The buffer filter is used to stop filter iteration and wait for a fully buffered complete request. This is useful in different situations including protecting some applications from having to deal with partial requests and high network latency.
v2 API reference
This filter should be configured with the name envoy.buffer.
The buffer filter configuration can be overridden or disabled on a per-route basis by providing a BufferPerRoute configuration on the virtual host, route, or weighted cluster.