Merging artifacts Branch: Add discover comand

cmd/oras/discover.go

@@ -0,0 +1,179 @@
+package main
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"os"
+	"strings"
+
+	"oras.land/oras-go/v2/registry/remote"
+	"oras.land/oras/cmd/oras/internal/option"
+
+	"github.com/need-being/go-tree"
+	digest "github.com/opencontainers/go-digest"
+	ocispec "github.com/opencontainers/image-spec/specs-go/v1"
+	artifactspec "github.com/oras-project/artifacts-spec/specs-go/v1"
+	"github.com/spf13/cobra"
+)
+
+type discoverOptions struct {
+	option.Common
+	option.Remote
+
+	targetRef    string
+	artifactType string
+	outputType   string
+}
+
+func discoverCmd() *cobra.Command {
+	var opts discoverOptions
+	cmd := &cobra.Command{
+		Use:   "discover [options] <name:tag|name@digest>",
+		Short: "discover artifacts from remote registry",
+		Long: `discover artifacts from remote registry
+
+Example - Discover all the artifacts linked with the specified reference:
+  oras discover localhost:5000/hello
+
+Example - Discover all the artifacts linked with the specified reference in a tree view:
+  oras discover localhost:5000/hello -o tree
+
+Example - Discover artifacts of type test-artifact test-artifact linked with the specified reference:
+  oras discover --artifact test-artifact localhost:5000/hello
+`,
+		Args: cobra.ExactArgs(1),
+		PreRun: func(cmd *cobra.Command, args []string) {
+			fmt.Println("Command discover is experimental and under development.")
+		},
+		RunE: func(cmd *cobra.Command, args []string) error {
+			opts.targetRef = args[0]
+			return runDiscover(opts)
+		},
+	}
+
+	cmd.Flags().StringVarP(&opts.artifactType, "artifact-type", "", "", "artifact type")
+	cmd.Flags().StringVarP(&opts.outputType, "output", "o", "table", fmt.Sprintf("Format in which to display references (%s, %s, or %s). tree format will show all references including nested", "table", "json", "tree"))
+	option.ApplyFlags(&opts, cmd.Flags())
+	return cmd
+}
+
+func runDiscover(opts discoverOptions) error {
+	ctx, _ := opts.SetLoggerLevel()
+	repo, err := opts.NewRepository(opts.targetRef, opts.Common)
+	if err != nil {
+		return err
+	}
+
+	// discover artifacts
+	root := tree.New(opts.targetRef)
+	desc, err := repo.Resolve(ctx, repo.Reference.Reference)
+	if err != nil {
+		return err
+	}
+	desc, refs, err := getAllReferences(ctx, repo, desc, opts.artifactType, root, opts.outputType == "tree")
+	if err != nil {
+		return err
+	}
+
+	switch opts.outputType {
+	case "tree":
+		tree.Print(root)
+	case "json":
+		printDiscoveredReferencesJSON(desc, *refs)
+	default:
+		fmt.Println("Discovered", len(*refs), "artifacts referencing", opts.targetRef)
+		fmt.Println("Digest:", desc.Digest)
+
+		if len(*refs) != 0 {
+			fmt.Println()
+			printDiscoveredReferencesTable(*refs, opts.Verbose)
+		}
+	}
+	return nil
+}
+
+func getAllReferences(ctx context.Context, repo *remote.Repository, desc ocispec.Descriptor, artifactType string, node *tree.Node, queryGraph bool) (ocispec.Descriptor, *[]artifactspec.Descriptor, error) {
+	var results []artifactspec.Descriptor
+	err := repo.Referrers(ctx, desc, func(referrers []artifactspec.Descriptor) error {
+		for _, r := range referrers {
+			if artifactType == "" || artifactType == r.ArtifactType {
+				results = append(results, r)
+				if !queryGraph {
+					continue
+				}
+				// Find all referrers
+				referrerNode := node.AddPath(r.ArtifactType, r.Digest)
+				_, nestedReferrers, err := getAllReferences(
+					ctx, repo,
+					ocispec.Descriptor{
+						Digest:    r.Digest,
+						Size:      r.Size,
+						MediaType: r.MediaType,
+					},
+					artifactType, referrerNode, queryGraph)
+				if err != nil {
+					return err
+				}
+				results = append(results, *nestedReferrers...)
+			}
+		}
+		return nil
+	})
+	if err != nil {
+		return ocispec.Descriptor{}, nil, err
+	}
+	return desc, &results, nil
+}
+
+func printDiscoveredReferencesTable(refs []artifactspec.Descriptor, verbose bool) {
+	typeNameTitle := "Artifact Type"
+	typeNameLength := len(typeNameTitle)
+	for _, ref := range refs {
+		if length := len(ref.ArtifactType); length > typeNameLength {
+			typeNameLength = length
+		}
+	}
+
+	print := func(key string, value interface{}) {
+		fmt.Println(key, strings.Repeat(" ", typeNameLength-len(key)+1), value)
+	}
+
+	print(typeNameTitle, "Digest")
+	for _, ref := range refs {
+		print(ref.ArtifactType, ref.Digest)
+		if verbose {
+			printJSON(ref)
+		}
+	}
+}
+
+func printDiscoveredReferencesJSON(desc ocispec.Descriptor, refs []artifactspec.Descriptor) {
+	type reference struct {
+		Digest   digest.Digest `json:"digest"`
+		Artifact string        `json:"artifactType"`
+	}
+	output := struct {
+		Digest     digest.Digest `json:"digest"`
+		References []reference   `json:"references"`
+	}{
+		Digest:     desc.Digest,
+		References: make([]reference, len(refs)),
+	}
+
+	for i, ref := range refs {
+		output.References[i] = reference{
+			Digest:   ref.Digest,
+			Artifact: ref.ArtifactType,
+		}
+	}
+
+	printJSON(output)
+}
+
+func printJSON(object interface{}) {
+	encoder := json.NewEncoder(os.Stdout)
+	encoder.SetEscapeHTML(false)
+	encoder.SetIndent("", "  ")
+	encoder.Encode(object)
+}

cmd/oras/main.go

@@ -11,7 +11,7 @@ func main() {
 		Use:          "oras [command]",
 		SilenceUsage: true,
 	}
-	cmd.AddCommand(pullCmd(), pushCmd(), loginCmd(), logoutCmd(), versionCmd())
+	cmd.AddCommand(pullCmd(), pushCmd(), loginCmd(), logoutCmd(), versionCmd(), discoverCmd())
 	if err := cmd.Execute(); err != nil {
 		os.Exit(1)
 	}

go.mod

@@ -5,8 +5,10 @@ go 1.18
 require (
 	github.com/docker/cli v20.10.17+incompatible
 	github.com/moby/term v0.0.0-20210619224110-3f7ff695adc6
+	github.com/need-being/go-tree v0.1.0
 	github.com/opencontainers/go-digest v1.0.0
 	github.com/opencontainers/image-spec v1.0.3-0.20211202183452-c5a74bcca799
+	github.com/oras-project/artifacts-spec v1.0.0-rc.1
 	github.com/sirupsen/logrus v1.8.1
 	github.com/spf13/cobra v1.5.0
 	github.com/spf13/pflag v1.0.5
@@ -18,7 +20,6 @@ require (
 	github.com/docker/docker v20.10.17+incompatible // indirect
 	github.com/docker/docker-credential-helpers v0.6.4 // indirect
 	github.com/inconshreveable/mousetrap v1.0.0 // indirect
-	github.com/oras-project/artifacts-spec v1.0.0-draft.1.1 // indirect
 	github.com/pkg/errors v0.9.1 // indirect
 	golang.org/x/sync v0.0.0-20210220032951-036812b2e83c // indirect
 	golang.org/x/sys v0.0.0-20210616094352-59db8d763f22 // indirect

go.sum

@@ -20,12 +20,14 @@ github.com/inconshreveable/mousetrap v1.0.0 h1:Z8tu5sraLXCXIcARxBp/8cbvlwVa7Z1NH
 github.com/inconshreveable/mousetrap v1.0.0/go.mod h1:PxqpIevigyE2G7u3NXJIT2ANytuPF1OarO4DADm73n8=
 github.com/moby/term v0.0.0-20210619224110-3f7ff695adc6 h1:dcztxKSvZ4Id8iPpHERQBbIJfabdt4wUm5qy3wOL2Zc=
 github.com/moby/term v0.0.0-20210619224110-3f7ff695adc6/go.mod h1:E2VnQOmVuvZB6UYnnDB0qG5Nq/1tD9acaOpo6xmt0Kw=
+github.com/need-being/go-tree v0.1.0 h1:blQrtD006cFm97UDeMUfixwPc9o06A6c+uLaUskdNNw=
+github.com/need-being/go-tree v0.1.0/go.mod h1:UOHUchuOm+lxM+EtvQ9h/IO88hK/ke7FHai4oGhhEoI=
 github.com/opencontainers/go-digest v1.0.0 h1:apOUWs51W5PlhuyGyz9FCeeBIOUDA/6nW8Oi/yOhh5U=
 github.com/opencontainers/go-digest v1.0.0/go.mod h1:0JzlMkj0TRzQZfJkVvzbP0HBR3IKzErnv2BNG4W4MAM=
 github.com/opencontainers/image-spec v1.0.3-0.20211202183452-c5a74bcca799 h1:rc3tiVYb5z54aKaDfakKn0dDjIyPpTtszkjuMzyt7ec=
 github.com/opencontainers/image-spec v1.0.3-0.20211202183452-c5a74bcca799/go.mod h1:BtxoFyWECRxE4U/7sNtV5W15zMzWCbyJoFRP3s7yZA0=
-github.com/oras-project/artifacts-spec v1.0.0-draft.1.1 h1:2YMUDyDH0glYA4gNG/zEg9HNVzgGX8kr/NBLR9AQkLQ=
-github.com/oras-project/artifacts-spec v1.0.0-draft.1.1/go.mod h1:Xch2aLzSwtkhbFFN6LUzTfLtukYvMMdXJ4oZ8O7BOdc=
+github.com/oras-project/artifacts-spec v1.0.0-rc.1 h1:bCHf9mPbrgiNwQFyVzBX79BYZVAl0OUrmvICZOCOwts=
+github.com/oras-project/artifacts-spec v1.0.0-rc.1/go.mod h1:Xch2aLzSwtkhbFFN6LUzTfLtukYvMMdXJ4oZ8O7BOdc=
 github.com/pkg/errors v0.8.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
 github.com/pkg/errors v0.9.1 h1:FEBLx1zS214owpjy7qsBeixbURkuhQAwrK5UwLGTwt4=
 github.com/pkg/errors v0.9.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=