Merge pull request #8998 from dmcgowan/image-inspect

ctr: images inspect

cmd/ctr/commands/images/images.go

@@ -42,6 +42,7 @@ var Command = cli.Command{
 		checkCommand,
 		exportCommand,
 		importCommand,
+		inspectCommand,
 		listCommand,
 		mountCommand,
 		unmountCommand,

cmd/ctr/commands/images/inspect.go

@@ -0,0 +1,65 @@
+/*
+   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 images
+
+import (
+	"os"
+
+	"github.com/containerd/containerd/cmd/ctr/commands"
+	"github.com/containerd/containerd/pkg/display"
+	"github.com/urfave/cli"
+)
+
+var inspectCommand = cli.Command{
+	Name:        "inspect",
+	Aliases:     []string{"i"},
+	Usage:       "inspect an image",
+	ArgsUsage:   "<image> [flags]",
+	Description: `Inspect an image`,
+	Flags: []cli.Flag{
+		cli.BoolFlag{
+			Name:  "content",
+			Usage: "Show JSON content",
+		},
+	},
+	Action: func(clicontext *cli.Context) error {
+		client, ctx, cancel, err := commands.NewClient(clicontext)
+		if err != nil {
+			return err
+		}
+		defer cancel()
+		var (
+			ref        = clicontext.Args().First()
+			imageStore = client.ImageService()
+			cs         = client.ContentStore()
+		)
+
+		img, err := imageStore.Get(ctx, ref)
+		if err != nil {
+			return err
+		}
+
+		opts := []display.PrintOpt{
+			display.WithWriter(os.Stdout),
+		}
+		if clicontext.Bool("content") {
+			opts = append(opts, display.Verbose)
+		}
+
+		return display.NewImageTreePrinter(opts...).PrintImageTree(ctx, img, cs)
+	},
+}

pkg/display/manifest_printer.go

@@ -0,0 +1,211 @@
+/*
+   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 display
+
+import (
+	"bytes"
+	"context"
+	"encoding/json"
+	"fmt"
+	"io"
+	"os"
+	"strings"
+
+	"github.com/containerd/containerd/content"
+	"github.com/containerd/containerd/images"
+	"github.com/opencontainers/go-digest"
+	ocispec "github.com/opencontainers/image-spec/specs-go/v1"
+)
+
+// TreeFormat is used to format tree based output using 4 values.
+// Each value must display with the same total width to format correctly.
+//
+// MiddleDrop is used to show a child element which is not the last child
+// LastDrop is used to show the last child element
+// SkipLine is used for displaying data from a previous child before the next child
+// Spacer is used to display child data for the last child
+type TreeFormat struct {
+	MiddleDrop string
+	LastDrop   string
+	SkipLine   string
+	Spacer     string
+}
+
+// LineTreeFormat uses line drawing characters to format a tree
+//
+// TreeRoot
+// ├── First child       # MiddleDrop =  "├── "
+// │   Skipped line      # SkipLine = "│   "
+// └── Last child        # LastDrop = "└── "
+// ....└── Only child    # Spacer="....", LastDrop = "└── "
+var LineTreeFormat = TreeFormat{
+	MiddleDrop: "├── ",
+	LastDrop:   "└── ",
+	SkipLine:   "│   ",
+	Spacer:     "    ",
+}
+
+type ContentReader interface {
+	content.Provider
+
+	Info(ctx context.Context, dgst digest.Digest) (content.Info, error)
+}
+
+type ImageTreePrinter struct {
+	verbose bool
+	w       io.Writer
+	format  TreeFormat
+}
+
+type PrintOpt func(*ImageTreePrinter)
+
+func Verbose(p *ImageTreePrinter) {
+	p.verbose = true
+}
+
+func WithWriter(w io.Writer) PrintOpt {
+	return func(p *ImageTreePrinter) {
+		p.w = w
+	}
+}
+
+func WithFormat(format TreeFormat) PrintOpt {
+	return func(p *ImageTreePrinter) {
+		p.format = format
+	}
+}
+
+func NewImageTreePrinter(opts ...PrintOpt) *ImageTreePrinter {
+	p := &ImageTreePrinter{
+		verbose: false,
+		w:       os.Stdout,
+		format:  LineTreeFormat,
+	}
+	for _, opt := range opts {
+		opt(p)
+	}
+
+	return p
+}
+
+// PrintImageTree prints an image and all its sub elements
+func (p *ImageTreePrinter) PrintImageTree(ctx context.Context, img images.Image, store ContentReader) error {
+	fmt.Fprintln(p.w, img.Name)
+	subchild := p.format.SkipLine
+	fmt.Fprintf(p.w, "%s Created: %s\n", subchild, img.CreatedAt)
+	fmt.Fprintf(p.w, "%s Updated: %s\n", subchild, img.UpdatedAt)
+	for k, v := range img.Labels {
+		fmt.Fprintf(p.w, "%s Label %q: %q\n", subchild, k, v)
+	}
+	return p.printManifestTree(ctx, img.Target, store, p.format.LastDrop, p.format.Spacer)
+}
+
+// PrintManifestTree prints a manifest and all its sub elements
+func (p *ImageTreePrinter) PrintManifestTree(ctx context.Context, desc ocispec.Descriptor, store ContentReader) error {
+	// start displaying tree from the root descriptor perspective, which is a single child view
+	return p.printManifestTree(ctx, desc, store, p.format.LastDrop, p.format.Spacer)
+}
+
+func (p *ImageTreePrinter) printManifestTree(ctx context.Context, desc ocispec.Descriptor, store ContentReader, prefix, childprefix string) error {
+	subprefix := childprefix + p.format.MiddleDrop
+	subchild := childprefix + p.format.SkipLine
+	fmt.Fprintf(p.w, "%s%s @%s (%d bytes)\n", prefix, desc.MediaType, desc.Digest, desc.Size)
+
+	if desc.Platform != nil && desc.Platform.Architecture != "" {
+		// TODO: Use containerd platform library to format
+		fmt.Fprintf(p.w, "%s Platform: %s/%s\n", subchild, desc.Platform.OS, desc.Platform.Architecture)
+	}
+	b, err := content.ReadBlob(ctx, store, desc)
+	if err != nil {
+		return err
+	}
+	if err := p.showContent(ctx, store, desc, subchild); err != nil {
+		return err
+	}
+
+	switch desc.MediaType {
+	case images.MediaTypeDockerSchema2Manifest, ocispec.MediaTypeImageManifest:
+		var manifest ocispec.Manifest
+		if err := json.Unmarshal(b, &manifest); err != nil {
+			return err
+		}
+
+		if len(manifest.Layers) == 0 {
+			subprefix = childprefix + p.format.LastDrop
+			subchild = childprefix + p.format.Spacer
+		}
+		fmt.Fprintf(p.w, "%s%s @%s (%d bytes)\n", subprefix, manifest.Config.MediaType, manifest.Config.Digest, manifest.Config.Size)
+
+		if err := p.showContent(ctx, store, manifest.Config, subchild); err != nil {
+			return err
+		}
+
+		for i := range manifest.Layers {
+			if len(manifest.Layers) == i+1 {
+				subprefix = childprefix + p.format.LastDrop
+			}
+			fmt.Fprintf(p.w, "%s%s @%s (%d bytes)\n", subprefix, manifest.Layers[i].MediaType, manifest.Layers[i].Digest, manifest.Layers[i].Size)
+		}
+
+	case images.MediaTypeDockerSchema2ManifestList, ocispec.MediaTypeImageIndex:
+		var idx ocispec.Index
+		if err := json.Unmarshal(b, &idx); err != nil {
+			return err
+		}
+
+		for i := range idx.Manifests {
+			if len(idx.Manifests) == i+1 {
+				subprefix = childprefix + p.format.LastDrop
+				subchild = childprefix + p.format.Spacer
+			}
+			if err := p.printManifestTree(ctx, idx.Manifests[i], store, subprefix, subchild); err != nil {
+				return err
+			}
+		}
+	}
+
+	return nil
+}
+
+func (p *ImageTreePrinter) showContent(ctx context.Context, store ContentReader, desc ocispec.Descriptor, prefix string) error {
+	if p.verbose {
+		info, err := store.Info(ctx, desc.Digest)
+		if err != nil {
+			return err
+		}
+		if len(info.Labels) > 0 {
+			fmt.Fprintf(p.w, "%s┌────────Labels─────────\n", prefix)
+			for k, v := range info.Labels {
+				fmt.Fprintf(p.w, "%s│%q: %q\n", prefix, k, v)
+			}
+			fmt.Fprintf(p.w, "%s└───────────────────────\n", prefix)
+		}
+	}
+	if p.verbose && strings.HasSuffix(desc.MediaType, "json") {
+		// Print content for config
+		cb, err := content.ReadBlob(ctx, store, desc)
+		if err != nil {
+			return err
+		}
+		dst := bytes.NewBuffer(nil)
+		json.Indent(dst, cb, prefix+"│", "   ")
+		fmt.Fprintf(p.w, "%s┌────────Content────────\n", prefix)
+		fmt.Fprintf(p.w, "%s│%s\n", prefix, strings.TrimSpace(dst.String()))
+		fmt.Fprintf(p.w, "%s└───────────────────────\n", prefix)
+	}
+	return nil
+}