introspection: expose the daemon's PID and PIDNS

Signed-off-by: Akihiro Suda <akihiro.suda.cz@hco.ntt.co.jp>

api/next.pb.txt

@@ -3472,6 +3472,20 @@ file {
       type: TYPE_STRING
       json_name: "uuid"
     }
+    field {
+      name: "pid"
+      number: 2
+      label: LABEL_OPTIONAL
+      type: TYPE_UINT64
+      json_name: "pid"
+    }
+    field {
+      name: "pidns"
+      number: 3
+      label: LABEL_OPTIONAL
+      type: TYPE_UINT64
+      json_name: "pidns"
+    }
   }
   service {
     name: "Introspection"

api/services/introspection/v1/introspection.pb.go

@@ -273,6 +273,8 @@ type ServerResponse struct {
 	unknownFields protoimpl.UnknownFields
 
 	UUID  string `protobuf:"bytes,1,opt,name=uuid,proto3" json:"uuid,omitempty"`
+	Pid   uint64 `protobuf:"varint,2,opt,name=pid,proto3" json:"pid,omitempty"`
+	Pidns uint64 `protobuf:"varint,3,opt,name=pidns,proto3" json:"pidns,omitempty"` // PID namespace, such as 4026531836
 }
 
 func (x *ServerResponse) Reset() {
@@ -314,6 +316,20 @@ func (x *ServerResponse) GetUUID() string {
 	return ""
 }
 
+func (x *ServerResponse) GetPid() uint64 {
+	if x != nil {
+		return x.Pid
+	}
+	return 0
+}
+
+func (x *ServerResponse) GetPidns() uint64 {
+	if x != nil {
+		return x.Pidns
+	}
+	return 0
+}
+
 var File_github_com_containerd_containerd_api_services_introspection_v1_introspection_proto protoreflect.FileDescriptor
 
 var file_github_com_containerd_containerd_api_services_introspection_v1_introspection_proto_rawDesc = []byte{
@@ -362,29 +378,32 @@ var file_github_com_containerd_containerd_api_services_introspection_v1_introspe
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+	0x74, 0x6f, 0x33,
 }
 
 var (

api/services/introspection/v1/introspection.proto

@@ -100,4 +100,6 @@ message PluginsResponse {
 
 message ServerResponse {
 	string uuid = 1;
+	uint64 pid = 2;
+	uint64 pidns = 3; // PID namespace, such as 4026531836
 }

cmd/ctr/app/main.go

@@ -24,6 +24,7 @@ import (
 	"github.com/containerd/containerd/cmd/ctr/commands/content"
 	"github.com/containerd/containerd/cmd/ctr/commands/events"
 	"github.com/containerd/containerd/cmd/ctr/commands/images"
+	"github.com/containerd/containerd/cmd/ctr/commands/info"
 	"github.com/containerd/containerd/cmd/ctr/commands/install"
 	"github.com/containerd/containerd/cmd/ctr/commands/leases"
 	namespacesCmd "github.com/containerd/containerd/cmd/ctr/commands/namespaces"
@@ -116,6 +117,7 @@ containerd CLI
 		install.Command,
 		ociCmd.Command,
 		sandboxes.Command,
+		info.Command,
 	}, extraCmds...)
 	app.Before = func(context *cli.Context) error {
 		if context.GlobalBool("debug") {

cmd/ctr/commands/info/info.go

@@ -0,0 +1,48 @@
+/*
+   Copyright The containerd Authors.
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package info
+
+import (
+	api "github.com/containerd/containerd/api/services/introspection/v1"
+	"github.com/containerd/containerd/cmd/ctr/commands"
+	ptypes "github.com/containerd/containerd/protobuf/types"
+	"github.com/urfave/cli"
+)
+
+type Info struct {
+	Server *api.ServerResponse `json:"server"`
+}
+
+// Command is a cli command to output the containerd server info
+var Command = cli.Command{
+	Name:  "info",
+	Usage: "print the server info",
+	Action: func(context *cli.Context) error {
+		client, ctx, cancel, err := commands.NewClient(context)
+		if err != nil {
+			return err
+		}
+		defer cancel()
+		var info Info
+		info.Server, err = client.IntrospectionService().Server(ctx, &ptypes.Empty{})
+		if err != nil {
+			return err
+		}
+		commands.PrintAsJSON(info)
+		return nil
+	},
+}

services/introspection/local.go

@@ -20,6 +20,7 @@ import (
 	context "context"
 	"os"
 	"path/filepath"
+	"runtime"
 	"sync"
 
 	api "github.com/containerd/containerd/api/services/introspection/v1"
@@ -105,8 +106,18 @@ func (l *Local) Server(ctx context.Context, _ *ptypes.Empty, _ ...grpc.CallOptio
 	if err != nil {
 		return nil, errdefs.ToGRPC(err)
 	}
+	pid := os.Getpid()
+	var pidns uint64
+	if runtime.GOOS == "linux" {
+		pidns, err = statPIDNS(pid)
+		if err != nil {
+			return nil, errdefs.ToGRPC(err)
+		}
+	}
 	return &api.ServerResponse{
 		UUID:  u,
+		Pid:   uint64(pid),
+		Pidns: pidns,
 	}, nil
 }
 

services/introspection/pidns_linux.go

@@ -0,0 +1,36 @@
+/*
+   Copyright The containerd Authors.
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package introspection
+
+import (
+	"fmt"
+	"os"
+	"syscall"
+)
+
+func statPIDNS(pid int) (uint64, error) {
+	f := fmt.Sprintf("/proc/%d/ns/pid", pid)
+	st, err := os.Stat(f)
+	if err != nil {
+		return 0, err
+	}
+	stSys, ok := st.Sys().(*syscall.Stat_t)
+	if !ok {
+		return 0, fmt.Errorf("%T is not *syscall.Stat_t", st.Sys())
+	}
+	return stSys.Ino, nil
+}

services/introspection/pidns_others.go

@@ -0,0 +1,24 @@
+//go:build !linux
+// +build !linux
+
+/*
+   Copyright The containerd Authors.
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package introspection
+
+func statPIDNS(pid int) (uint64, error) {
+	return 0, nil
+}