[envoy] bump upstream per-connection buffer limit to 1 MiB

dilyevsky · dilyevsky · commit cf38c3dc43b5 · 2026-04-02T16:00:42.000-07:00
The 32 KiB default caused flow control pauses during high-throughput
transfers through the tunnel data path.
diff --git a/pkg/gateway/xds/translator/cluster.go b/pkg/gateway/xds/translator/cluster.go
@@ -33,7 +33,7 @@ import (
 const (
 	extensionOptionsKey = "envoy.extensions.upstreams.http.v3.HttpProtocolOptions"
 	// https://www.envoyproxy.io/docs/envoy/latest/api-v3/config/cluster/v3/cluster.proto#envoy-v3-api-field-config-cluster-v3-cluster-per-connection-buffer-limit-bytes
-	tcpClusterPerConnectionBufferLimitBytes = 32768
+	tcpClusterPerConnectionBufferLimitBytes = 1048576 // 1 MiB
 	tcpClusterPerConnectTimeout             = 10 * time.Second
 )
 

Original file line number	Diff line number	Diff line change
`@@ -33,7 +33,7 @@ import (`
`33`	`33`	`const (`
`34`	`34`	`extensionOptionsKey = "envoy.extensions.upstreams.http.v3.HttpProtocolOptions"`
`35`	`35`	`// https://www.envoyproxy.io/docs/envoy/latest/api-v3/config/cluster/v3/cluster.proto#envoy-v3-api-field-config-cluster-v3-cluster-per-connection-buffer-limit-bytes`
`36`		`- tcpClusterPerConnectionBufferLimitBytes = 32768`
	`36`	`+ tcpClusterPerConnectionBufferLimitBytes = 1048576 // 1 MiB`
`37`	`37`	`tcpClusterPerConnectTimeout = 10 * time.Second`
`38`	`38`	`)`
`39`	`39`