MM-57018: support reattaching plugins (mattermost#26421)

* ProfileImageBytes for EnsureBotOptions

* leverage plugintest.NewAPI

* fix linting

* add UpdateUserRoles to plugin api

* MM-57018: support reattaching plugins

Expose a local-only API for reattaching plugins: instead of the server starting and managing the process itself, allow the plugin to be launched externally (eg within a unit test) and reattach to an existing server instance to provide the unit test with a fully functional RPC API, sidestepping the need for mocking the plugin API in most cases.

In the future, this may become the basis for running plugins in a sidecar container.

Fixes: https://mattermost.atlassian.net/browse/MM-57018

* drop unused supervisor.pid

* factor out checkMinServerVersion

* factor out startPluginServer

* restore missing setPluginState on successful reattach

* avoid passing around a stale registeredPlugin

* inline initializePluginImplementation

* have IsValid return an error

* explicitly close rpcClient

In the case of reattached plugins, the Unix socket won't necessarily disappear leaving the muxBrokers blocked indefinitely. And `Kill()` doesn't do anything if there's no process being managed.

* explicitly detachPlugin

* emphasize gRPC not being supported

---------

Co-authored-by: Mattermost Build <[email protected]>

server/channels/api4/plugin_local.go

@@ -3,6 +3,13 @@
 
 package api4
 
+import (
+	"encoding/json"
+	"net/http"
+
+	"github.com/mattermost/mattermost/server/public/model"
+)
+
 func (api *API) InitPluginLocal() {
 	api.BaseRoutes.Plugins.Handle("", api.APILocal(uploadPlugin, handlerParamFileAPI)).Methods("POST")
 	api.BaseRoutes.Plugins.Handle("", api.APILocal(getPlugins)).Methods("GET")
@@ -12,4 +19,44 @@ func (api *API) InitPluginLocal() {
 	api.BaseRoutes.Plugin.Handle("/disable", api.APILocal(disablePlugin)).Methods("POST")
 	api.BaseRoutes.Plugins.Handle("/marketplace", api.APILocal(installMarketplacePlugin)).Methods("POST")
 	api.BaseRoutes.Plugins.Handle("/marketplace", api.APILocal(getMarketplacePlugins)).Methods("GET")
+	api.BaseRoutes.Plugins.Handle("/reattach", api.APILocal(reattachPlugin)).Methods("POST")
+	api.BaseRoutes.Plugin.Handle("/detach", api.APILocal(detachPlugin)).Methods("POST")
+}
+
+// reattachPlugin allows the server to bind to an existing plugin instance launched elsewhere.
+//
+// This API is only exposed over a local socket.
+func reattachPlugin(c *Context, w http.ResponseWriter, r *http.Request) {
+	var pluginReattachRequest model.PluginReattachRequest
+	if err := json.NewDecoder(r.Body).Decode(&pluginReattachRequest); err != nil {
+		c.Err = model.NewAppError("reattachPlugin", "api4.plugin.reattachPlugin.invalid_request", nil, err.Error(), http.StatusBadRequest)
+		return
+	}
+
+	if err := pluginReattachRequest.IsValid(); err != nil {
+		c.Err = err
+		return
+	}
+
+	err := c.App.ReattachPlugin(pluginReattachRequest.Manifest, pluginReattachRequest.PluginReattachConfig)
+	if err != nil {
+		c.Err = err
+		return
+	}
+}
+
+// detachPlugin detaches a previously reattached plugin.
+//
+// This API is only exposed over a local socket.
+func detachPlugin(c *Context, w http.ResponseWriter, r *http.Request) {
+	c.RequirePluginId()
+	if c.Err != nil {
+		return
+	}
+
+	err := c.App.DetachPlugin(c.Params.PluginId)
+	if err != nil {
+		c.Err = err
+		return
+	}
 }

server/channels/app/plugin_reattach.go

@@ -0,0 +1,50 @@
+// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
+// See LICENSE.txt for license information.
+package app
+
+import (
+	"net/http"
+
+	"github.com/mattermost/mattermost/server/public/model"
+)
+
+// ReattachPlugin allows the server to bind to an existing plugin instance launched elsewhere.
+func (a *App) ReattachPlugin(manifest *model.Manifest, pluginReattachConfig *model.PluginReattachConfig) *model.AppError {
+	return a.ch.ReattachPlugin(manifest, pluginReattachConfig)
+}
+
+// ReattachPlugin allows the server to bind to an existing plugin instance launched elsewhere.
+func (ch *Channels) ReattachPlugin(manifest *model.Manifest, pluginReattachConfig *model.PluginReattachConfig) *model.AppError {
+	pluginsEnvironment := ch.GetPluginsEnvironment()
+	if pluginsEnvironment == nil {
+		return model.NewAppError("ReattachPlugin", "app.plugin.disabled.app_error", nil, "", http.StatusNotImplemented)
+	}
+
+	ch.DetachPlugin(manifest.Id)
+
+	// Reattach to the plugin
+	if err := pluginsEnvironment.Reattach(manifest, pluginReattachConfig); err != nil {
+		return model.NewAppError("ReattachPlugin", "app.plugin.reattach.app_error", nil, "", http.StatusInternalServerError).Wrap(err)
+	}
+
+	return nil
+}
+
+// DetachPlugin allows the server to bind to an existing plugin instance launched elsewhere.
+func (a *App) DetachPlugin(pluginId string) *model.AppError {
+	return a.ch.DetachPlugin(pluginId)
+}
+
+// DetachPlugin allows the server to bind to an existing plugin instance launched elsewhere.
+func (ch *Channels) DetachPlugin(pluginID string) *model.AppError {
+	pluginsEnvironment := ch.GetPluginsEnvironment()
+	if pluginsEnvironment == nil {
+		return model.NewAppError("DetachPlugin", "app.plugin.disabled.app_error", nil, "", http.StatusNotImplemented)
+	}
+
+	// Deactivate and remove any existing plugin, if present.
+	pluginsEnvironment.Deactivate(pluginID)
+	pluginsEnvironment.RemovePlugin(pluginID)
+
+	return nil
+}

server/i18n/en.json

@@ -4614,6 +4614,10 @@
     "id": "api.websocket_handler.server_busy.app_error",
     "translation": "Server is busy, non-critical services are temporarily unavailable."
   },
+  {
+    "id": "api4.plugin.reattachPlugin.invalid_request",
+    "translation": "Failed to parse request"
+  },
   {
     "id": "app.acknowledgement.delete.app_error",
     "translation": "Unable to delete acknowledgement."
@@ -6290,6 +6294,10 @@
     "id": "app.plugin.not_installed.app_error",
     "translation": "Plugin is not installed."
   },
+  {
+    "id": "app.plugin.reattach.app_error",
+    "translation": "Failed to reattach plugin"
+  },
   {
     "id": "app.plugin.remove.app_error",
     "translation": "Unable to delete plugin."
@@ -10142,6 +10150,14 @@
     "id": "plugin_api.send_mail.missing_to",
     "translation": "Missing TO address."
   },
+  {
+    "id": "plugin_reattach_request.is_valid.manifest.app_error",
+    "translation": "Missing manifest"
+  },
+  {
+    "id": "plugin_reattach_request.is_valid.plugin_reattach_config.app_error",
+    "translation": "Missing plugin reattach config"
+  },
   {
     "id": "searchengine.bleve.disabled.error",
     "translation": "Error purging Bleve indexes: engine is disabled"

server/public/model/client4.go

@@ -7352,6 +7352,36 @@ func (c *Client4) InstallMarketplacePlugin(ctx context.Context, request *Install
 	return &m, BuildResponse(r), nil
 }
 
+// ReattachPlugin asks the server to reattach to a plugin launched by another process.
+//
+// Only available in local mode, and currently only used for testing.
+func (c *Client4) ReattachPlugin(ctx context.Context, request *PluginReattachRequest) (*Response, error) {
+	buf, err := json.Marshal(request)
+	if err != nil {
+		return nil, NewAppError("ReattachPlugin", "api.marshal_error", nil, "", http.StatusInternalServerError).Wrap(err)
+	}
+	r, err := c.DoAPIPost(ctx, c.pluginsRoute()+"/reattach", string(buf))
+	if err != nil {
+		return BuildResponse(r), err
+	}
+	defer closeBody(r)
+
+	return BuildResponse(r), nil
+}
+
+// DetachPlugin detaches a previously reattached plugin.
+//
+// Only available in local mode, and currently only used for testing.
+func (c *Client4) DetachPlugin(ctx context.Context, pluginID string) (*Response, error) {
+	r, err := c.DoAPIPost(ctx, c.pluginRoute(pluginID)+"/detach", "")
+	if err != nil {
+		return BuildResponse(r), err
+	}
+	defer closeBody(r)
+
+	return BuildResponse(r), nil
+}
+
 // GetPlugins will return a list of plugin manifests for currently active plugins.
 func (c *Client4) GetPlugins(ctx context.Context) (*PluginsResponse, *Response, error) {
 	r, err := c.DoAPIGet(ctx, c.pluginsRoute(), "")

server/public/model/plugin_reattach.go

@@ -0,0 +1,59 @@
+package model
+
+import (
+	"net"
+	"net/http"
+
+	"github.com/hashicorp/go-plugin"
+)
+
+// PluginReattachConfig is a serializable version of go-plugin's ReattachConfig.
+type PluginReattachConfig struct {
+	Protocol        string
+	ProtocolVersion int
+	Addr            net.UnixAddr
+	Pid             int
+	Test            bool
+}
+
+func NewPluginReattachConfig(pluginReattachmentConfig *plugin.ReattachConfig) *PluginReattachConfig {
+	return &PluginReattachConfig{
+		Protocol:        string(pluginReattachmentConfig.Protocol),
+		ProtocolVersion: pluginReattachmentConfig.ProtocolVersion,
+		Addr: net.UnixAddr{
+			Name: pluginReattachmentConfig.Addr.String(),
+			Net:  pluginReattachmentConfig.Addr.Network(),
+		},
+		Pid:  pluginReattachmentConfig.Pid,
+		Test: pluginReattachmentConfig.Test,
+	}
+}
+
+func (prc *PluginReattachConfig) ToHashicorpPluginReattachmentConfig() *plugin.ReattachConfig {
+	addr := prc.Addr
+
+	return &plugin.ReattachConfig{
+		Protocol:        plugin.Protocol(prc.Protocol),
+		ProtocolVersion: prc.ProtocolVersion,
+		Addr:            &addr,
+		Pid:             prc.Pid,
+		ReattachFunc:    nil,
+		Test:            prc.Test,
+	}
+}
+
+type PluginReattachRequest struct {
+	Manifest             *Manifest
+	PluginReattachConfig *PluginReattachConfig
+}
+
+func (prr *PluginReattachRequest) IsValid() *AppError {
+	if prr.Manifest == nil {
+		return NewAppError("PluginReattachRequest.IsValid", "plugin_reattach_request.is_valid.manifest.app_error", nil, "", http.StatusBadRequest)
+	}
+	if prr.PluginReattachConfig == nil {
+		return NewAppError("PluginReattachRequest.IsValid", "plugin_reattach_request.is_valid.plugin_reattach_config.app_error", nil, "", http.StatusBadRequest)
+	}
+
+	return nil
+}