Merge pull request #5906 from hashicorp/b-alloc-stale-updates

client: defensive against getting stale alloc updates

client/client.go

@@ -1767,6 +1767,9 @@ func (c *Client) allocSync() {
 // allocUpdates holds the results of receiving updated allocations from the
 // servers.
 type allocUpdates struct {
+	// index is index of server store snapshot used for fetching alloc status
+	index uint64
+
 	// pulled is the set of allocations that were downloaded from the servers.
 	pulled map[string]*structs.Allocation
 
@@ -1944,6 +1947,7 @@ OUTER:
 			filtered:      filtered,
 			pulled:        pulledAllocs,
 			migrateTokens: resp.MigrateTokens,
+			index:         resp.Index,
 		}
 
 		select {

client/util.go

@@ -33,7 +33,7 @@ func diffAllocs(existing map[string]uint64, allocs *allocUpdates) *diffResult {
 		_, filtered := allocs.filtered[existID]
 
 		// If not updated or filtered, removed
-		if !pulled && !filtered {
+		if !pulled && !filtered && allocs.index > existIndex {
 			result.removed = append(result.removed, existID)
 			continue
 		}