add experimental plugin system

sdk/plugin/plugin.go

@@ -0,0 +1,166 @@
+// Package plugin provides support for the SFTPGo plugin system
+package plugin
+
+import (
+	"fmt"
+	"sync"
+
+	"github.com/hashicorp/go-hclog"
+
+	"github.com/drakkan/sftpgo/v2/logger"
+	"github.com/drakkan/sftpgo/v2/sdk/plugin/notifier"
+)
+
+const (
+	logSender = "plugins"
+)
+
+var (
+	// Handler defines the plugins manager
+	Handler         Manager
+	pluginsLogLevel = hclog.Debug
+)
+
+// Renderer defines the interface for generic objects rendering
+type Renderer interface {
+	RenderAsJSON(reload bool) ([]byte, error)
+}
+
+// Config defines a plugin configuration
+type Config struct {
+	// Plugin type
+	Type string `json:"type" mapstructure:"type"`
+	// NotifierOptions defines additional options for notifiers plugins
+	NotifierOptions NotifierConfig `json:"notifier_options" mapstructure:"notifier_options"`
+	// Path to the plugin executable
+	Cmd string `json:"cmd" mapstructure:"cmd"`
+	// Args to pass to the plugin executable
+	Args []string `json:"args" mapstructure:"args"`
+	// SHA256 checksum for the plugin executable.
+	// If not empty it will be used to verify the integrity of the executable
+	SHA256Sum string `json:"sha256sum" mapstructure:"sha256sum"`
+	// If enabled the client and the server automatically negotiate mTLS for
+	// transport authentication. This ensures that only the original client will
+	// be allowed to connect to the server, and all other connections will be
+	// rejected. The client will also refuse to connect to any server that isn't
+	// the original instance started by the client.
+	AutoMTLS bool `json:"auto_mtls" mapstructure:"auto_mtls"`
+}
+
+// Manager handles enabled plugins
+type Manager struct {
+	// List of configured plugins
+	Configs   []Config `json:"plugins" mapstructure:"plugins"`
+	mu        sync.RWMutex
+	notifiers []*notifierPlugin
+}
+
+// Initialize initializes the configured plugins
+func Initialize(configs []Config, logVerbose bool) error {
+	Handler = Manager{
+		Configs: configs,
+	}
+
+	if logVerbose {
+		pluginsLogLevel = hclog.Debug
+	} else {
+		pluginsLogLevel = hclog.Info
+	}
+
+	for _, config := range configs {
+		switch config.Type {
+		case notifier.PluginName:
+			plugin, err := newNotifierPlugin(config)
+			if err != nil {
+				return err
+			}
+			Handler.notifiers = append(Handler.notifiers, plugin)
+		default:
+			return fmt.Errorf("unsupported plugin type: %v", config.Type)
+		}
+	}
+	return nil
+}
+
+// NotifyFsEvent sends the fs event notifications using any defined notifier plugins
+func (m *Manager) NotifyFsEvent(action, username, fsPath, fsTargetPath, sshCmd, protocol string, fileSize int64, err error) {
+	m.mu.RLock()
+
+	var crashedIdxs []int
+	for idx, n := range m.notifiers {
+		if n.exited() {
+			crashedIdxs = append(crashedIdxs, idx)
+		} else {
+			n.notifyFsAction(action, username, fsPath, fsTargetPath, sshCmd, protocol, fileSize, err)
+		}
+	}
+
+	m.mu.RUnlock()
+
+	if len(crashedIdxs) > 0 {
+		m.restartCrashedNotifiers(crashedIdxs)
+
+		m.mu.RLock()
+		defer m.mu.RUnlock()
+
+		for idx := range crashedIdxs {
+			if !m.notifiers[idx].exited() {
+				m.notifiers[idx].notifyFsAction(action, username, fsPath, fsTargetPath, sshCmd, protocol, fileSize, err)
+			}
+		}
+	}
+}
+
+// NotifyUserEvent sends the user event notifications using any defined notifier plugins
+func (m *Manager) NotifyUserEvent(action string, user Renderer) {
+	m.mu.RLock()
+
+	var crashedIdxs []int
+	for idx, n := range m.notifiers {
+		if n.exited() {
+			crashedIdxs = append(crashedIdxs, idx)
+		} else {
+			n.notifyUserAction(action, user)
+		}
+	}
+
+	m.mu.RUnlock()
+
+	if len(crashedIdxs) > 0 {
+		m.restartCrashedNotifiers(crashedIdxs)
+
+		m.mu.RLock()
+		defer m.mu.RUnlock()
+
+		for idx := range crashedIdxs {
+			if !m.notifiers[idx].exited() {
+				m.notifiers[idx].notifyUserAction(action, user)
+			}
+		}
+	}
+}
+
+func (m *Manager) restartCrashedNotifiers(crashedIdxs []int) {
+	for _, idx := range crashedIdxs {
+		m.mu.Lock()
+		defer m.mu.Unlock()
+
+		if m.notifiers[idx].exited() {
+			logger.Info(logSender, "", "try to restart crashed plugin %v", m.Configs[idx].Cmd)
+			plugin, err := newNotifierPlugin(m.Configs[idx])
+			if err == nil {
+				m.notifiers[idx] = plugin
+			} else {
+				logger.Warn(logSender, "", "plugin %v crashed and restart failed: %v", m.Configs[idx].Cmd, err)
+			}
+		}
+	}
+}
+
+// Cleanup releases all the active plugins
+func (m *Manager) Cleanup() {
+	for _, n := range m.notifiers {
+		logger.Debug(logSender, "", "cleanup plugin %v", n.config.Cmd)
+		n.cleanup()
+	}
+}