Set node eligibility to true when old client calls disable

api/nodes.go

@@ -68,7 +68,7 @@ type NodeDrainUpdateResponse struct {
 
 // UpdateDrain is used to update the drain strategy for a given node. If
 // markEligible is true and the drain is being removed, the node will be marked
-// as having its scheduling being elibile
+// as having its scheduling being eligible
 func (n *Nodes) UpdateDrain(nodeID string, spec *DrainSpec, markEligible bool, q *WriteOptions) (*NodeDrainUpdateResponse, error) {
 	req := &NodeUpdateDrainRequest{
 		NodeID:       nodeID,

command/agent/node_endpoint.go

@@ -124,6 +124,9 @@ func (s *HTTPServer) nodeToggleDrain(resp http.ResponseWriter, req *http.Request
 			drainRequest.DrainSpec = &api.DrainSpec{
 				Deadline: -1 * time.Second,
 			}
+		} else {
+			// If drain is disabled on an old client, mark the node as eligible for backwards compatibility
+			drainRequest.MarkEligible = true
 		}
 	} else {
 		if err := decodeBody(req, &drainRequest); err != nil {