Backend Plugins: Plugin configuration using Grafana config (#23451)

Enables adding a section `plugin.<plugin id>` and key/value to
Grafana configuration file which will be converted and sent
as environment variables to the backend plugin.
Also sends some additional environment variables, Grafana
version (GF_VERSION), Grafana edition (GF_EDITION) and 
enterprise license path (GF_ENTERPRISE_LICENSE_PATH).

Co-authored-by: Arve Knudsen <arve.knudsen@gmail.com>

Fixes #21515,

pkg/plugins/backendplugin/client.go

@@ -30,9 +30,12 @@ var handshake = goplugin.HandshakeConfig{
 	MagicCookieValue: grpcplugin.MagicCookieValue,
 }
 
-func newClientConfig(executablePath string, logger log.Logger, versionedPlugins map[int]goplugin.PluginSet) *goplugin.ClientConfig {
+func newClientConfig(executablePath string, env []string, logger log.Logger, versionedPlugins map[int]goplugin.PluginSet) *goplugin.ClientConfig {
+	cmd := exec.Command(executablePath)
+	cmd.Env = env
+
 	return &goplugin.ClientConfig{
-		Cmd:              exec.Command(executablePath),
+		Cmd:              cmd,
 		HandshakeConfig:  handshake,
 		VersionedPlugins: versionedPlugins,
 		Logger:           logWrapper{Logger: logger},

pkg/plugins/backendplugin/manager.go

@@ -3,11 +3,13 @@ package backendplugin
 import (
 	"context"
 	"errors"
+	"fmt"
 	"io"
 	"sync"
 	"time"
 
 	"github.com/grafana/grafana/pkg/models"
+	"github.com/grafana/grafana/pkg/setting"
 	"github.com/grafana/grafana/pkg/util/errutil"
 	"github.com/grafana/grafana/pkg/util/proxyutil"
 
@@ -49,14 +51,18 @@ type Manager interface {
 }
 
 type manager struct {
-	pluginsMu sync.RWMutex
-	plugins   map[string]*BackendPlugin
-	logger    log.Logger
+	Cfg            *setting.Cfg     `inject:""`
+	License        models.Licensing `inject:""`
+	pluginsMu      sync.RWMutex
+	plugins        map[string]*BackendPlugin
+	logger         log.Logger
+	pluginSettings map[string]pluginSettings
 }
 
 func (m *manager) Init() error {
 	m.plugins = make(map[string]*BackendPlugin)
 	m.logger = log.New("plugins.backend")
+	m.pluginSettings = extractPluginSettings(m.Cfg)
 
 	return nil
 }
@@ -78,13 +84,29 @@ func (m *manager) Register(descriptor PluginDescriptor) error {
 		return errors.New("Backend plugin already registered")
 	}
 
+	pluginSettings := pluginSettings{}
+	if ps, exists := m.pluginSettings[descriptor.pluginID]; exists {
+		pluginSettings = ps
+	}
+
+	hostEnv := []string{
+		fmt.Sprintf("GF_VERSION=%s", setting.BuildVersion),
+		fmt.Sprintf("GF_EDITION=%s", m.License.Edition()),
+	}
+
+	if m.License.HasLicense() {
+		hostEnv = append(hostEnv, fmt.Sprintf("GF_ENTERPRISE_LICENSE_PATH=%s", m.Cfg.EnterpriseLicensePath))
+	}
+
+	env := pluginSettings.ToEnv("GF_PLUGIN", hostEnv)
+
 	pluginLogger := m.logger.New("pluginId", descriptor.pluginID)
 	plugin := &BackendPlugin{
 		id:             descriptor.pluginID,
 		executablePath: descriptor.executablePath,
 		managed:        descriptor.managed,
 		clientFactory: func() *plugin.Client {
-			return plugin.NewClient(newClientConfig(descriptor.executablePath, pluginLogger, descriptor.versionedPlugins))
+			return plugin.NewClient(newClientConfig(descriptor.executablePath, env, pluginLogger, descriptor.versionedPlugins))
 		},
 		startFns: descriptor.startFns,
 		logger:   pluginLogger,

pkg/plugins/backendplugin/plugin_settings.go

@@ -0,0 +1,39 @@
+package backendplugin
+
+import (
+	"fmt"
+	"strings"
+
+	"github.com/grafana/grafana/pkg/setting"
+)
+
+type pluginSettings map[string]string
+
+func (ps pluginSettings) ToEnv(prefix string, hostEnv []string) []string {
+	env := []string{}
+	for k, v := range ps {
+		env = append(env, fmt.Sprintf("%s_%s=%s", prefix, strings.ToUpper(k), v))
+	}
+
+	env = append(env, hostEnv...)
+
+	return env
+}
+
+func extractPluginSettings(cfg *setting.Cfg) map[string]pluginSettings {
+	psMap := map[string]pluginSettings{}
+	for pluginID, settings := range cfg.PluginSettings {
+		ps := pluginSettings{}
+		for k, v := range settings {
+			if k == "path" || strings.ToLower(k) == "id" {
+				continue
+			}
+
+			ps[k] = v
+		}
+
+		psMap[pluginID] = ps
+	}
+
+	return psMap
+}

pkg/plugins/backendplugin/plugin_settings_test.go

@@ -0,0 +1,46 @@
+package backendplugin
+
+import (
+	"sort"
+	"testing"
+
+	"github.com/grafana/grafana/pkg/setting"
+	"github.com/stretchr/testify/require"
+)
+
+func TestPluginSettings(t *testing.T) {
+	t.Run("Should only extract from sections beginning with 'plugin.' in config", func(t *testing.T) {
+		cfg := &setting.Cfg{
+			PluginSettings: setting.PluginSettings{
+				"plugin": map[string]string{
+					"key1": "value1",
+					"key2": "value2",
+				},
+			},
+		}
+
+		ps := extractPluginSettings(cfg)
+		require.Len(t, ps, 1)
+		require.Len(t, ps["plugin"], 2)
+
+		t.Run("Should skip path setting", func(t *testing.T) {
+			cfg.PluginSettings["plugin"]["path"] = "value"
+			ps := extractPluginSettings(cfg)
+			require.Len(t, ps["plugin"], 2)
+		})
+
+		t.Run("Should skip id setting", func(t *testing.T) {
+			cfg.PluginSettings["plugin"]["id"] = "value"
+			ps := extractPluginSettings(cfg)
+			require.Len(t, ps["plugin"], 2)
+		})
+
+		t.Run("Should return expected environment variables from plugin settings ", func(t *testing.T) {
+			ps := extractPluginSettings(cfg)
+			env := ps["plugin"].ToEnv("GF_PLUGIN", []string{"GF_VERSION=6.7.0"})
+			sort.Strings(env)
+			require.Len(t, env, 3)
+			require.EqualValues(t, []string{"GF_PLUGIN_KEY1=value1", "GF_PLUGIN_KEY2=value2", "GF_VERSION=6.7.0"}, env)
+		})
+	})
+}