Implement GetConfiguredPlugins (#2880)

* Rework plugin loading into plugins.go and store actual plugins.

* Use constructor for new kapp_controller server.

cmd/kubeapps-apis/README.md

@@ -43,12 +43,22 @@ I0514 14:14:52.975884 1932386 server.go:129] Successfully registered plugin "/ho
 I0511 11:39:56.444553 4116647 server.go:25] Starting server on :50051
 ```
 
-You can then verify the (currently stubbed) configured plugins endpoint via http:
+You can then verify the configured plugins endpoint via http:
 
 ```bash
-curl http://localhost:50051/core/plugins/v1alpha1/configured-plugins
-
-{"plugins":["foobar.package.v1"]}
+curl -s http://localhost:50051/core/plugins/v1alpha1/configured-plugins | jq .
+{
+  "plugins": [
+    {
+      "name": "fluxv2.packages",
+      "version": "v1alpha1"
+    },
+    {
+      "name": "kapp_controller.packages",
+      "version": "v1alpha1"
+    }
+  ]
+}
 ```
 
 or via gRPC (using the [grpcurl tool](https://github.com/fullstorydev/grpcurl)):
@@ -57,7 +67,14 @@ or via gRPC (using the [grpcurl tool](https://github.com/fullstorydev/grpcurl)):
 grpcurl -plaintext localhost:50051 kubeappsapis.core.plugins.v1alpha1.PluginsService.GetConfiguredPlugins
 {
   "plugins": [
-    "foobar.package.v1"
+    {
+      "name": "fluxv2.packages",
+      "version": "v1alpha1"
+    },
+    {
+      "name": "kapp_controller.packages",
+      "version": "v1alpha1"
+    }
   ]
 }
 ```

cmd/kubeapps-apis/plugins/fluxv2/packages/v1alpha1/main.go

@@ -18,6 +18,7 @@ import (
 	"google.golang.org/grpc"
 
 	"github.com/grpc-ecosystem/grpc-gateway/v2/runtime"
+	plugins "github.com/kubeapps/kubeapps/cmd/kubeapps-apis/gen/core/plugins/v1alpha1"
 	v1alpha1 "github.com/kubeapps/kubeapps/cmd/kubeapps-apis/gen/plugins/fluxv2/packages/v1alpha1"
 )
 
@@ -31,3 +32,11 @@ func RegisterWithGRPCServer(s grpc.ServiceRegistrar) {
 func RegisterHTTPHandlerFromEndpoint(ctx context.Context, mux *runtime.ServeMux, endpoint string, opts []grpc.DialOption) error {
 	return v1alpha1.RegisterPackagesServiceHandlerFromEndpoint(ctx, mux, endpoint, opts)
 }
+
+// GetPluginDetail returns a core.plugins.Plugin describing itself.
+func GetPluginDetail() *plugins.Plugin {
+	return &plugins.Plugin{
+		Name:    "fluxv2.packages",
+		Version: "v1alpha1",
+	}
+}

cmd/kubeapps-apis/plugins/kapp_controller/packages/v1alpha1/main.go

@@ -18,16 +18,25 @@ import (
 	"google.golang.org/grpc"
 
 	"github.com/grpc-ecosystem/grpc-gateway/v2/runtime"
+	plugins "github.com/kubeapps/kubeapps/cmd/kubeapps-apis/gen/core/plugins/v1alpha1"
 	v1alpha1 "github.com/kubeapps/kubeapps/cmd/kubeapps-apis/gen/plugins/kapp_controller/packages/v1alpha1"
 )
 
 // RegisterWithGRPCServer enables a plugin to register with a gRPC server.
 func RegisterWithGRPCServer(s grpc.ServiceRegistrar) {
-	v1alpha1.RegisterPackagesServiceServer(s, &Server{})
+	v1alpha1.RegisterPackagesServiceServer(s, NewServer())
 }
 
 // RegisterHTTPHandlerFromEndpoint enables a plugin to register an http
 // handler to translate to the gRPC request.
 func RegisterHTTPHandlerFromEndpoint(ctx context.Context, mux *runtime.ServeMux, endpoint string, opts []grpc.DialOption) error {
 	return v1alpha1.RegisterPackagesServiceHandlerFromEndpoint(ctx, mux, endpoint, opts)
 }
+
+// GetPluginDetail returns a core.plugins.Plugin describing itself.
+func GetPluginDetail() *plugins.Plugin {
+	return &plugins.Plugin{
+		Name:    "kapp_controller.packages",
+		Version: "v1alpha1",
+	}
+}

cmd/kubeapps-apis/proto/kubeappsapis/core/plugins/v1alpha1/plugins.proto

@@ -7,10 +7,21 @@ import "google/api/annotations.proto";
 // The Core API service provides generic functionality shared across all
 // plugins, such as querying for enabled plugins (which can be used as a
 // liveness check). There may be other general functionality for use by all
-// plugins in the future such as creating credentials.
+// plugins in the future such as checking authz to the k8s api server using
+// the callers token.
+
+// A plugin can implement multiple services and multiple versions of a service.
+message Plugin {
+  // The name of the plugin, such as `fluxv2.packages` or `kapp_controller.packages`.
+  string name = 1;
+
+  // The version of the plugin, such as v1alpha1
+  string version = 2;
+}
+
 message GetConfiguredPluginsRequest {}
 message GetConfiguredPluginsResponse {
-  repeated string plugins = 1;
+  repeated Plugin plugins = 1;
 }
 service PluginsService {
   // GetConfiguredPlugins returns a map of short and longnames for the configured plugins.