feat: add a grpc plugin system

cmd/switcher/switcher.go

@@ -316,6 +316,15 @@ func initialize() ([]storetypes.KubeconfigStore, *types.Config, error) {
 				return nil, nil, err
 			}
 			s = capiStore
+		case types.StoreKindPlugin:
+			pluginStore, err := store.NewPluginStore(kubeconfigStoreFromConfig)
+			if err != nil {
+				if kubeconfigStoreFromConfig.Required != nil && !*kubeconfigStoreFromConfig.Required {
+					continue
+				}
+				return nil, nil, err
+			}
+			s = pluginStore
 		default:
 			return nil, nil, fmt.Errorf("unknown store %q", kubeconfigStoreFromConfig.Kind)
 		}

pkg/store/kubeconfig_store_plugins.go

@@ -0,0 +1,153 @@
+// Copyright 2024 The Kubeswitch authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package store
+
+import (
+	"context"
+	"fmt"
+	"os/exec"
+
+	"github.com/hashicorp/go-plugin"
+	"github.com/sirupsen/logrus"
+	"gopkg.in/yaml.v3"
+
+	"github.com/danielfoehrkn/kubeswitch/pkg/store/plugins"
+	storetypes "github.com/danielfoehrkn/kubeswitch/pkg/store/types"
+	"github.com/danielfoehrkn/kubeswitch/types"
+)
+
+func NewPluginStore(store types.KubeconfigStore) (*PluginStore, error) {
+	storePlugin := &types.StoreConfigPlugin{}
+	if store.Config != nil {
+		buf, err := yaml.Marshal(store.Config)
+		if err != nil {
+			return nil, fmt.Errorf("failed to process plugin store config: %w", err)
+		}
+
+		err = yaml.Unmarshal(buf, storePlugin)
+		if err != nil {
+			return nil, fmt.Errorf("failed to unmarshal plugin config: %w", err)
+		}
+	}
+
+	return &PluginStore{
+		Logger:          logrus.New().WithField("store", types.StoreKindPlugin),
+		KubeconfigStore: store,
+		Config:          storePlugin,
+	}, nil
+}
+
+// InitializePluginStore initializes the plugin store
+func (s *PluginStore) InitializePluginStore() error {
+
+	client := plugin.NewClient(&plugin.ClientConfig{
+		HandshakeConfig: plugins.Handshake,
+		Plugins:         plugins.PluginMap,
+		Cmd:             exec.Command(s.Config.CmdPath, s.Config.Args...),
+		AllowedProtocols: []plugin.Protocol{
+			plugin.ProtocolNetRPC, plugin.ProtocolGRPC},
+	})
+
+	// Connect via RPC
+	rpcClient, err := client.Client()
+	if err != nil {
+		return err
+	}
+
+	plugin, err := rpcClient.Dispense("store")
+	if err != nil {
+		return fmt.Errorf("failed to dispense plugin: %w", err)
+	}
+
+	c, ok := plugin.(plugins.Store)
+	if !ok {
+		return fmt.Errorf("plugin does not implement Store interface")
+	}
+
+	s.Client = c
+
+	return nil
+}
+
+// GetID returns the unique store ID
+func (s *PluginStore) GetID() string {
+	ctx := context.Background()
+
+	id, err := s.Client.GetID(ctx)
+	if err != nil {
+		return fmt.Sprintf("%s.default", s.GetKind())
+	}
+	return id
+}
+
+func (s *PluginStore) GetKind() types.StoreKind {
+	return types.StoreKindPlugin
+}
+
+func (s *PluginStore) GetContextPrefix(path string) string {
+	ctx := context.Background()
+
+	prefix, err := s.Client.GetContextPrefix(ctx, path)
+	if err != nil {
+		return fmt.Sprintf("%s/%s", s.GetKind(), path)
+	}
+	return prefix
+}
+
+func (s *PluginStore) VerifyKubeconfigPaths() error {
+	ctx := context.Background()
+
+	if err := s.InitializePluginStore(); err != nil {
+		return err
+	}
+
+	return s.Client.VerifyKubeconfigPaths(ctx)
+}
+
+func (s *PluginStore) GetStoreConfig() types.KubeconfigStore {
+	return s.KubeconfigStore
+}
+
+func (s *PluginStore) GetLogger() *logrus.Entry {
+	return s.Logger
+}
+
+func (s *PluginStore) StartSearch(channel chan storetypes.SearchResult) {
+	s.Logger.Debug("Plugin: start search")
+
+	ctx := context.Background()
+
+	if err := s.InitializePluginStore(); err != nil {
+		channel <- storetypes.SearchResult{
+			KubeconfigPath: "",
+			Error:          err,
+		}
+		return
+	}
+
+	s.Client.StartSearch(ctx, channel)
+}
+
+func (s *PluginStore) GetKubeconfigForPath(path string, tags map[string]string) ([]byte, error) {
+	s.Logger.Debugf("Plugins: get kubeconfig for path %s", path)
+
+	ctx := context.Background()
+
+	if err := s.InitializePluginStore(); err != nil {
+		return nil, err
+	}
+
+	return s.Client.GetKubeconfigForPath(ctx, path, tags)
+}

pkg/store/plugins/buf.gen.yaml

@@ -0,0 +1,19 @@
+version: v2
+managed:
+  enabled: true
+  override:
+    - file_option: go_package_prefix
+      value: github.com/danielfoehrkn/kubeswitch/pkg/store/plugins
+plugins:
+  - remote: buf.build/protocolbuffers/go:v1.35.1
+    out: .
+    opt:
+      - paths=source_relative
+  - remote: buf.build/grpc/go:v1.5.1
+    out: .
+    opt:
+      - paths=source_relative
+      - require_unimplemented_servers=false
+
+inputs:
+  - directory: proto

pkg/store/plugins/buf.yaml

@@ -0,0 +1,10 @@
+# For details on buf.yaml configuration, visit https://buf.build/docs/configuration/v2/buf-yaml
+version: v2
+modules:
+  - path: proto
+lint:
+  use:
+    - STANDARD
+breaking:
+  use:
+    - FILE

pkg/store/plugins/example/README.md

@@ -0,0 +1,15 @@
+# Plugin example
+
+This is an example plugin for the store.
+
+## Usage
+
+```yaml
+kind: SwitchConfig
+version: v1alpha1
+kubeconfigStores:
+- kind: plugin
+  config:
+    cmdPath: /path/to/plugin
+    # args:
+```

pkg/store/plugins/example/go.mod

@@ -0,0 +1,28 @@
+module example.com/dumb-plugin
+
+go 1.23.3
+
+require (
+	github.com/danielfoehrkn/kubeswitch v0.0.0-00010101000000-000000000000
+	github.com/hashicorp/go-hclog v1.6.3
+	github.com/hashicorp/go-plugin v1.6.2
+)
+
+require (
+	github.com/fatih/color v1.17.0 // indirect
+	github.com/golang/protobuf v1.5.4 // indirect
+	github.com/hashicorp/yamux v0.1.1 // indirect
+	github.com/mattn/go-colorable v0.1.13 // indirect
+	github.com/mattn/go-isatty v0.0.20 // indirect
+	github.com/oklog/run v1.0.0 // indirect
+	github.com/sirupsen/logrus v1.9.3 // indirect
+	golang.org/x/net v0.30.0 // indirect
+	golang.org/x/sys v0.26.0 // indirect
+	golang.org/x/text v0.19.0 // indirect
+	google.golang.org/genproto/googleapis/rpc v0.0.0-20240903143218-8af14fe29dc1 // indirect
+	google.golang.org/grpc v1.68.0 // indirect
+	google.golang.org/protobuf v1.34.2 // indirect
+	k8s.io/apimachinery v0.31.2 // indirect
+)
+
+replace github.com/danielfoehrkn/kubeswitch => ../../../..

pkg/store/plugins/example/go.sum

@@ -0,0 +1,68 @@
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pkg/store/plugins/example/main.go

@@ -0,0 +1,83 @@
+// Copyright (c) HashiCorp, Inc.
+// SPDX-License-Identifier: MPL-2.0
+
+package main
+
+import (
+	"context"
+
+	"github.com/hashicorp/go-hclog"
+	"github.com/hashicorp/go-plugin"
+
+	"github.com/danielfoehrkn/kubeswitch/pkg/store/plugins"
+	storetypes "github.com/danielfoehrkn/kubeswitch/pkg/store/types"
+)
+
+// Store is the implementation of the store plugin
+type Store struct {
+	Logger hclog.Logger
+}
+
+// GetID returns the ID of the store
+func (s *Store) GetID(ctx context.Context) (string, error) {
+	return "example", nil
+}
+
+// GetContextPrefix returns the context prefix
+func (s *Store) GetContextPrefix(ctx context.Context, path string) (string, error) {
+	return "example", nil
+}
+
+// VerifyKubeconfigPaths verifies the kubeconfig paths
+func (s *Store) VerifyKubeconfigPaths(ctx context.Context) error {
+	return nil
+}
+
+// StartSearch starts the search
+func (s *Store) StartSearch(ctx context.Context, channel chan storetypes.SearchResult) {
+	channel <- storetypes.SearchResult{
+		KubeconfigPath: "fake",
+		Error:          nil,
+	}
+}
+
+// GetKubeconfigForPath gets the kubeconfig for the path
+func (s *Store) GetKubeconfigForPath(ctx context.Context, path string, tags map[string]string) ([]byte, error) {
+	if path == "fake" {
+		// valid fake kubeconfig
+		file := `apiVersion: v1
+kind: Config
+preferences: {}
+
+clusters:
+- name: development
+- name: test
+
+users:
+- name: developer
+- name: experimenter
+
+contexts:
+- name: dev-frontend
+- name: dev-storage
+- name: exp-test`
+		return []byte(file), nil
+	}
+
+	s.Logger.Error("invalid path")
+	return nil, nil
+}
+
+func main() {
+	logger := hclog.Default()
+	plugin.Serve(&plugin.ServeConfig{
+		HandshakeConfig: plugins.Handshake,
+		Plugins: map[string]plugin.Plugin{
+			"store": &plugins.StorePlugin{Impl: &Store{Logger: logger}},
+		},
+		Logger: logger,
+
+		// A non-nil value here enables gRPC serving for this plugin...
+		GRPCServer: plugin.DefaultGRPCServer,
+	})
+}