From 55d1abe3e8418810d40f2a4c593a9c812423fe20 Mon Sep 17 00:00:00 2001
From: Shiwei Zhang <shizh@microsoft.com>
Date: Fri, 26 Mar 2021 19:12:33 +0800
Subject: [PATCH] support artifact discovery for oras lib

Signed-off-by: Shiwei Zhang <shizh@microsoft.com>
---
 go.mod               |  2 +-
 go.sum               |  4 ++--
 pkg/oras/discover.go | 29 +++++++++++++++++++++++++++++
 3 files changed, 32 insertions(+), 3 deletions(-)
 create mode 100644 pkg/oras/discover.go

diff --git a/go.mod b/go.mod
index 6432c958e..04ee78834 100644
--- a/go.mod
+++ b/go.mod
@@ -5,7 +5,7 @@ go 1.16
 replace (
 	// WARNING! Do NOT replace these without also replacing their lines in the `require` stanza below.
 	// These `replace` stanzas are IGNORED when this is imported as a library
-	github.com/containerd/containerd => github.com/notaryproject/containerd v1.5.0-beta.4.0.20210326071533-6710065b5800
+	github.com/containerd/containerd => github.com/notaryproject/containerd v1.5.0-beta.4.0.20210326100849-6094ad5d5479
 	github.com/docker/distribution => github.com/docker/distribution v0.0.0-20191216044856-a8371794149d
 	github.com/docker/docker => github.com/moby/moby v17.12.0-ce-rc1.0.20200618181300-9dc6525e6118+incompatible
 )
diff --git a/go.sum b/go.sum
index b6dce75d0..9358575a4 100644
--- a/go.sum
+++ b/go.sum
@@ -372,8 +372,8 @@ github.com/mxk/go-flowrate v0.0.0-20140419014527-cca7078d478f/go.mod h1:ZdcZmHo+
 github.com/ncw/swift v1.0.47/go.mod h1:23YIA4yWVnGwv2dQlN4bB7egfYX6YLn0Yo/S6zZO/ZM=
 github.com/notaryproject/artifacts v0.0.0-20210325201627-49d06c9f1a07 h1:geJlhRFBwSJXhIv7KMgAXBz1Ie6wsuFeE5vuau3B4AQ=
 github.com/notaryproject/artifacts v0.0.0-20210325201627-49d06c9f1a07/go.mod h1:za0DINIIQLPCBn9AhLfPjywgT51o0zll644gbIXiQiQ=
-github.com/notaryproject/containerd v1.5.0-beta.4.0.20210326071533-6710065b5800 h1:vMfubXqR1FzRCXJDKgjpuFybJWbNVJKetJTwceky9eI=
-github.com/notaryproject/containerd v1.5.0-beta.4.0.20210326071533-6710065b5800/go.mod h1:uvn4m2BuoisfEj5I7GLoCJguWejxwLUlyM0L4XnVWY8=
+github.com/notaryproject/containerd v1.5.0-beta.4.0.20210326100849-6094ad5d5479 h1:zan+c1XrL2pyc6RuR+xYJ43SgB2AOXnLH99uAQQrn5w=
+github.com/notaryproject/containerd v1.5.0-beta.4.0.20210326100849-6094ad5d5479/go.mod h1:uvn4m2BuoisfEj5I7GLoCJguWejxwLUlyM0L4XnVWY8=
 github.com/oklog/ulid v1.3.1/go.mod h1:CirwcVhetQ6Lv90oh/F+FBtV6XMibvdAFo93nm5qn4U=
 github.com/olekukonko/tablewriter v0.0.0-20170122224234-a0225b3f23b5/go.mod h1:vsDQFd/mU46D+Z4whnwzcISnGGzXWMclvtLoiIKAKIo=
 github.com/onsi/ginkgo v0.0.0-20151202141238-7f8ab55aaf3b/go.mod h1:lLunBs/Ym6LB5Z9jYTR76FiuTmxDTDusOGeTQH+WWjE=
diff --git a/pkg/oras/discover.go b/pkg/oras/discover.go
new file mode 100644
index 000000000..496ce6ec9
--- /dev/null
+++ b/pkg/oras/discover.go
@@ -0,0 +1,29 @@
+package oras
+
+import (
+	"context"
+
+	"github.com/containerd/containerd/remotes"
+	artifactspec "github.com/notaryproject/artifacts/specs-go/v2"
+	ocispec "github.com/opencontainers/image-spec/specs-go/v1"
+)
+
+// Discover discovers artifacts referencing the specified artifact
+func Discover(ctx context.Context, resolver remotes.Resolver, ref, artifactType string) (ocispec.Descriptor, []artifactspec.Artifact, error) {
+	_, desc, err := resolver.Resolve(ctx, ref)
+	if err != nil {
+		return ocispec.Descriptor{}, nil, err
+	}
+
+	discoverer, err := resolver.Discoverer(ctx, ref)
+	if err != nil {
+		return ocispec.Descriptor{}, nil, err
+	}
+
+	artifacts, err := discoverer.Discover(ctx, desc, artifactType)
+	if err != nil {
+		return ocispec.Descriptor{}, nil, err
+	}
+
+	return desc, artifacts, err
+}