ctr: new deprecations command

Signed-off-by: Samuel Karp <samuelkarp@google.com>
(cherry picked from commit 3fff8b4)
Signed-off-by: Samuel Karp <samuelkarp@google.com>

cmd/ctr/app/main.go

@@ -22,6 +22,7 @@ import (
 
 	"github.com/containerd/containerd/cmd/ctr/commands/containers"
 	"github.com/containerd/containerd/cmd/ctr/commands/content"
+	"github.com/containerd/containerd/cmd/ctr/commands/deprecations"
 	"github.com/containerd/containerd/cmd/ctr/commands/events"
 	"github.com/containerd/containerd/cmd/ctr/commands/images"
 	"github.com/containerd/containerd/cmd/ctr/commands/install"
@@ -114,6 +115,7 @@ containerd CLI
 		tasks.Command,
 		install.Command,
 		ociCmd.Command,
+		deprecations.Command,
 	}, extraCmds...)
 	app.Before = func(context *cli.Context) error {
 		if context.GlobalBool("debug") {

cmd/ctr/commands/deprecations/deprecations.go

@@ -0,0 +1,112 @@
+/*
+   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 deprecations
+
+import (
+	"fmt"
+	"os"
+	"text/tabwriter"
+	"time"
+
+	ptypes "github.com/gogo/protobuf/types"
+	"github.com/urfave/cli"
+
+	api "github.com/containerd/containerd/api/services/introspection/v1"
+	"github.com/containerd/containerd/cmd/ctr/commands"
+)
+
+// Command is the parent for all commands under "deprecations"
+var Command = cli.Command{
+	Name: "deprecations",
+	Subcommands: []cli.Command{
+		listCommand,
+	},
+}
+var listCommand = cli.Command{
+	Name:  "list",
+	Usage: "Print warnings for deprecations",
+	Flags: []cli.Flag{
+		cli.StringFlag{
+			Name:  "format",
+			Usage: "output format to use (Examples: 'default', 'json')",
+		},
+	},
+	Action: func(context *cli.Context) error {
+		client, ctx, cancel, err := commands.NewClient(context)
+		if err != nil {
+			return err
+		}
+		defer cancel()
+
+		resp, err := client.IntrospectionService().Server(ctx, &ptypes.Empty{})
+		if err != nil {
+			return err
+		}
+		wrn := warnings(resp)
+		if len(wrn) > 0 {
+			switch context.String("format") {
+			case "json":
+				commands.PrintAsJSON(warnings(resp))
+				return nil
+			default:
+				w := tabwriter.NewWriter(os.Stdout, 4, 8, 4, ' ', 0)
+				fmt.Fprintln(w, "ID\tLAST OCCURRENCE\tMESSAGE\t")
+				for _, dw := range wrn {
+					if _, err := fmt.Fprintf(w, "%s\t%s\t%s\n",
+						dw.ID,
+						dw.LastOccurrence.Format(time.RFC3339Nano),
+						dw.Message,
+					); err != nil {
+						return err
+					}
+				}
+				return w.Flush()
+			}
+
+		}
+		return nil
+	},
+}
+
+type deprecationWarning struct {
+	ID             string    `json:"id"`
+	Message        string    `json:"message"`
+	LastOccurrence time.Time `json:"lastOccurrence"`
+}
+
+func warnings(in *api.ServerResponse) []deprecationWarning {
+	var warnings []deprecationWarning
+	for _, dw := range in.Deprecations {
+		wrn := deprecationWarningFromPB(dw)
+		if wrn == nil {
+			continue
+		}
+		warnings = append(warnings, *wrn)
+	}
+	return warnings
+}
+func deprecationWarningFromPB(in *api.DeprecationWarning) *deprecationWarning {
+	if in == nil {
+		return nil
+	}
+	lo, _ := ptypes.TimestampFromProto(in.LastOccurrence)
+	return &deprecationWarning{
+		ID:             in.ID,
+		Message:        in.Message,
+		LastOccurrence: lo,
+	}
+}