libpod: forward NOTIFY_SOCKET for sd-notify container mode

Backports be5d1261b4

* mountNotifySocket consulted c.notifySocket, which was never populated.
  Use persisted c.config.SdNotifySocket instead so the path matches
  conmon's --sdnotify-socket and survives container restarts.

* Add WithSdNotifySocket and have MakeContainer read NOTIFY_SOCKET from
  the environment when sdnotify mode is container.

* Related to upstream be5d1261b4 (libpod: Move mountNotifySocket to
  container_internal_common.go), which introduced the shared
  mountNotifySocket path this wiring completes.

Created/Modified with the assistance of AI: Cursor <Auto>
Signed-off-by: Chris Evich <cevich@redhat.com>

libpod/container.go

@@ -128,10 +128,6 @@ type Container struct {
 	// This is true if a container is restored from a checkpoint.
 	restoreFromCheckpoint bool
 
-	// Used to query the NOTIFY_SOCKET once along with setting up
-	// mounts etc.
-	notifySocket string
-
 	slirp4netnsSubnet *net.IPNet
 }
 

libpod/container_internal_common.go

@@ -751,11 +751,10 @@ func lookupHostUser(name string) (*runcuser.ExecUser, error) {
 	return &execUser, nil
 }
 
-// mountNotifySocket mounts the NOTIFY_SOCKET into the container if it's set
-// and if the sdnotify mode is set to container.  It also sets c.notifySocket
-// to avoid redundantly looking up the env variable.
+// mountNotifySocket mounts the NOTIFY_SOCKET into the container if the host
+// notify socket path is stored in config and sdnotify mode is container.
 func (c *Container) mountNotifySocket(g generate.Generator) error {
-	if c.notifySocket == "" {
+	if c.config.SdNotifySocket == "" {
 		return nil
 	}
 	if c.config.SdNotifyMode != define.SdNotifyModeContainer {

libpod/options.go

@@ -626,6 +626,19 @@ func WithSdNotifyMode(mode string) CtrCreateOption {
 	}
 }
 
+// WithSdNotifySocket sets the host path to the systemd notify socket (e.g. from
+// NOTIFY_SOCKET) when using sd-notify container mode.
+func WithSdNotifySocket(socket string) CtrCreateOption {
+	return func(ctr *Container) error {
+		if ctr.valid {
+			return define.ErrCtrFinalized
+		}
+
+		ctr.config.SdNotifySocket = socket
+		return nil
+	}
+}
+
 // WithShmSize sets the size of /dev/shm tmpfs mount.
 func WithShmSize(size int64) CtrCreateOption {
 	return func(ctr *Container) error {

pkg/specgen/generate/container_create.go

@@ -7,6 +7,7 @@ import (
 	"encoding/json"
 	"errors"
 	"fmt"
+	"os"
 	"path/filepath"
 	"strings"
 
@@ -361,6 +362,11 @@ func createContainerOptions(rt *libpod.Runtime, s *specgen.SpecGenerator, pod *l
 	if len(s.SdNotifyMode) > 0 {
 		options = append(options, libpod.WithSdNotifyMode(s.SdNotifyMode))
 	}
+	if notifySocket, ok := os.LookupEnv("NOTIFY_SOCKET"); ok && notifySocket != "" {
+		if strings.EqualFold(s.SdNotifyMode, define.SdNotifyModeContainer) {
+			options = append(options, libpod.WithSdNotifySocket(notifySocket))
+		}
+	}
 	if pod != nil {
 		logrus.Debugf("adding container to pod %s", pod.Name())
 		options = append(options, rt.WithPod(pod))