Merge ~bjornt/maas:dns-crash-issues into maas:master

[Björn Tillenius]

LP: #1888536 - named.conf.options.inside.maas reverts to default

run-named always generated a blank config for bind when it's started.

It's questionable why we need to do that on every start, but for now, we
don't generate a config if a config is alrady there.

This should be safe enough to backport, and then we can revisit this
later, to see if we can fix it in a better way.

[Alberto Donato (ack)]

+1

review: Approve

diff --git a/snap/local/tree/bin/run-named b/snap/local/tree/bin/run-named
index bd0c252..13c167c 100755
--- a/snap/local/tree/bin/run-named
+++ b/snap/local/tree/bin/run-named
@@ -12,6 +12,7 @@ cp -f "$SNAP/usr/share/maas/bind/named.conf" "$SNAP_DATA/bind/"
 mkdir -p "$SNAP_DATA/bind/cache"
 
 # generate MAAS bind configuration
-MAAS_DNS_CONFIG_DIR="$SNAP_DATA/bind" "$SNAP/bin/maas-rack" setup-dns
+MAAS_DNS_CONFIG_DIR="$SNAP_DATA/bind" "$SNAP/bin/maas-rack" \
+    setup-dns --no-clobber
 
 exec "$SNAP/usr/sbin/named" -c "$SNAP_DATA/bind/named.conf" -g