POC Slack App bridging

config/config.sample.yaml

@@ -70,6 +70,13 @@ rtm:
   #
   log_level: "silent"
 
+# Use a Slack App for bridging. This is the recommended method.
+#
+# slack_app:
+#   appToken: 'xapp-foo-bar-baz'
+#   botToken: 'xoxb-baz-bar-foo'
+#   signingSecret: 'feed1337beefcafe'
+
 # Port for incoming Slack requests from webhooks and event API messages
 # Optional if using RTM API, required otherwise.
 #

package.json

@@ -35,6 +35,7 @@
   "homepage": "https://github.com/matrix-org/matrix-appservice-slack#readme",
   "dependencies": {
     "@alloc/quick-lru": "^5.2.0",
+    "@slack/bolt": "^3.18.0",
     "@slack/logger": "^3.0.0",
     "@slack/rtm-api": "^6.0.0",
     "@slack/web-api": "^6.7.2",

src/BridgedRoom.ts

@@ -485,7 +485,6 @@ export class BridgedRoom {
         }
         const body: ISlackChatMessagePayload = {
             ...matrixToSlackResult,
-            as_user: false,
             username: (await user.getDisplaynameForRoom(message.room_id)) || matrixToSlackResult.username,
         };
         const text = body.text;
@@ -524,7 +523,7 @@ export class BridgedRoom {
             // Webhooks don't give us any ID, so we can't store this.
             return true;
         }
-        if (puppetedClient) {
+        if (puppetedClient && this.main.teamIsUsingRtm(this.SlackTeamId!)) {
             body.as_user = true;
             delete body.username;
         }

src/IConfig.ts

@@ -88,6 +88,12 @@ export interface IConfig {
         log_level?: string;
     };
 
+    slack_app?: {
+        appToken: string,
+        botToken: string,
+        signingSecret: string,
+    };
+
     slack_hook_port?: number;
     slack_client_opts?: WebClientOptions;
     slack_proxy?: string;

src/Main.ts

@@ -46,6 +46,7 @@ import { UserAdminRoom } from "./rooms/UserAdminRoom";
 import { TeamSyncer } from "./TeamSyncer";
 import { SlackGhostStore } from "./SlackGhostStore";
 import { AllowDenyList, DenyReason } from "./AllowDenyList";
+import { SlackAppHandler } from "./SlackAppHandler";
 
 const log = new Logger("Main");
 
@@ -146,6 +147,7 @@ export class Main {
     public readonly allowDenyList: AllowDenyList;
 
     public slackRtm?: SlackRTMHandler;
+    public slackAppHandler?: SlackAppHandler;
     private slackHookHandler?: SlackHookHandler;
 
     private provisioner: Provisioner;
@@ -175,9 +177,12 @@ export class Main {
 
         this.matrixUsersById = new QuickLRU({ maxSize: config.caching.matrixUserCache });
 
-        if ((!config.rtm || !config.rtm.enable) && (!config.slack_hook_port || !config.inbound_uri_prefix)) {
-            throw Error("Neither rtm.enable nor slack_hook_port|inbound_uri_prefix is defined in the config." +
-            "The bridge must define a listener in order to run");
+        if (
+            (!config.rtm || !config.rtm.enable)
+            && (!config.slack_hook_port || !config.inbound_uri_prefix)
+            && !config.slack_app
+        ) {
+            throw Error("No RTM, no webhooks and no Slack App configured. The bridge must define a listener in order to run");
         }
 
         if ((!config.rtm?.enable || !config.oauth2) && config.puppeting?.enabled) {
@@ -1264,6 +1269,10 @@ export class Main {
             await this.bridgeBlocker?.checkLimits(this.bridge.opts.controller.userActivityTracker.countActiveUsers().allUsers);
         }
 
+        if (this.config.slack_app) {
+            this.slackAppHandler = await SlackAppHandler.create(this, this.config.slack_app);
+        }
+
         log.info("Bridge initialised");
         this.ready = true;
         return port;

src/SlackAppHandler.ts

@@ -0,0 +1,73 @@
+import { App, KnownEventFromType, ReactionAddedEvent, ReactionRemovedEvent, SlackEvent } from "@slack/bolt";
+import { Main, METRIC_RECEIVED_MESSAGE } from "./Main";
+import { SlackEventHandler } from "./SlackEventHandler";
+import { Logger } from "matrix-appservice-bridge";
+import { ISlackEvent } from "./BaseSlackHandler";
+
+const log = new Logger("SlackAppHandler");
+
+interface Config {
+    appToken: string,
+    signingSecret: string,
+    botToken: string,
+}
+
+export class SlackAppHandler extends SlackEventHandler {
+    private constructor(
+        main: Main,
+        private app: App,
+        private teamId: string
+    ) {
+        super(main);
+        this.app.message(async ({ message }) => this.handleSlackAppEvent(message));
+        this.app.event(new RegExp('^reaction'), ({ event }) => this.handleSlackAppEvent(event));
+    }
+
+    public static async create(main: Main, config: Config) {
+        const app = new App({
+            appToken: config.appToken,
+            token: config.botToken,
+            signingSecret: config.signingSecret,
+            socketMode: true,
+        });
+        await app.start();
+        const teamId = await main.clientFactory.upsertTeamByToken(config.botToken);
+        log.info(`Slack App listening for events for team ${teamId}`);
+        return new SlackAppHandler(main, app, teamId);
+    }
+
+    private async handleSlackAppEvent(ev: SlackEvent) {
+        try {
+            switch (ev.type) {
+                case 'message': return this.onMessage(ev);
+                case 'reaction_added':
+                case 'reaction_removed':
+                    return this.onReaction(ev);
+                default:
+                    log.warn(`Ignoring event of type ${ev.type}`);
+            }
+        } catch (err) {
+            log.error(`Failed to handle Slack App event ${JSON.stringify(ev, undefined, 2)}: ${err}`);
+        }
+    }
+
+    private async onMessage(msg: KnownEventFromType<'message'>) {
+        log.debug("Received a message:", msg);
+
+        this.main.incCounter(METRIC_RECEIVED_MESSAGE, { side: "remote" });
+
+        switch (msg.subtype) {
+            case undefined: // regular message
+                return this.handleEvent({
+                    ...msg,
+                    user_id: msg.user,
+                }, this.teamId);
+            default:
+                log.warn(`Unhandled message subtype ${msg.subtype}`);
+        }
+    }
+
+    async onReaction(ev: ReactionAddedEvent|ReactionRemovedEvent): Promise<void> {
+        return this.handleEvent(ev as unknown as ISlackEvent, this.teamId);
+    }
+}