feat(xds): raise xDS gRPC server default receive limit and make it configurable by linmosko · Pull Request #9564 · envoyproxy/gateway

linmosko · 2026-07-22T21:04:11Z

Raises the xDS gRPC server's default receive limit from 4MiB to 32MiB,
and adds xdsServer.maxReceiveMessageSize to the EnvoyGateway API, allowing to raise the xDS gRPC server's receive limit.

At large resource counts, an Envoy proxy's delta xDS request on stream reconnect
echoes back the name and version of every resource it holds. This request can exceed
the 4MiB gRPC default, breaking the stream immediately with:

grpc: received message larger than max (4236915 vs. 4194304)

This leaves the proxy stuck on its last known-good configuration. Setting
maxReceiveMessageSize in the EnvoyGateway config resolves this.

Note: this limit applies only to what Envoy Gateway receives; the configuration
it sends to Envoy is not bounded by it.

PR Checklist

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chatgpt-codex-connector · 2026-07-22T21:08:31Z


+	if r.EnvoyGateway.XDSServer != nil && r.EnvoyGateway.XDSServer.MaxRecvMsgSize != nil {
+		maxRecvMsgSize, _ := r.EnvoyGateway.XDSServer.MaxRecvMsgSize.AsInt64()
+		baseKeepaliveOptions = append(baseKeepaliveOptions, grpc.MaxRecvMsgSize(int(maxRecvMsgSize)))


Configure the Envoy receive limit for large snapshots

For the documented scale case where the xDS snapshot/DiscoveryResponse is over 4MiB, Envoy Gateway is the sender and the Envoy proxy is the receiver; grpc.MaxRecvMsgSize here only raises the Go server's inbound DiscoveryRequest limit. Setting xdsServer.maxRecvMsgSize therefore leaves the advertised received message larger than max failure on Envoy's receive path unchanged, so large snapshots will still fail unless the Envoy bootstrap/client receive limit is configured instead.

Useful? React with 👍 / 👎.

DeltaDiscoveryRequest.resource_names_subscribe and DeltaDiscoveryRequest.initial_resource_versions from the XDS Client may grow large when the snapshot contains many resources. This is the concern addressed here. WDYT @codex ?

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linmosko · 2026-07-22T21:09:38Z

/retest

codecov · 2026-07-22T21:16:00Z

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 75.67%. Comparing base (bb7cdd1) to head (d5de40f).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #9564   +/-   ##
=======================================
  Coverage   75.67%   75.67%           
=======================================
  Files         254      254           
  Lines       41933    41942    +9     
=======================================
+ Hits        31731    31740    +9     
- Misses       8071     8072    +1     
+ Partials     2131     2130    -1

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linmosko · 2026-07-23T15:59:04Z

/retest

linmosko · 2026-07-23T17:11:18Z

/retest

guydc · 2026-07-23T22:29:33Z

+	// If unspecified, the default gRPC receive limit applies (4MiB).
+	//
+	// +optional
+	MaxRecvMsgSize *resource.Quantity `json:"maxRecvMsgSize,omitempty"`


nit: in extension manager we use MaxMessageSize, so maybe MaxReceiveMessageSize

Changed, thanks.

guydc

LGTM!

guydc · 2026-07-24T11:28:17Z

cc @zhaohuabing @arkodg - in case of very large snapshots, EG can reject XDS subscribe messages.

zhaohuabing · 2026-07-26T01:55:53Z

@linmosko could you please modify the the PR description? It's the xDS request from the Envoy to EG that caused the issue, not the snapshot.

zhaohuabing · 2026-07-26T01:59:55Z

@@ -0,0 +1 @@
+Added `xdsServer.maxReceiveMessageSize` field to the EnvoyGateway API, allowing operators to increase the xDS gRPC server's maximum receive message size when large xDS snapshots at scale exceed the default 4MiB limit, which previously caused "received message larger than max" stream errors.


Suggested change

Added `xdsServer.maxReceiveMessageSize` field to the EnvoyGateway API, allowing operators to increase the xDS gRPC server's maximum receive message size when large xDS snapshots at scale exceed the default 4MiB limit, which previously caused "received message larger than max" stream errors.

Added `xdsServer.maxReceiveMessageSize` to the EnvoyGateway API, allowing operators to raise the xDS gRPC server's receive limit. At large resource counts, an Envoy proxy's delta xDS request on stream reconnect can exceed the 4MiB gRPC default, which previously broke the stream with "received message larger than max" errors and left the proxy on its last known-good configuration.

Changed, thanks

Signed-off-by: Lin Moskovitch <lin.moskovitch@sap.com>

linmosko · 2026-07-26T06:31:17Z

/retest

Signed-off-by: Lin Moskovitch <lin.moskovitch@sap.com>

linmosko · 2026-07-27T12:17:38Z

/retest

linmosko · 2026-07-27T14:54:18Z

/retest

zhaohuabing

LGTM. Thanks!

linmosko · 2026-07-28T07:11:27Z

Hi @zhaohuabing !
Is there a known issue with the Hugo Docs action?

guydc · 2026-07-28T11:23:38Z

/retest

linmosko · 2026-07-28T12:14:17Z

/retest

guydc · 2026-07-28T12:59:19Z

/retest

…nfigurable (envoyproxy#9564) * feat(xds): add configurable max receive message size for xDS gRPC server Signed-off-by: Lin Moskovitch <lin.moskovitch@sap.com> * update release notes Signed-off-by: Lin Moskovitch <lin.moskovitch@sap.com> * test(xds): add coverage for MaxRecvMsgSize runner option Signed-off-by: Lin Moskovitch <lin.moskovitch@sap.com> * lint Signed-off-by: Lin Moskovitch <lin.moskovitch@sap.com> * refactor: rename MaxRecvMsgSize to MaxReceiveMessageSize for consistency Signed-off-by: Lin Moskovitch <lin.moskovitch@sap.com> * docs: improve MaxReceiveMessageSize comment and release note Signed-off-by: Lin Moskovitch <lin.moskovitch@sap.com> * feat(xds): set default max receive message size to 32MiB Signed-off-by: Lin Moskovitch <lin.moskovitch@sap.com> --------- Signed-off-by: Lin Moskovitch <lin.moskovitch@sap.com> Co-authored-by: Guy Daich <guy.daich@sap.com>

linmosko requested a review from a team as a code owner July 22, 2026 21:04

chatgpt-codex-connector Bot reviewed Jul 22, 2026

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linmosko requested a review from guydc July 23, 2026 14:40

guydc reviewed Jul 23, 2026

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linmosko force-pushed the feat/xds-grpc-max-recv-msg-size branch from 494fa76 to 054fa05 Compare July 24, 2026 08:27

linmosko requested a review from guydc July 24, 2026 08:28

guydc previously approved these changes Jul 24, 2026

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zhaohuabing reviewed Jul 26, 2026

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Comment thread api/v1alpha1/envoygateway_types.go Outdated

zhaohuabing reviewed Jul 26, 2026

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linmosko dismissed guydc’s stale review via 893f620 July 26, 2026 05:15

linmosko requested review from guydc and zhaohuabing July 26, 2026 05:21

linmosko added 6 commits July 26, 2026 08:38

feat(xds): add configurable max receive message size for xDS gRPC server

dd4e592

Signed-off-by: Lin Moskovitch <lin.moskovitch@sap.com>

update release notes

ae41a93

Signed-off-by: Lin Moskovitch <lin.moskovitch@sap.com>

test(xds): add coverage for MaxRecvMsgSize runner option

80f80c7

Signed-off-by: Lin Moskovitch <lin.moskovitch@sap.com>

lint

1a22b81

Signed-off-by: Lin Moskovitch <lin.moskovitch@sap.com>

refactor: rename MaxRecvMsgSize to MaxReceiveMessageSize for consistency

6fe1095

Signed-off-by: Lin Moskovitch <lin.moskovitch@sap.com>

docs: improve MaxReceiveMessageSize comment and release note

ef7fcbe

Signed-off-by: Lin Moskovitch <lin.moskovitch@sap.com>

linmosko force-pushed the feat/xds-grpc-max-recv-msg-size branch from 93f4915 to ef7fcbe Compare July 26, 2026 05:38

arkodg added this to the v1.9.0-rc.1 Release milestone Jul 26, 2026

arkodg reviewed Jul 26, 2026

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Comment thread api/v1alpha1/envoygateway_types.go Outdated

feat(xds): set default max receive message size to 32MiB

2d6fabf

Signed-off-by: Lin Moskovitch <lin.moskovitch@sap.com>

linmosko changed the title ~~feat(xds): add configurable max receive message size for xDS gRPC server~~ feat(xds): raise xDS gRPC server default receive limit and make it configurable Jul 27, 2026

Merge branch 'main' into feat/xds-grpc-max-recv-msg-size

bbdf1dd

linmosko requested a review from arkodg July 27, 2026 10:52

linmosko added 2 commits July 27, 2026 16:24

Merge branch 'main' into feat/xds-grpc-max-recv-msg-size

1ff3971

Merge branch 'main' into feat/xds-grpc-max-recv-msg-size

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arkodg approved these changes Jul 27, 2026

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guydc approved these changes Jul 27, 2026

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guydc and others added 2 commits July 27, 2026 12:56

Merge branch 'main' into feat/xds-grpc-max-recv-msg-size

ad8db43

Merge branch 'main' into feat/xds-grpc-max-recv-msg-size

40f549c

zhaohuabing approved these changes Jul 28, 2026

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Merge branch 'main' into feat/xds-grpc-max-recv-msg-size

d5de40f

guydc merged commit 8e32174 into envoyproxy:main Jul 28, 2026
114 of 124 checks passed

linmosko deleted the feat/xds-grpc-max-recv-msg-size branch July 28, 2026 15:54

		@@ -0,0 +1 @@
		Added `xdsServer.maxReceiveMessageSize` field to the EnvoyGateway API, allowing operators to increase the xDS gRPC server's maximum receive message size when large xDS snapshots at scale exceed the default 4MiB limit, which previously caused "received message larger than max" stream errors.

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