From ef985f8628344d803d511adf12e5af7cf4606aef Mon Sep 17 00:00:00 2001
From: Akihiro Suda <akihiro.suda.cz@hco.ntt.co.jp>
Date: Sun, 10 May 2026 13:54:27 +0900
Subject: [PATCH] server: tolerate failed gRPC plugins when starting listeners

The grpc, grpc-tcp, and ttrpc server plugins enumerated their services
through ic.GetByType, which short-circuits on the first plugin whose
Instance() returned an error. A single failed gRPC plugin (e.g. CRI
under rootless, which cannot watch /etc/cni/net.d) therefore prevented
the server plugins from initialising, leaving /run/containerd/containerd.sock
uncreated.

Iterate the plugin set directly and skip plugins that failed to
initialise, restoring the pre-c15ec2485 behaviour where the listener
is still created and only the failed services are missing.

Fixes: c15ec2485 ("Add server plugins for grpc and ttrpc")
Fixes: https://github.com/containerd/containerd/issues/13362

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Signed-off-by: Akihiro Suda <akihiro.suda.cz@hco.ntt.co.jp>
---
 plugins/server/grpc/plugin.go  | 37 ++++++++++++++++++++++------------
 plugins/server/ttrpc/plugin.go | 30 +++++++++++----------------
 2 files changed, 36 insertions(+), 31 deletions(-)

diff --git a/plugins/server/grpc/plugin.go b/plugins/server/grpc/plugin.go
index 1ef44badb3..6c5b1032e5 100644
--- a/plugins/server/grpc/plugin.go
+++ b/plugins/server/grpc/plugin.go
@@ -20,7 +20,6 @@ import (
 	"context"
 	"crypto/tls"
 	"crypto/x509"
-	"errors"
 	"fmt"
 	"net"
 	"os"
@@ -112,12 +111,19 @@ func init() {
 			}
 
 			s := grpc.NewServer(serverOpts...)
-			ps, err := ic.GetByType(plugins.GRPCPlugin) // ensure grpc plugin is initialized
-			if err != nil && !errors.Is(err, plugin.ErrPluginNotFound) {
-				return nil, err
-			}
-			for _, p := range ps {
-				if gs, ok := p.(grpcService); ok {
+			// Iterate plugins directly rather than using GetByType, which
+			// short-circuits on the first plugin that failed to initialize.
+			// Plugins that failed (e.g. CRI under rootless) have already been
+			// logged and should not prevent the GRPC server from starting.
+			for _, p := range ic.Plugins().GetAll() {
+				if p.Registration.Type != plugins.GRPCPlugin {
+					continue
+				}
+				instance, err := p.Instance()
+				if err != nil {
+					continue
+				}
+				if gs, ok := instance.(grpcService); ok {
 					if err := gs.Register(s); err != nil {
 						return nil, fmt.Errorf("failed to register grpc service: %w", err)
 					}
@@ -218,13 +224,18 @@ func init() {
 			}
 
 			s := grpc.NewServer(serverOpts...)
-			ps, err := ic.GetByType(plugins.GRPCPlugin) // ensure grpc plugin is initialized
-			if err != nil && !errors.Is(err, plugin.ErrPluginNotFound) {
-				return nil, err
-			}
+			// Iterate plugins directly rather than using GetByType, which
+			// short-circuits on the first plugin that failed to initialize.
 			var hasService bool
-			for _, p := range ps {
-				if gs, ok := p.(tcpService); ok {
+			for _, p := range ic.Plugins().GetAll() {
+				if p.Registration.Type != plugins.GRPCPlugin {
+					continue
+				}
+				instance, err := p.Instance()
+				if err != nil {
+					continue
+				}
+				if gs, ok := instance.(tcpService); ok {
 					if err := gs.RegisterTCP(s); err != nil {
 						return nil, fmt.Errorf("failed to register grpc service: %w", err)
 					}
diff --git a/plugins/server/ttrpc/plugin.go b/plugins/server/ttrpc/plugin.go
index fc5f5a44d9..921538bb19 100644
--- a/plugins/server/ttrpc/plugin.go
+++ b/plugins/server/ttrpc/plugin.go
@@ -18,7 +18,6 @@ package ttrpc
 
 import (
 	"context"
-	"errors"
 	"fmt"
 	"net"
 	"os"
@@ -75,25 +74,20 @@ func init() {
 			type ttrpcService interface {
 				RegisterTTRPC(*ttrpc.Server) error
 			}
+			// Iterate plugins directly rather than using GetByType, which
+			// short-circuits on the first plugin that failed to initialize.
+			// Plugins that failed (e.g. CRI under rootless) have already been
+			// logged and should not prevent the TTRPC server from starting.
 			var hasService bool
-			ps, err := ic.GetByType(plugins.TTRPCPlugin) // ensure grpc plugin is initialized
-			if err != nil && !errors.Is(err, plugin.ErrPluginNotFound) {
-				return nil, err
-			}
-			for _, p := range ps {
-				if gs, ok := p.(ttrpcService); ok {
-					if err := gs.RegisterTTRPC(s); err != nil {
-						return nil, fmt.Errorf("failed to register ttrpc service: %w", err)
-					}
-					hasService = true
+			for _, p := range ic.Plugins().GetAll() {
+				if p.Registration.Type != plugins.TTRPCPlugin && p.Registration.Type != plugins.GRPCPlugin {
+					continue
 				}
-			}
-			ps, err = ic.GetByType(plugins.GRPCPlugin) // ensure grpc plugin is initialized
-			if err != nil && !errors.Is(err, plugin.ErrPluginNotFound) {
-				return nil, err
-			}
-			for _, p := range ps {
-				if gs, ok := p.(ttrpcService); ok {
+				instance, err := p.Instance()
+				if err != nil {
+					continue
+				}
+				if gs, ok := instance.(ttrpcService); ok {
 					if err := gs.RegisterTTRPC(s); err != nil {
 						return nil, fmt.Errorf("failed to register ttrpc service: %w", err)
 					}