MM-10702 Moving plugins to use hashicorp go-plugin. (#8978)

* Moving plugins to use hashicorp go-plugin.

* Tweaks from feedback.

1 files changed, 260 insertions, 0 deletions

diff --git a/plugin/environment.go b/plugin/environment.go
new file mode 100644
index 000000000..de67225d2
--- /dev/null
+++ b/plugin/environment.go
@@ -0,0 +1,260 @@
+// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
+// See LICENSE.txt for license information.
+
+package plugin
+
+import (
+	"fmt"
+	"io/ioutil"
+	"path/filepath"
+	"sync"
+
+	"github.com/mattermost/mattermost-server/mlog"
+	"github.com/mattermost/mattermost-server/model"
+	"github.com/pkg/errors"
+)
+
+type APIImplCreatorFunc func(*model.Manifest) API
+type SupervisorCreatorFunc func(*model.BundleInfo, *mlog.Logger, API) (*Supervisor, error)
+
+// Hooks will be the hooks API for the plugin
+// Return value should be true if we should continue calling more plugins
+type MultliPluginHookRunnerFunc func(hooks Hooks) bool
+
+type ActivePlugin struct {
+	BundleInfo *model.BundleInfo
+	State      int
+	Supervisor *Supervisor
+}
+
+type Environment struct {
+	activePlugins   map[string]ActivePlugin
+	mutex           sync.RWMutex
+	logger          *mlog.Logger
+	newAPIImpl      APIImplCreatorFunc
+	pluginDir       string
+	webappPluginDir string
+}
+
+func NewEnvironment(newAPIImpl APIImplCreatorFunc, pluginDir string, webappPluginDir string, logger *mlog.Logger) (*Environment, error) {
+	return &Environment{
+		activePlugins:   make(map[string]ActivePlugin),
+		logger:          logger,
+		newAPIImpl:      newAPIImpl,
+		pluginDir:       pluginDir,
+		webappPluginDir: webappPluginDir,
+	}, nil
+}
+
+// Performs a full scan of the given path.
+//
+// This function will return info for all subdirectories that appear to be plugins (i.e. all
+// subdirectories containing plugin manifest files, regardless of whether they could actually be
+// parsed).
+//
+// Plugins are found non-recursively and paths beginning with a dot are always ignored.
+func ScanSearchPath(path string) ([]*model.BundleInfo, error) {
+	files, err := ioutil.ReadDir(path)
+	if err != nil {
+		return nil, err
+	}
+	var ret []*model.BundleInfo
+	for _, file := range files {
+		if !file.IsDir() || file.Name()[0] == '.' {
+			continue
+		}
+		if info := model.BundleInfoForPath(filepath.Join(path, file.Name())); info.ManifestPath != "" {
+			ret = append(ret, info)
+		}
+	}
+	return ret, nil
+}
+
+// Returns a list of all plugins within the environment.
+func (env *Environment) Available() ([]*model.BundleInfo, error) {
+	return ScanSearchPath(env.pluginDir)
+}
+
+// Returns a list of all currently active plugins within the environment.
+func (env *Environment) Active() []*model.BundleInfo {
+	env.mutex.RLock()
+	defer env.mutex.RUnlock()
+
+	activePlugins := []*model.BundleInfo{}
+	for _, p := range env.activePlugins {
+		activePlugins = append(activePlugins, p.BundleInfo)
+	}
+
+	return activePlugins
+}
+
+func (env *Environment) IsActive(id string) bool {
+	_, ok := env.activePlugins[id]
+	return ok
+}
+
+// Returns a list of plugin statuses reprensenting the state of every plugin
+func (env *Environment) Statuses() (model.PluginStatuses, error) {
+	env.mutex.RLock()
+	defer env.mutex.RUnlock()
+
+	plugins, err := env.Available()
+	if err != nil {
+		return nil, errors.Wrap(err, "unable to get plugin statuses")
+	}
+
+	pluginStatuses := make(model.PluginStatuses, 0, len(plugins))
+	for _, plugin := range plugins {
+		// For now we don't handle bad manifests, we should
+		if plugin.Manifest == nil {
+			continue
+		}
+
+		pluginState := model.PluginStateNotRunning
+		if plugin, ok := env.activePlugins[plugin.Manifest.Id]; ok {
+			pluginState = plugin.State
+		}
+
+		status := &model.PluginStatus{
+			PluginId:    plugin.Manifest.Id,
+			PluginPath:  filepath.Dir(plugin.ManifestPath),
+			State:       pluginState,
+			Name:        plugin.Manifest.Name,
+			Description: plugin.Manifest.Description,
+			Version:     plugin.Manifest.Version,
+		}
+
+		pluginStatuses = append(pluginStatuses, status)
+	}
+
+	return pluginStatuses, nil
+}
+
+func (env *Environment) Activate(id string) (reterr error) {
+	env.mutex.Lock()
+	defer env.mutex.Unlock()
+
+	// Check if we are already active
+	if _, ok := env.activePlugins[id]; ok {
+		return nil
+	}
+
+	plugins, err := env.Available()
+	if err != nil {
+		return err
+	}
+	var pluginInfo *model.BundleInfo
+	for _, p := range plugins {
+		if p.Manifest != nil && p.Manifest.Id == id {
+			if pluginInfo != nil {
+				return fmt.Errorf("multiple plugins found: %v", id)
+			}
+			pluginInfo = p
+		}
+	}
+	if pluginInfo == nil {
+		return fmt.Errorf("plugin not found: %v", id)
+	}
+
+	activePlugin := ActivePlugin{BundleInfo: pluginInfo}
+	defer func() {
+		if reterr == nil {
+			activePlugin.State = model.PluginStateRunning
+		} else {
+			activePlugin.State = model.PluginStateFailedToStart
+		}
+		env.activePlugins[pluginInfo.Manifest.Id] = activePlugin
+	}()
+
+	if pluginInfo.Manifest.Webapp != nil {
+		bundlePath := filepath.Clean(pluginInfo.Manifest.Webapp.BundlePath)
+		if bundlePath == "" || bundlePath[0] == '.' {
+			return fmt.Errorf("invalid webapp bundle path")
+		}
+		bundlePath = filepath.Join(env.pluginDir, id, bundlePath)
+
+		webappBundle, err := ioutil.ReadFile(bundlePath)
+		if err != nil {
+			return errors.Wrapf(err, "unable to read webapp bundle: %v", id)
+		}
+
+		err = ioutil.WriteFile(fmt.Sprintf("%s/%s_bundle.js", env.webappPluginDir, id), webappBundle, 0644)
+		if err != nil {
+			return errors.Wrapf(err, "unable to write webapp bundle: %v", id)
+		}
+	}
+
+	if pluginInfo.Manifest.Backend != nil {
+		supervisor, err := NewSupervisor(pluginInfo, env.logger, env.newAPIImpl(pluginInfo.Manifest))
+		if err != nil {
+			return errors.Wrapf(err, "unable to start plugin: %v", id)
+		}
+		activePlugin.Supervisor = supervisor
+	}
+
+	return nil
+}
+
+// Deactivates the plugin with the given id.
+func (env *Environment) Deactivate(id string) {
+	env.mutex.Lock()
+	defer env.mutex.Unlock()
+
+	if activePlugin, ok := env.activePlugins[id]; !ok {
+		return
+	} else {
+		delete(env.activePlugins, id)
+		if activePlugin.Supervisor != nil {
+			if err := activePlugin.Supervisor.Hooks().OnDeactivate(); err != nil {
+				env.logger.Error("Plugin OnDeactivate() error", mlog.String("plugin_id", activePlugin.BundleInfo.Manifest.Id), mlog.Err(err))
+			}
+			activePlugin.Supervisor.Shutdown()
+		}
+	}
+}
+
+// Deactivates all plugins and gracefully shuts down the environment.
+func (env *Environment) Shutdown() {
+	env.mutex.Lock()
+	defer env.mutex.Unlock()
+
+	for _, activePlugin := range env.activePlugins {
+		if activePlugin.Supervisor != nil {
+			if err := activePlugin.Supervisor.Hooks().OnDeactivate(); err != nil {
+				env.logger.Error("Plugin OnDeactivate() error", mlog.String("plugin_id", activePlugin.BundleInfo.Manifest.Id), mlog.Err(err))
+			}
+			activePlugin.Supervisor.Shutdown()
+		}
+	}
+	env.activePlugins = make(map[string]ActivePlugin)
+	return
+}
+
+// Returns the hooks API for the plugin ID specified
+// You should probably use RunMultiPluginHook instead.
+func (env *Environment) HooksForPlugin(id string) (Hooks, error) {
+	env.mutex.RLock()
+	defer env.mutex.RUnlock()
+
+	if plug, ok := env.activePlugins[id]; ok && plug.Supervisor != nil {
+		return plug.Supervisor.Hooks(), nil
+	}
+
+	return nil, fmt.Errorf("plugin not found: %v", id)
+}
+
+// Calls hookRunnerFunc with the hooks for each active plugin that implments the given HookId
+// If hookRunnerFunc returns false, then iteration will not continue.
+func (env *Environment) RunMultiPluginHook(hookRunnerFunc MultliPluginHookRunnerFunc, mustImplement int) {
+	env.mutex.RLock()
+	defer env.mutex.RUnlock()
+
+	for _, activePlugin := range env.activePlugins {
+		if activePlugin.Supervisor == nil || !activePlugin.Supervisor.Implements(mustImplement) {
+			continue
+		}
+		if !hookRunnerFunc(activePlugin.Supervisor.Hooks()) {
+			break
+		}
+	}
+}