platformd: mount socket parent dir instead of direct path

platformd/checkpoint/service.go

@@ -278,16 +278,11 @@ func (s *ServiceImpl) checkpoint(ctx context.Context, id string, baseRef name.Re
 		return fmt.Errorf("kill sockets: %w", err)
 	}
 
-	// immediately checkpointing after canceling the attach stream in waitContainerReady
-	// leads to this error consistently appearing:
+	// wait a little after closing all sockets, as it seems that if we directly checkpoint we still get:
 	//
 	//		Error (criu/sk-inet.c:191): inet: Connected TCP socket, consider using --tcp-established option.
 	//
-	// the problem is, that there seems to be an open tcp connection which blocks criu
-	// from checkpointing. i don't know where this is coming from, my workaround for
-	// now is to just wait a bit.
-	// FIXME: possible solution could be to cut internet access after the server has
-	// initialized.
+	// linux might take some time to close all sockets eventually.
 	time.Sleep(s.cfg.WaitAfterServerInit)
 
 	logger.InfoContext(ctx, "checkpointing container", "container_id", ctrID)

platformd/server.go

@@ -293,8 +293,14 @@ func (s *Server) Run(ctx context.Context, cfg Config) error {
 					ContainerPath: "/etc/envoy/config.yaml",
 				},
 				{
-					HostPath:      cfg.ManagementServerListenSock.Path,
-					ContainerPath: cfg.ManagementServerListenSock.Path,
+					// mount the parent dir of the socket instead of the socket
+					// path directly, because if platformd restarts the socket
+					// mount will go stale as the socket is closed. this causes
+					// all clients requests to fail until we restart the container.
+					// the parent dir will still be present, if platformd is stopped.
+					// once it's back up clients can access the socket again.
+					HostPath:      filepath.Dir(cfg.ManagementServerListenSock.Path),
+					ContainerPath: filepath.Dir(cfg.ManagementServerListenSock.Path),
 				},
 			},
 			Linux: &runtimev1.LinuxContainerConfig{

platformd/workload/service.go

@@ -174,8 +174,14 @@ func (s *svc) RunWorkload(ctx context.Context, w Workload, attempt uint) error {
 			LogPath: "servermon.slog",
 			Mounts: []*runtimev1.Mount{
 				{
-					HostPath:      s.cfg.PlatformdListenSockURL.Path,
-					ContainerPath: s.cfg.PlatformdListenSockURL.Path,
+					// mount the parent dir of the socket instead of the socket
+					// path directly, because if platformd restarts the socket
+					// mount will go stale as the socket is closed. this causes
+					// all clients requests to fail until we restart the container.
+					// the parent dir will still be present, if platformd is stopped.
+					// once it's back up clients can access the socket again.
+					HostPath:      filepath.Dir(s.cfg.PlatformdListenSockURL.Path),
+					ContainerPath: filepath.Dir(s.cfg.PlatformdListenSockURL.Path),
 				},
 			},
 			Linux: &runtimev1.LinuxContainerConfig{

platformd/workload/service_test.go

@@ -23,6 +23,7 @@ import (
 	"fmt"
 	"log/slog"
 	"os"
+	"path/filepath"
 	"strings"
 	"testing"
 
@@ -144,8 +145,8 @@ func TestRunWorkload(t *testing.T) {
 							LogPath: "servermon.slog",
 							Mounts: []*runtimev1.Mount{
 								{
-									HostPath:      cfg.PlatformdListenSockURL.Path,
-									ContainerPath: cfg.PlatformdListenSockURL.Path,
+									HostPath:      filepath.Dir(cfg.PlatformdListenSockURL.Path),
+									ContainerPath: filepath.Dir(cfg.PlatformdListenSockURL.Path),
 								},
 							},
 							Linux: &runtimev1.LinuxContainerConfig{