20:45:57 +0000
Subject: [PATCH] Gracefully handle empty db file on startup

In some situations, e.g. when ovsdb-tool is killed during db file
initialization, the file may end up empty. On next restart, the service
fails to start because the file format is invalid.

Ideally, ovs start scripts would handle this situation gracefully, as
tracked in https://issues.redhat.com/browse/FDP-689

But in the meantime, we can also handle the situation on operator's
side, by removing the empty file if present.

FYI a valid file always contains at least some data, because ovsdb-tool
adds a log entry with raft config as the first entry. See:

https://github.com/openvswitch/ovs/blob/56e315937eeb640d5d8f305988d133390445eaee/ovsdb/raft.c#L525

Resolves: https://issues.redhat.com/browse/OSPRH-8117
---
 templates/ovndbcluster/bin/cleanup.sh |  4 ++--
 templates/ovndbcluster/bin/functions  | 20 ++++++++++++++++++++
 templates/ovndbcluster/bin/setup.sh   |  9 ++++++++-
 3 files changed, 30 insertions(+), 3 deletions(-)
 create mode 100644 templates/ovndbcluster/bin/functions

diff --git a/templates/ovndbcluster/bin/cleanup.sh b/templates/ovndbcluster/bin/cleanup.sh
index bd3588eb..1004f5e5 100755
--- a/templates/ovndbcluster/bin/cleanup.sh
+++ b/templates/ovndbcluster/bin/cleanup.sh
@@ -14,9 +14,9 @@
 # License for the specific language governing permissions and limitations
 # under the License.
 set -ex
+source $(dirname $0)/functions
 
 DB_NAME="OVN_Northbound"
-DB_TYPE="{{ .DB_TYPE }}"
 if [[ "${DB_TYPE}" == "sb" ]]; then
     DB_NAME="OVN_Southbound"
 fi
@@ -42,5 +42,5 @@ fi
 # leaving the database file intact for -0 pod.
 if [[ "$(hostname)" != "{{ .SERVICE_NAME }}-0" ]]; then
     # now that we left, the database file is no longer valid
-    rm -f /etc/ovn/ovn${DB_TYPE}_db.db
+    cleanup_db_file
 fi
diff --git a/templates/ovndbcluster/bin/functions b/templates/ovndbcluster/bin/functions
new file mode 100644
index 00000000..eb901a26
--- /dev/null
+++ b/templates/ovndbcluster/bin/functions
@@ -0,0 +1,20 @@
+# Copyright 2024 Red Hat Inc.
+#
+# Licensed under the Apache License, Version 2.0 (the "License"); you may
+# not use this file except in compliance with the License. You may obtain
+# a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+# License for the specific language governing permissions and limitations
+# under the License.
+
+DB_TYPE="{{ .DB_TYPE }}"
+DB_FILE=/etc/ovn/ovn${DB_TYPE}_db.db
+
+function cleanup_db_file() {
+    rm -f $DB_FILE
+}
diff --git a/templates/ovndbcluster/bin/setup.sh b/templates/ovndbcluster/bin/setup.sh
index 89d0b61c..1d79b445 100755
--- a/templates/ovndbcluster/bin/setup.sh
+++ b/templates/ovndbcluster/bin/setup.sh
@@ -14,7 +14,8 @@
 # License for the specific language governing permissions and limitations
 # under the License.
 set -ex
-DB_TYPE="{{ .DB_TYPE }}"
+source $(dirname $0)/functions
+
 DB_PORT="{{ .DB_PORT }}"
 {{- if .TLS }}
 DB_SCHEME="pssl"
@@ -80,6 +81,12 @@ set "$@" --ovn-${DB_TYPE}-log=-vconsole:{{ .OVN_LOG_LEVEL }}
 # with a nearly empty log file
 set "$@" --ovn-${DB_TYPE}-logfile=/dev/null
 
+# If db file is empty, remove it; otherwise service won't start.
+# See https://issues.redhat.com/browse/FDP-689 for more details.
+if ! [ -s $DB_FILE ]; then
+    cleanup_db_file
+fi
+
 # don't log to file (we already log to console)
 $@ ${OPTS} run_${DB_TYPE}_ovsdb -- -vfile:off &