add proposal for 'packagemanifests/logo' subresource

Documentation/contributors/design-proposals/operator-logos.md

@@ -0,0 +1,71 @@
+# Operator Package Logos
+
+Status: Pending
+
+Version: Alpha
+
+Implementation Owner: [@alecmerdler](github.com/alecmerdler)
+
+# Motivation
+
+Having logo icons for Operator packages is important. Currently, we include the base64-encoded representation of the image data in the `PackageManifest` API object itself. This data is not small. Even for a trivial number of Operator packages, the API response is quite large, which is a poor experience for clients. For example, a `PackageManifestList` with 65 Operators is ~1.9MB _with logos_; removing the logos reduces the size to ~450 KB.
+
+# Proposed Changes
+
+Add a new [API subresource](https://github.com/kubernetes/community/blob/master/contributors/devel/sig-architecture/api-conventions.md#types-kinds) to `PackageManifest` which serves the associated logo image file.
+
+## Implementation
+
+Add subresource following `pods/log` example in [core Kubernetes apiserver code](https://sourcegraph.com/github.com/kubernetes/kubernetes@master/-/blob/pkg/registry/core/rest/storage_core.go#L230).
+
+
+**Add subresource to both API groups:**
+
+`pkg/package-server/apiserver/generic/storage.go`
+```go
+func BuildStorage(providers *ProviderConfig) []generic.APIGroupInfo {
+	// Build storage for packages.operators.coreos.com
+	operatorInfo := generic.NewDefaultAPIGroupInfo(v1.Group, Scheme, metav1.ParameterCodec, Codecs)
+	operatorStorage := storage.NewStorage(v1.Resource("packagemanifests"), providers.Provider, Scheme)
+	logoStorage := storage.NewLogoStorage(providers.Provider)
+	operatorResources := map[string]rest.Storage{
+		"packagemanifests":      operatorStorage,
+		"packagemanifests/logo": logoStorage,
+	}
+	operatorInfo.VersionedResourcesStorageMap[v1.Version] = operatorResources
+
+	// Build storage for packages.apps.redhat.com
+	appInfo := generic.NewDefaultAPIGroupInfo(v1alpha1.Group, Scheme, metav1.ParameterCodec, Codecs)
+
+	// Use storage for package.operators.coreos.com since types are identical
+	appResources := map[string]rest.Storage{
+		"packagemanifests":      operatorStorage,
+		"packagemanifests/logo": logoStorage,
+	}
+	appInfo.VersionedResourcesStorageMap[v1alpha1.Version] = appResources
+
+	return []generic.APIGroupInfo{
+		operatorInfo,
+		appInfo,
+	}
+}
+```
+
+**Implement logo storage struct**
+
+`pkg/package-server/storage/subresources.go`
+```go
+type LogoStorage struct {
+	prov provider.PackageManifestProvider
+}
+
+var _ rest.Connecter = &LogoStorage{}
+var _ rest.StorageMetadata = &LogoStorage{}
+
+// Implement the necessary methods below...
+```
+
+# Next Stage
+
+Once the logos are being served from the subresource, console will be updated to fetch the images from those endpoints. Then we can remove the `icon` field completely from the `PackageManifest` object and benefit from the size reduction.
+