Add ContentUpdateRequest action to MPI by shaun-nx · Pull Request #1977 · nginx/agent

shaun-nx · 2026-10-22T16:43:36Z

Proposed changes

This PR is one part of issue nginx/nginx-gateway-fabric#5795 to enable NGINX Gateway Fabric to update TLS Certificates without requiring NGINX to reload.

Please see PR nginx/nginx-gateway-fabric#6163 to see how this change integrates.

This change adds a new CONTENT_UPDATE_REQUEST action to the Management Plane Interface. This enables the management plane to push file content updates to the data plane without requesting NGINX config validation or a reload cycle.

Issue nginx/nginx-gateway-fabric#5795

Checklist

Before creating a PR, run through this checklist and mark each as complete.

I have read the CONTRIBUTING document
I have run make install-tools and have attached any dependency changes to this pull request
If applicable, I have added tests that prove my fix is effective or that my feature works
If applicable, I have checked that any relevant tests pass after adding my changes
If applicable, I have updated any relevant documentation (README.md)
If applicable, I have tested my cross-platform changes on Ubuntu 22, Redhat 8, SUSE 15 and FreeBSD 13

codecov · 2026-10-22T16:49:05Z

Codecov Report

❌ Patch coverage is 20.41885% with 152 lines in your changes missing coverage. Please review.
✅ Project coverage is 88.00%. Comparing base (633c0c6) to head (d3604e8).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
internal/nginx/nginx_plugin.go	1.72%	114 Missing ⚠️
internal/command/command_plugin.go	23.07%	30 Missing ⚠️
internal/file/file_manager_service.go	76.47%	8 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1977      +/-   ##
==========================================
- Coverage   88.97%   88.00%   -0.97%     
==========================================
  Files         111      111              
  Lines       12457    12602     +145     
==========================================
+ Hits        11084    11091       +7     
- Misses       1371     1509     +138     
  Partials        2        2

Files with missing lines	Coverage Δ
internal/command/command_service.go	`87.46% <100.00%> (+0.07%)`	⬆️
internal/file/file_manager_service.go	`82.04% <76.47%> (-0.21%)`	⬇️
internal/command/command_plugin.go	`67.50% <23.07%> (-6.29%)`	⬇️
internal/nginx/nginx_plugin.go	`62.69% <1.72%> (-18.28%)`	⬇️

... and 1 file with indirect coverage changes

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Copilot

🟡 Changes recommended

Content updates bypass existing request ordering and target-instance validation, allowing stale certificate writes and file mutations for nonexistent targets.

2 open issues

3 files not reviewed

api/grpc/mpi/v1/command.pb.go: Generated file
api/grpc/mpi/v1/command.pb.validate.go: Generated file
internal/file/filefakes/fake_file_manager_service_interface.go: Generated file

What changed in this PR

Adds a file-only update operation to NGINX Agent’s Management Plane Interface, supporting Gateway Fabric’s TLS certificate rotation without NGINX validation or reload.

Changes:

Defines ContentUpdateRequest and regenerates protocol bindings, validation, and documentation.
Routes content updates through command and NGINX plugins, reusing file processing and rollback logic.
Extends test helpers, service fakes, and subscription assertions.

File	Description
test/protos/management_plane_request.go	Adds a content-update request helper.
internal/nginx/nginx_plugin.go	Handles content updates and rollback without reloading.
internal/nginx/nginx_plugin_test.go	Checks the new topic subscription.
internal/file/filefakes/fake_file_manager_service_interface.go	Adds content-update support to the service fake.
internal/file/file_manager_service.go	Shares file processing between apply and content updates.
internal/command/command_plugin.go	Dispatches content updates with feature and server checks.
internal/bus/topics.go	Defines the content-update topic.
docs/proto/protos.md	Documents the new protocol operation.
api/grpc/mpi/v1/command.proto	Defines the request and response enum value.
api/grpc/mpi/v1/command.pb.validate.go	Adds generated request validation.
api/grpc/mpi/v1/command.pb.go	Adds generated protocol bindings.

_{Review effort: Balanced}

shaun-nx · 2026-10-23T12:41:40Z

+func (cp *CommandPlugin) handleContentUpdateRequest(newCtx context.Context, message *mpi.ManagementPlaneRequest) {
+	cfg := cp.config()
+	if cfg.IsFeatureEnabled(pkgConfig.FeatureConfiguration) {
+		cp.messagePipe.Process(newCtx, &bus.Message{Topic: bus.ContentUpdateRequestTopic, Data: message})


AI generated response by Claude

The queue exists to serialize config applies per instance (which involve validation + reload). Content updates are designed to be a lighter-weight operation (no reload). Whether they truly need to be serialized with config applies depends on the use case. The Copilot scenario (apply A queued, content update C runs before apply B, then B overwrites C's files) is theoretically possible but only if both operations target the same files — which seems unlikely given that content updates are intended for TLS certs while config applies are for nginx config.

Open to opinions on this one. I do address with Claude's observation. Files affected by ContentUpdateRequest are logically separated on NGF's side, so they shouldn't go down the same code path.

salonichf5

great work with this just had a question

salonichf5 · 2026-10-22T18:37:14Z

+func (cp *CommandPlugin) handleContentUpdateRequest(newCtx context.Context, message *mpi.ManagementPlaneRequest) {
+	cfg := cp.config()
+	if cfg.IsFeatureEnabled(pkgConfig.FeatureConfiguration) {
+		cp.messagePipe.Process(newCtx, &bus.Message{Topic: bus.ContentUpdateRequestTopic, Data: message})
+	} else {
+		slog.WarnContext(
+			newCtx,
+			"Configuration feature disabled. Unable to process content update request",
+			"request", message, "enabled_features", cfg.Features,
+		)
+
+		err := cp.commandService.SendDataPlaneResponse(newCtx, &mpi.DataPlaneResponse{
+			MessageMeta: message.GetMessageMeta(),
+			CommandResponse: &mpi.CommandResponse{
+				Status:  mpi.CommandResponse_COMMAND_STATUS_FAILURE,
+				Message: "Content update failed",
+				Error:   "Configuration feature is disabled",
+			},
+			InstanceId: message.GetContentUpdateRequest().GetOverview().GetConfigVersion().GetInstanceId(),
+		})
+		if err != nil {
+			slog.ErrorContext(newCtx, "Unable to send data plane response", "error", err)
+		}
+	}
+}
+


question: so only check we do is check if that feature is allowed? Like is it a plus change or not?

Yeah, this is just checking that the configuration feature is enabled. It doesn't check if we're using Plus or OSS though.

sjberman · 2026-10-26T17:41:30Z

        API_ACTION_REQUEST = 5; 
        COMMAND_STATUS_REQUEST = 6; 
        UPDATE_AGENT_CONFIG_REQUEST = 7;
+        CONTENT_UPDATE_REQUEST = 8;


I'm assuming this is additive, but I want to make sure this API change is a compatible change. I'm not too familiar with protobuf APIs and what is considered additive vs breaking (this feels like additive).

@dhurley

It should be additive. The oneof in the ManagementPlaneRequest message adds content_update_request = 10 which wasn't used by any of the other messages (9 was the number before it). This also keeps it backwards compatible since receivers running on older protobufs will just ignore the field, and older senders will never send it too (so no crashes, unhandled messages)

shaun-nx added 3 commits October 22, 2026 16:25

Support ContentUpdateRequest

8c5c62f

Update bus topic

53c1b0b

make generate

f7ce488

shaun-nx requested a review from a team as a code owner October 22, 2026 16:43

github-actions Bot added chore Pull requests for routine tasks documentation Improvements or additions to documentation enhancement New feature or request labels Oct 22, 2026

shaun-nx changed the title ~~Feat/content update request~~ Add ContentUpdateRequest action to MPI Oct 22, 2026

shaun-nx mentioned this pull request Oct 22, 2026

Apply TLS certificate updates without reloads nginx/nginx-gateway-fabric#6163

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salonichf5 requested a balanced review from Copilot October 22, 2026 18:27

Copilot started reviewing on behalf of salonichf5 October 22, 2026 18:27

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Copilot AI reviewed Oct 22, 2026

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salonichf5 reviewed Oct 22, 2026

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karensantana reviewed Oct 23, 2026

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Comment thread internal/command/command_plugin.go Resolved

Comment thread internal/command/command_plugin.go Resolved

Comment thread internal/nginx/nginx_plugin.go Resolved

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sjberman reviewed Oct 26, 2026

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shaun-nx added 3 commits October 27, 2026 09:33

Resolve lint errors

7bf354d

Add new const

e0e6a8d

Merge branch 'main' into feat/content-update-request

d3604e8

Akshay2191 added the v3.x Issues and Pull Requests related to the major version v3 label Oct 29, 2026

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Add ContentUpdateRequest action to MPI - #1977

Add ContentUpdateRequest action to MPI#1977
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