daemon: add socket ownership flags

- --socket-gid default 0 aka root with legacy alias --group
- --socket-uid default 0 aka root

cmd/daemon/daemon_linux.go

@@ -39,6 +39,7 @@ the backend to support the Docker work-alike frontend of k3c.`
  if sf, ok := flag.(cliv1.StringFlag); ok {
  sf.Value = filepath.Join(config.DefaultDaemonStateDir, "k3c.sock")
  sf.EnvVar = "K3C_ADDRESS"
+ sf.Destination = &config.Socket.Address
  app.Flags[i] = sf
  } else {
  logrus.Warnf("unexpected type for flag %q = %#v", flag.GetName(), flag)
@@ -144,6 +145,18 @@ the backend to support the Docker work-alike frontend of k3c.`
  Usage: "containerd-style image ref for sandboxes",
  Destination: &cri.Config.SandboxImage,
  },
+ cliv1.IntFlag{
+ Name: "socket-gid,group",
+ EnvVar: "K3C_SOCKET_GID",
+ Usage: "gRPC socket gid",
+ Destination: &config.Socket.GID,
+ },
+ cliv1.IntFlag{
+ Name: "socket-uid",
+ EnvVar: "K3C_SOCKET_UID",
+ Usage: "gRPC socket uid",
+ Destination: &config.Socket.UID,
+ },
  }...)
 
  app.Action = func(action interface{}) cliv1.ActionFunc {
@@ -162,6 +175,8 @@ the backend to support the Docker work-alike frontend of k3c.`
  e = t.EnvVar
  case cliv1.StringFlag:
  e = t.EnvVar
+ case cliv1.IntFlag:
+ e = t.EnvVar
  }
  if e != "" {
  if err := os.Setenv(e, clx.GlobalString(n)); err != nil {

pkg/daemon/config/config.go

@@ -9,6 +9,7 @@ import (
 
  "github.com/BurntSushi/toml"
  "github.com/containerd/containerd/platforms"
+ "github.com/containerd/containerd/services/server/config"
  buildkit "github.com/moby/buildkit/cmd/buildkitd/config"
  "github.com/rancher/k3c/pkg/defaults"
 )
@@ -28,6 +29,10 @@ var (
  DefaultVolumesDir = filepath.Join(DefaultDaemonRootDir, "volumes")
 )
 
+var (
+ Socket config.GRPCConfig
+)
+
 type K3Config struct {
  BootstrapSkip bool `toml:"bootstrap_skip"`
  BootstrapImage string `toml:"bootstrap_image"`

pkg/daemon/plugins.go

@@ -1,6 +1,9 @@
 package daemon
 
 import (
+ "os"
+ "time"
+
  "github.com/containerd/containerd/log"
  "github.com/containerd/containerd/platforms"
  "github.com/containerd/containerd/plugin"
@@ -68,5 +71,30 @@ func PluginInitFunc(ic *plugin.InitContext) (interface{}, error) {
  service := server.NewContainerService(daemon)
  service.SetInitialized(true)
  log.G(ic.Context).WithField("bridge", cfg.BridgeName).WithField("cidr", cfg.BridgeCIDR).Info("K3C daemon")
+ go func() {
+ var (
+ addr = config.Socket.Address
+ gid = config.Socket.GID
+ uid = config.Socket.UID
+ )
+ for {
+ select {
+ case <-time.After(100 * time.Millisecond):
+ err := os.Chown(addr, uid, gid)
+ if os.IsNotExist(err) {
+ continue
+ }
+ log := log.G(ic.Context).WithField("address", addr).WithField("gid", gid).WithField("uid", uid)
+ if err != nil {
+ log.WithError(err).Warn("K3C socket")
+ } else {
+ log.Debug("K3C socket")
+ }
+ return
+ case <-ic.Context.Done():
+ return
+ }
+ }
+ }()
  return service, nil
 }