Avoid redundant rsync operations

In noncluster environments in a high-availability configuration, there
is only one target server to restore repository data onto. However, the
current implementation performs one rsync task per node in the
replication network. In a setup with one primary instance and two
passive replicas, this would amount to three rsync tasks with identical
or almost identical file lists.

Aside from the rsync task for transferring repository data from the
backup snapshot onto the target server, the other rsync operations per
replica are unnecessary.

Avoiding these redundant rsync tasks reduces the runtime of
ghe-restore-repositories by about 12 % for a customer with roughly 1 TB
of repository data.

With GHE_PARALLEL_ENABLED=yes configured, this change also prevents a
race condition, which could occur when multiple rsync processes try to
write to the same file on the target server at the same time.

Author: pluehne

share/github-backup-utils/ghe-restore-repositories

@@ -102,42 +102,49 @@ done > $tmp_list
 IFS=$OLDIFS
 bm_end "$(basename $0) - Building network list"
 
-# The server returns a list of routes:
-#
-# a/nw/a8/3f/02/100000855 dgit-node1 dgit-node2 dgit-node3
-# a/nw/a8/bc/8d/100000880 dgit-node1 dgit-node2 dgit-node4
-# a/nw/a5/06/81/100000659 dgit-node3 dgit-node2 dgit-node4
-# ...
-#
-# One route per line.
-#
-# NOTE: The route generation is performed on the appliance as it is considerably
-# more performant than performing over an SSH pipe.
-#
-bm_start "$(basename $0) - Transferring network list"
-cat $tmp_list | ghe-ssh "$GHE_HOSTNAME" -- sponge $remote_tmp_list
-cat $tmp_list | ghe_debug
-bm_end "$(basename $0) - Transferring network list"
-
-bm_start "$(basename $0) - Generating routes"
-restore_routes_script="github-env ./bin/dgit-cluster-restore-routes"
-if ghe-ssh "$GHE_HOSTNAME" test -e /usr/local/share/enterprise/ghe-restore-network-routes; then
-  restore_routes_script="/usr/local/share/enterprise/ghe-restore-network-routes"
+if $CLUSTER; then
+  # The server returns a list of routes:
+  #
+  # a/nw/a8/3f/02/100000855 dgit-node1 dgit-node2 dgit-node3
+  # a/nw/a8/bc/8d/100000880 dgit-node1 dgit-node2 dgit-node4
+  # a/nw/a5/06/81/100000659 dgit-node3 dgit-node2 dgit-node4
+  # ...
+  #
+  # One route per line.
+  #
+  # NOTE: The route generation is performed on the appliance as it is considerably
+  # more performant than performing over an SSH pipe.
+  #
+  bm_start "$(basename $0) - Transferring network list"
+  cat $tmp_list | ghe-ssh "$GHE_HOSTNAME" -- sponge $remote_tmp_list
+  cat $tmp_list | ghe_debug
+  bm_end "$(basename $0) - Transferring network list"
+
+  bm_start "$(basename $0) - Generating routes"
+  restore_routes_script="github-env ./bin/dgit-cluster-restore-routes"
+  if ghe-ssh "$GHE_HOSTNAME" test -e /usr/local/share/enterprise/ghe-restore-network-routes; then
+    restore_routes_script="/usr/local/share/enterprise/ghe-restore-network-routes"
+  fi
+  echo "cat $remote_tmp_list | $restore_routes_script | grep 'git-server-' > $remote_routes_list" | ghe-ssh "$GHE_HOSTNAME" -- /bin/bash
+  ghe-ssh "$GHE_HOSTNAME" -- cat $remote_routes_list | ghe_debug
+  bm_end "$(basename $0) - Generating routes"
+
+  bm_start "$(basename $0) - Fetching routes"
+  ghe-ssh "$GHE_HOSTNAME" -- gzip -c $remote_routes_list | gzip -d > $routes_list
+  cat $routes_list | ghe_debug
+  bm_end "$(basename $0) - Fetching routes"
+
+  bm_start "$(basename $0) - Processing routes"
+
+  cat $routes_list | awk -v tempdir="$tempdir" '{ for(i=2;i<=NF;i++){ print $1 > (tempdir"/"$i".rsync") }}'
+  cat $routes_list | awk '{ n = split($1, p, "/"); printf p[n] " /data/repositories/" $1; $1=""; print $0}' > $to_restore
+  ghe_debug "\n$(find "$tempdir" -maxdepth 1 -name '*.rsync')"
+  bm_end "$(basename $0) - Processing routes"
+else
+  # In noncluster setups, the primary instance owns all repository networks, so all network paths
+  # are to be synchronized to the primary instance.
+  cp "$tmp_list" "$tempdir/git-server-primary.rsync"
 fi
-echo "cat $remote_tmp_list | $restore_routes_script | grep 'git-server-' > $remote_routes_list" | ghe-ssh "$GHE_HOSTNAME" -- /bin/bash
-ghe-ssh "$GHE_HOSTNAME" -- cat $remote_routes_list | ghe_debug
-bm_end "$(basename $0) - Generating routes"
-
-bm_start "$(basename $0) - Fetching routes"
-ghe-ssh "$GHE_HOSTNAME" -- gzip -c $remote_routes_list | gzip -d > $routes_list
-cat $routes_list | ghe_debug
-bm_end "$(basename $0) - Fetching routes"
-
-bm_start "$(basename $0) - Processing routes"
-cat $routes_list | awk -v tempdir="$tempdir" '{ for(i=2;i<=NF;i++){ print $1 > (tempdir"/"$i".rsync") }}'
-cat $routes_list | awk '{ n = split($1, p, "/"); printf p[n] " /data/repositories/" $1; $1=""; print $0}' > $to_restore
-ghe_debug "\n$(find "$tempdir" -maxdepth 1 -name '*.rsync')"
-bm_end "$(basename $0) - Processing routes"
 
 if [ -z "$(find "$tempdir" -maxdepth 1 -name '*.rsync')" ]; then
   log_warn "Warning: no routes found, skipping repositories restore ..."