feat: answer ECR DescribeRegistry with the caller's registry and an empty replication configuration (#1182)

docs/coverage/README.md

@@ -17,13 +17,13 @@ tags:
 
 ## Overview
 
-The platform serves **391 operations** across the AWS APIs below. Every page names the operations its service implements from the pinned model, generated from the dispatch tables on each build rather than written by hand.
+The platform serves **392 operations** across the AWS APIs below. Every page names the operations its service implements from the pinned model, generated from the dispatch tables on each build rather than written by hand.
 
 | Service | Operations |
 |---|---:|
 | [ACM](/coverage/acm) | 9 |
 | [EC2](/coverage/ec2) | 127 |
-| [ECR](/coverage/ecr) | 22 |
+| [ECR](/coverage/ecr) | 23 |
 | [ECS](/coverage/ecs) | 31 |
 | [EKS](/coverage/eks) | 27 |
 | [ELBv2](/coverage/elbv2) | 36 |
@@ -31,4 +31,4 @@ The platform serves **391 operations** across the AWS APIs below. Every page nam
 | [RDS](/coverage/rds) | 27 |
 | [S3](/coverage/s3) | 26 |
 | [STS](/coverage/sts) | 5 |
-| **Total** | **391** |
+| **Total** | **392** |

docs/coverage/coverage.json

@@ -1983,6 +1983,7 @@
           "DeleteRepository",
           "DeleteRepositoryPolicy",
           "DescribeImages",
+          "DescribeRegistry",
           "DescribeRepositories",
           "GetAuthorizationToken",
           "GetLifecyclePolicy",
@@ -2002,7 +2003,6 @@
         "stubbed": [
           "BatchCheckLayerAvailability",
           "CompleteLayerUpload",
-          "DescribeRegistry",
           "GetDownloadUrlForLayer",
           "GetRegistryPolicy",
           "InitiateLayerUpload",

docs/coverage/ecr/README.md

@@ -18,7 +18,7 @@ tags:
 
 ## Overview
 
-Spinifex implements **22 operations** in the ECR `2015-09-21` API model.
+Spinifex implements **23 operations** in the ECR `2015-09-21` API model.
 
 ### Two endpoints, one registry
 
@@ -26,7 +26,7 @@ Repository metadata is served over the AWS API on the gateway endpoint. Image da
 
 The split explains the stubs below. The layer-transfer operations — `BatchCheckLayerAvailability`, `InitiateLayerUpload`, `UploadLayerPart`, `CompleteLayerUpload` and `GetDownloadUrlForLayer` — are registered stubs because the `/v2/` endpoint carries that traffic instead. A client using `docker` or any OCI-compatible tool never calls them.
 
-Registry replication is a stub for the same kind of reason: a deployment is a single registry, with no cross-region peer to replicate to.
+Registry replication is a stub for the same kind of reason: a deployment is a single registry, with no cross-region peer to replicate to. `DescribeRegistry` reports this as a replication configuration with no rules.
 
 ### Operations
 
@@ -39,6 +39,7 @@ Registry replication is a stub for the same kind of reason: a deployment is a si
 | `DeleteRepository` |
 | `DeleteRepositoryPolicy` |
 | `DescribeImages` |
+| `DescribeRegistry` |
 | `DescribeRepositories` |
 | `GetAuthorizationToken` |
 | `GetLifecyclePolicy` |

docs/coverage/ecr/intro.md

@@ -4,4 +4,4 @@ Repository metadata is served over the AWS API on the gateway endpoint. Image da
 
 The split explains the stubs below. The layer-transfer operations — `BatchCheckLayerAvailability`, `InitiateLayerUpload`, `UploadLayerPart`, `CompleteLayerUpload` and `GetDownloadUrlForLayer` — are registered stubs because the `/v2/` endpoint carries that traffic instead. A client using `docker` or any OCI-compatible tool never calls them.
 
-Registry replication is a stub for the same kind of reason: a deployment is a single registry, with no cross-region peer to replicate to.
+Registry replication is a stub for the same kind of reason: a deployment is a single registry, with no cross-region peer to replicate to. `DescribeRegistry` reports this as a replication configuration with no rules.

docs/coverage/internal-report.md

@@ -762,7 +762,7 @@ spot-price: On owned hardware there is no spot-to-on-demand price differential,
 
 ## ecr
 
-`2015-09-21` — 22 of 58 modelled operations implemented (37.9%), 11 stubbed, 0 not applicable, 3 registered outside the pinned model.
+`2015-09-21` — 23 of 58 modelled operations implemented (39.7%), 10 stubbed, 0 not applicable, 3 registered outside the pinned model.
 
 ### Not implemented
 
@@ -793,7 +793,6 @@ spot-price: On owned hardware there is no spot-to-on-demand price differential,
 
 - `BatchCheckLayerAvailability`
 - `CompleteLayerUpload`
-- `DescribeRegistry`
 - `GetDownloadUrlForLayer`
 - `GetRegistryPolicy`
 - `InitiateLayerUpload`

spinifex/gateway/ecrapi/handler.go

@@ -79,7 +79,7 @@ var Actions = map[string]Handler{
 	"DeleteRepositoryPolicy": DeleteRepositoryPolicy,
 	"GetRegistryPolicy":      NotImplemented,
 	"PutRegistryPolicy":      NotImplemented,
-	"DescribeRegistry":       NotImplemented,
+	"DescribeRegistry":       DescribeRegistry,
 
 	// Image scanning is unsupported (no scanner backend), except that
 	// PutImageScanningConfiguration accepts the scanOnPush=false no-op rather

spinifex/gateway/ecrapi/registry.go

@@ -0,0 +1,28 @@
+package gateway_ecrapi
+
+import (
+	"context"
+	"encoding/json"
+
+	"github.com/aws/aws-sdk-go/aws"
+	"github.com/aws/aws-sdk-go/service/ecr"
+	"github.com/nats-io/nats.go"
+)
+
+// DescribeRegistry reports the caller's registry. A deployment has no
+// replication, so the configuration is always present with an empty rules
+// list, which is what AWS returns for an account with none configured.
+func DescribeRegistry(_ context.Context, _ *nats.Conn, accountID string, body []byte) (any, error) {
+	if len(body) > 0 {
+		var req struct{}
+		if err := json.Unmarshal(body, &req); err != nil {
+			return nil, MalformedBodyError()
+		}
+	}
+	return &ecr.DescribeRegistryOutput{
+		RegistryId: aws.String(accountID),
+		ReplicationConfiguration: &ecr.ReplicationConfiguration{
+			Rules: []*ecr.ReplicationRule{},
+		},
+	}, nil
+}

spinifex/gateway/ecrapi/registry_test.go

@@ -0,0 +1,63 @@
+package gateway_ecrapi_test
+
+import (
+	"context"
+	"encoding/json"
+	"net/http/httptest"
+	"testing"
+
+	"github.com/mulgadc/spinifex/spinifex/awserrors"
+	gateway_ecrapi "github.com/mulgadc/spinifex/spinifex/gateway/ecrapi"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+// describeRegistryWire runs the dispatched DescribeRegistry handler and
+// serialises its output the way the gateway does, returning the decoded body.
+func describeRegistryWire(t *testing.T, accountID string, body []byte) map[string]any {
+	t.Helper()
+	out, err := gateway_ecrapi.Actions["DescribeRegistry"](context.Background(), nil, accountID, body)
+	require.NoError(t, err)
+	w := httptest.NewRecorder()
+	gateway_ecrapi.WriteJSONResponse(w, out)
+	var decoded map[string]any
+	require.NoError(t, json.Unmarshal(w.Body.Bytes(), &decoded))
+	return decoded
+}
+
+// AWS answers an account with no replication with the configuration present
+// and an empty rules list, not with the configuration omitted.
+func TestDescribeRegistry_CallerAccountAndEmptyReplication(t *testing.T) {
+	for _, body := range []string{"", "{}", "null"} {
+		t.Run("body="+body, func(t *testing.T) {
+			decoded := describeRegistryWire(t, "123456789012", []byte(body))
+			assert.Equal(t, map[string]any{
+				"registryId":               "123456789012",
+				"replicationConfiguration": map[string]any{"rules": []any{}},
+			}, decoded)
+		})
+	}
+}
+
+func TestDescribeRegistry_ScopedToCaller(t *testing.T) {
+	a := describeRegistryWire(t, "111111111111", nil)
+	b := describeRegistryWire(t, "222222222222", nil)
+	assert.Equal(t, "111111111111", a["registryId"])
+	assert.Equal(t, "222222222222", b["registryId"])
+}
+
+func TestDescribeRegistry_MalformedBody(t *testing.T) {
+	for _, body := range []string{"{", "[]", `"x"`} {
+		t.Run(body, func(t *testing.T) {
+			out, err := gateway_ecrapi.DescribeRegistry(context.Background(), nil, "123456789012", []byte(body))
+			assert.Nil(t, out)
+			require.Error(t, err)
+			assert.Equal(t, awserrors.ValidErrorCodeFromError(gateway_ecrapi.MalformedBodyError()),
+				awserrors.ValidErrorCodeFromError(err))
+		})
+	}
+}
+
+func TestDescribeRegistry_NotStubbed(t *testing.T) {
+	assert.NotContains(t, gateway_ecrapi.StubbedActionNames(), "DescribeRegistry")
+}