unpack prepacked plugins on plugins initialization (#9149)

* unpack prepackaged plugins on plugins initialization

* leverage utils.FindDir

app/plugin.go

@@ -6,11 +6,13 @@ package app
 import (
 	"net/http"
 	"os"
+	"path/filepath"
 	"strings"
 
 	"github.com/mattermost/mattermost-server/mlog"
 	"github.com/mattermost/mattermost-server/model"
 	"github.com/mattermost/mattermost-server/plugin"
+	"github.com/mattermost/mattermost-server/utils"
 )
 
 func (a *App) SyncPluginsActiveState() {
@@ -101,6 +103,25 @@ func (a *App) InitPlugins(pluginDir, webappPluginDir string) {
 		a.Plugins = env
 	}
 
+	prepackagedPluginsDir, found := utils.FindDir("prepackaged_plugins")
+	if found {
+		if err := filepath.Walk(prepackagedPluginsDir, func(walkPath string, info os.FileInfo, err error) error {
+			if !strings.HasSuffix(walkPath, ".tar.gz") {
+				return nil
+			}
+
+			if fileReader, err := os.Open(walkPath); err != nil {
+				mlog.Error("Failed to open prepackaged plugin", mlog.Err(err), mlog.String("path", walkPath))
+			} else if _, err := a.InstallPlugin(fileReader, true); err != nil {
+				mlog.Error("Failed to unpack prepackaged plugin", mlog.Err(err), mlog.String("path", walkPath))
+			}
+
+			return nil
+		}); err != nil {
+			mlog.Error("Failed to complete unpacking prepackaged plugins", mlog.Err(err))
+		}
+	}
+
 	// Sync plugin active state when config changes. Also notify plugins.
 	a.RemoveConfigListener(a.PluginConfigListenerId)
 	a.PluginConfigListenerId = a.AddConfigListener(func(*model.Config, *model.Config) {

app/plugin_install.go

@@ -17,11 +17,11 @@ import (
 )
 
 // InstallPlugin unpacks and installs a plugin but does not enable or activate it.
-func (a *App) InstallPlugin(pluginFile io.Reader) (*model.Manifest, *model.AppError) {
-	return a.installPlugin(pluginFile)
+func (a *App) InstallPlugin(pluginFile io.Reader, replace bool) (*model.Manifest, *model.AppError) {
+	return a.installPlugin(pluginFile, replace)
 }
 
-func (a *App) installPlugin(pluginFile io.Reader) (*model.Manifest, *model.AppError) {
+func (a *App) installPlugin(pluginFile io.Reader, replace bool) (*model.Manifest, *model.AppError) {
 	if a.Plugins == nil || !*a.Config().PluginSettings.Enable {
 		return nil, model.NewAppError("installPlugin", "app.plugin.disabled.app_error", nil, "", http.StatusNotImplemented)
 	}
@@ -63,7 +63,13 @@ func (a *App) installPlugin(pluginFile io.Reader) (*model.Manifest, *model.AppEr
 	// Check that there is no plugin with the same ID
 	for _, bundle := range bundles {
 		if bundle.Manifest != nil && bundle.Manifest.Id == manifest.Id {
-			return nil, model.NewAppError("installPlugin", "app.plugin.install_id.app_error", nil, "", http.StatusBadRequest)
+			if !replace {
+				return nil, model.NewAppError("installPlugin", "app.plugin.install_id.app_error", nil, "", http.StatusBadRequest)
+			}
+
+			if err := a.RemovePlugin(manifest.Id); err != nil {
+				return nil, model.NewAppError("installPlugin", "app.plugin.install_id_failed_remove.app_error", nil, "", http.StatusBadRequest)
+			}
 		}
 	}