fix the index append (#156)

the index append introduced in #155 created a valid index but didn't
properly append the image contents to it. instead it was simply
appending an index manifest to the index 🤦

this PR fixes that and adds another test to catch it (I think?). ideally
I'd like the test to push up a platform specific image(s) but I can't
figure out how to do that with `random.Image`.

I've at least tested this locally and it appears to be generating a
proper index:

```
{
  "schemaVersion": 2,
  "mediaType": "application/vnd.oci.image.index.v1+json",
  "manifests": [
    {
      "mediaType": "application/vnd.oci.image.manifest.v1+json",
      "size": 562,
      "digest": "sha256:c5316b34c4564257960ce18e73b6f421cae0e67c5e3cf18a97cd755947c071c4",
      "platform": {
        "architecture": "amd64",
        "os": "linux"
      }
    },
    {
      "mediaType": "application/vnd.oci.image.manifest.v1+json",
      "size": 561,
      "digest": "sha256:dad0b65b0a055bcee31b5888d5435c5f73e25785f0e92be473996fb060bb62eb",
      "platform": {
        "architecture": "arm64",
        "os": "linux"
      }
    }
  ]
}
```

Author: joshrwolf

internal/provider/append_resource.go

@@ -9,6 +9,7 @@ import (
 
 	"github.com/google/go-containerregistry/pkg/name"
 	v1 "github.com/google/go-containerregistry/pkg/v1"
+	"github.com/google/go-containerregistry/pkg/v1/empty"
 	"github.com/google/go-containerregistry/pkg/v1/mutate"
 	"github.com/google/go-containerregistry/pkg/v1/remote"
 	"github.com/google/go-containerregistry/pkg/v1/tarball"
@@ -266,9 +267,11 @@ func (r *AppendResource) doAppend(ctx context.Context, data *AppendResourceModel
 			return nil, []diag.Diagnostic{diag.NewErrorDiagnostic("Unable to read image index manifest", fmt.Sprintf("Unable to read image index manifest for ref %q, got error: %s", data.BaseImage.ValueString(), err))}
 		}
 
-		// get the image for each platform
-		for _, p := range baseimf.Manifests {
-			baseimg, err := baseidx.Image(p.Digest)
+		var idx v1.ImageIndex = empty.Index
+
+		// append to each manifest in the index
+		for _, manifest := range baseimf.Manifests {
+			baseimg, err := baseidx.Image(manifest.Digest)
 			if err != nil {
 				return nil, []diag.Diagnostic{diag.NewErrorDiagnostic("Unable to load image", fmt.Sprintf("Unable to load image for ref %q, got error: %s", data.BaseImage.ValueString(), err))}
 			}
@@ -278,17 +281,36 @@ func (r *AppendResource) doAppend(ctx context.Context, data *AppendResourceModel
 				return nil, []diag.Diagnostic{diag.NewErrorDiagnostic("Unable to append layers", fmt.Sprintf("Unable to append layers, got error: %s", err))}
 			}
 
-			baseidx = mutate.AppendManifests(baseidx, mutate.IndexAddendum{Add: img, Descriptor: p})
-
-			dig, err := baseidx.Digest()
+			imgdig, err := img.Digest()
 			if err != nil {
 				return nil, []diag.Diagnostic{diag.NewErrorDiagnostic("Unable to get image digest", fmt.Sprintf("Unable to get image digest, got error: %s", err))}
 			}
 
-			d = baseref.Context().Digest(dig.String())
-			if err := remote.WriteIndex(d, baseidx, r.popts.withContext(ctx)...); err != nil {
+			if err := remote.Write(baseref.Context().Digest(imgdig.String()), img, ropts...); err != nil {
 				return nil, []diag.Diagnostic{diag.NewErrorDiagnostic("Unable to push image", fmt.Sprintf("Unable to push image, got error: %s", err))}
 			}
+
+			// Update the index with the new image
+			idx = mutate.AppendManifests(idx, mutate.IndexAddendum{
+				Add: img,
+				Descriptor: v1.Descriptor{
+					MediaType:    manifest.MediaType,
+					URLs:         manifest.URLs,
+					Annotations:  manifest.Annotations,
+					Platform:     manifest.Platform,
+					ArtifactType: manifest.ArtifactType,
+				},
+			})
+		}
+
+		dig, err := idx.Digest()
+		if err != nil {
+			return nil, []diag.Diagnostic{diag.NewErrorDiagnostic("Unable to get index digest", fmt.Sprintf("Unable to get index digest, got error: %s", err))}
+		}
+
+		d = baseref.Context().Digest(dig.String())
+		if err := remote.WriteIndex(d, idx, ropts...); err != nil {
+			return nil, []diag.Diagnostic{diag.NewErrorDiagnostic("Unable to push index", fmt.Sprintf("Unable to push index, got error: %s", err))}
 		}
 
 	} else if desc.MediaType.IsImage() {

internal/provider/append_resource_test.go

@@ -8,6 +8,9 @@ import (
 	ocitesting "github.com/chainguard-dev/terraform-provider-oci/testing"
 	"github.com/google/go-containerregistry/pkg/crane"
 	"github.com/google/go-containerregistry/pkg/name"
+	v1 "github.com/google/go-containerregistry/pkg/v1"
+	"github.com/google/go-containerregistry/pkg/v1/empty"
+	"github.com/google/go-containerregistry/pkg/v1/mutate"
 	"github.com/google/go-containerregistry/pkg/v1/random"
 	"github.com/google/go-containerregistry/pkg/v1/remote"
 	"github.com/google/go-containerregistry/pkg/v1/validate"
@@ -138,4 +141,54 @@ func TestAccAppendResource(t *testing.T) {
 			},
 		},
 	})
+
+	ref4 := repo.Tag("4")
+	var idx2 v1.ImageIndex = empty.Index
+
+	idx2 = mutate.AppendManifests(idx2, mutate.IndexAddendum{Add: img1})
+	idx2 = mutate.AppendManifests(idx2, mutate.IndexAddendum{Add: img1})
+
+	if err := remote.WriteIndex(ref4, idx2); err != nil {
+		t.Fatalf("failed to write index: %v", err)
+	}
+
+	resource.Test(t, resource.TestCase{
+		PreCheck:                 func() { testAccPreCheck(t) },
+		ProtoV6ProviderFactories: testAccProtoV6ProviderFactories,
+		Steps: []resource.TestStep{
+			// Create and Read testing
+			{
+				Config: fmt.Sprintf(`
+resource "oci_append" "test" {
+  base_image = %q
+  layers = [{
+    files = {
+      "/usr/local/test.txt" = { contents = "hello world" }
+    }
+  }]
+}
+          `, ref4),
+				Check: resource.ComposeAggregateTestCheckFunc(
+					resource.TestCheckResourceAttr("oci_append.test", "base_image", ref4.String()),
+					resource.TestMatchResourceAttr("oci_append.test", "id", regexp.MustCompile(`/test@sha256:[0-9a-f]{64}$`)),
+					resource.TestCheckFunc(func(s *terraform.State) error {
+						rs := s.RootModule().Resources["oci_append.test"]
+						ref, err := name.ParseReference(rs.Primary.Attributes["image_ref"])
+						if err != nil {
+							return fmt.Errorf("failed to parse reference: %v", err)
+						}
+						idx, err := remote.Index(ref)
+						if err != nil {
+							return fmt.Errorf("failed to pull index: %v", err)
+						}
+						if err := validate.Index(idx); err != nil {
+							return fmt.Errorf("failed to validate index: %v", err)
+						}
+
+						return nil
+					}),
+				),
+			},
+		},
+	})
 }