Implement ForceDrainOverlimit config option.

config.go

@@ -62,8 +62,10 @@ type BehaviorConfig struct {
 	GlobalTimeout time.Duration
 	// The max number of global updates we can batch into a single peer request
 	GlobalBatchLimit int
-	// ForceGlobal forces global mode on all rate limit checks.
+	// ForceGlobal forces global behavior on all rate limit checks.
 	ForceGlobal bool
+	// ForceDrainOverlimit forces drain overlimit behavior on all rate limit checks.
+	ForceDrainOverlimit bool
 
 	// Number of concurrent requests that will be made to peers. Defaults to 100
 	GlobalPeerRequestsConcurrency int

gubernator.go

@@ -225,6 +225,9 @@ func (s *V1Instance) GetRateLimits(ctx context.Context, r *GetRateLimitsReq) (*G
 		if s.conf.Behaviors.ForceGlobal {
 			SetBehavior(&req.Behavior, Behavior_GLOBAL, true)
 		}
+		if s.conf.Behaviors.ForceDrainOverlimit {
+			SetBehavior(&req.Behavior, Behavior_DRAIN_OVERLIMIT, true)
+		}
 
 		peer, err = s.GetPeer(ctx, key)
 		if err != nil {