Add support for docker URI images in buildpackstore.

buildpack_store.go

@@ -32,6 +32,11 @@ type CacheManager interface {
 	Close() error
 }
 
+//go:generate faux --interface BPStoreDockerPull --output fakes/docker_pull.go
+type BPStoreDockerPull interface {
+	Execute(string) error
+}
+
 type BuildpackStore struct {
 	Get BuildpackStoreGet
 }
@@ -71,6 +76,11 @@ func (bs BuildpackStore) WithRemoteFetcher(fetcher RemoteFetcher) BuildpackStore
 	return bs
 }
 
+func (bs BuildpackStore) WithOCIFetcher(fetcher BPStoreDockerPull) BuildpackStore {
+	bs.Get.oci = fetcher
+	return bs
+}
+
 func (bs BuildpackStore) WithCacheManager(manager CacheManager) BuildpackStore {
 	bs.Get.cacheManager = manager
 	return bs
@@ -86,12 +96,21 @@ type BuildpackStoreGet struct {
 	cacheManager CacheManager
 	local        LocalFetcher
 	remote       RemoteFetcher
+	oci          BPStoreDockerPull
 
 	offline bool
 	version string
 }
 
 func (g BuildpackStoreGet) Execute(url string) (string, error) {
+	if strings.HasPrefix(url, "docker://") {
+		if g.oci == nil {
+			return "", fmt.Errorf("must provide OCI fetcher to fetch OCI images")
+		}
+		url := strings.TrimPrefix(url, "docker://")
+		return url, g.oci.Execute(url)
+	}
+
 	err := g.cacheManager.Open()
 	if err != nil {
 		return "", fmt.Errorf("failed to open cacheManager: %s", err)

buildpack_store_test.go

@@ -21,21 +21,79 @@ func testBuildpackStore(t *testing.T, when spec.G, it spec.S) {
 		fakeRemoteFetcher *fakes.RemoteFetcher
 		fakeLocalFetcher  *fakes.LocalFetcher
 		fakeCacheManager  *fakes.CacheManager
+		fakeDockerPull    *fakes.BPStoreDockerPull
 	)
 
 	it.Before(func() {
 		fakeRemoteFetcher = &fakes.RemoteFetcher{}
 		fakeLocalFetcher = &fakes.LocalFetcher{}
 		fakeCacheManager = &fakes.CacheManager{}
+		fakeDockerPull = &fakes.BPStoreDockerPull{}
 
 		buildpackStore = occam.NewBuildpackStore()
 
 		buildpackStore = buildpackStore.WithLocalFetcher(fakeLocalFetcher).
 			WithRemoteFetcher(fakeRemoteFetcher).
-			WithCacheManager(fakeCacheManager)
+			WithCacheManager(fakeCacheManager).
+			WithOCIFetcher(fakeDockerPull)
 	})
 
 	when("getting an online buildpack", func() {
+		when("from a docker uri", func() {
+			it("returns the URI to the OCI image, stripping the docker:// protocol", func() {
+				local_url, err := buildpackStore.Get.
+					Execute("docker://some-image:tag")
+				Expect(err).NotTo(HaveOccurred())
+
+				Expect(local_url).To(Equal("some-image:tag"))
+
+				Expect(fakeDockerPull.ExecuteCall.CallCount).To(Equal(1))
+				Expect(fakeDockerPull.ExecuteCall.Receives.String).To(Equal("some-image:tag"))
+
+				Expect(fakeCacheManager.OpenCall.CallCount).To(Equal(0))
+				Expect(fakeCacheManager.CloseCall.CallCount).To(Equal(0))
+
+				Expect(fakeRemoteFetcher.GetCall.CallCount).To(Equal(0))
+				Expect(fakeLocalFetcher.GetCall.CallCount).To(Equal(0))
+			})
+
+			it("ignores the online/offline flags", func() {
+				local_url, err := buildpackStore.Get.
+					WithOfflineDependencies().
+					Execute("docker://some-image:tag")
+				Expect(err).NotTo(HaveOccurred())
+
+				Expect(local_url).To(Equal("some-image:tag"))
+
+				Expect(fakeDockerPull.ExecuteCall.CallCount).To(Equal(1))
+				Expect(fakeDockerPull.ExecuteCall.Receives.String).To(Equal("some-image:tag"))
+
+				Expect(fakeCacheManager.OpenCall.CallCount).To(Equal(0))
+				Expect(fakeCacheManager.CloseCall.CallCount).To(Equal(0))
+
+				Expect(fakeRemoteFetcher.GetCall.CallCount).To(Equal(0))
+				Expect(fakeLocalFetcher.GetCall.CallCount).To(Equal(0))
+			})
+
+			it("ignores the version flag", func() {
+				local_url, err := buildpackStore.Get.
+					WithVersion("some-version").
+					Execute("docker://some-image:tag")
+				Expect(err).NotTo(HaveOccurred())
+
+				Expect(local_url).To(Equal("some-image:tag"))
+
+				Expect(fakeDockerPull.ExecuteCall.CallCount).To(Equal(1))
+				Expect(fakeDockerPull.ExecuteCall.Receives.String).To(Equal("some-image:tag"))
+
+				Expect(fakeCacheManager.OpenCall.CallCount).To(Equal(0))
+				Expect(fakeCacheManager.CloseCall.CallCount).To(Equal(0))
+
+				Expect(fakeRemoteFetcher.GetCall.CallCount).To(Equal(0))
+				Expect(fakeLocalFetcher.GetCall.CallCount).To(Equal(0))
+			})
+		})
+
 		when("from a local uri", func() {
 			it.Before(func() {
 				fakeLocalFetcher.GetCall.Returns.String = "/path/to/cool-buildpack/"
@@ -151,6 +209,18 @@ func testBuildpackStore(t *testing.T, when spec.G, it spec.S) {
 	})
 
 	when("failure cases", func() {
+		when("attempting to fetch OCI image without OCI fetcher", func() {
+			it.Before(func() {
+				buildpackStore = occam.NewBuildpackStore()
+			})
+
+			it("returns an error", func() {
+				_, err := buildpackStore.Get.Execute("docker://some-image:tag")
+
+				Expect(err).To(MatchError("must provide OCI fetcher to fetch OCI images"))
+			})
+		})
+
 		when("unable to open cacheManager", func() {
 			it.Before(func() {
 				fakeCacheManager.OpenCall.Returns.Error = errors.New("bad bad error")

fakes/docker_pull.go

@@ -0,0 +1,28 @@
+package fakes
+
+import "sync"
+
+type BPStoreDockerPull struct {
+	ExecuteCall struct {
+		mutex     sync.Mutex
+		CallCount int
+		Receives  struct {
+			String string
+		}
+		Returns struct {
+			Error error
+		}
+		Stub func(string) error
+	}
+}
+
+func (f *BPStoreDockerPull) Execute(param1 string) error {
+	f.ExecuteCall.mutex.Lock()
+	defer f.ExecuteCall.mutex.Unlock()
+	f.ExecuteCall.CallCount++
+	f.ExecuteCall.Receives.String = param1
+	if f.ExecuteCall.Stub != nil {
+		return f.ExecuteCall.Stub(param1)
+	}
+	return f.ExecuteCall.Returns.Error
+}