fix: Change slackapp to using scheduleMessage (#4490)

### What
This PR changes the slack-app addon to use slack-api's scheduleMessage
instead of postMessage.

### Why
When using postMessage we had to find the channel id in order to be able
to post the message to the channel. scheduleMessage allows using the
channel name instead of the id, which saves the entire struggle of
finding the channel name. It did mean that we had to move to defining
blocks of content instead of the easier formatting we did with
postMessage.

### Message look

![image](https://github.com/Unleash/unleash/assets/177402/a9079c4d-07c0-4846-ad0c-67130e77fb3b)

package.json

@@ -104,7 +104,7 @@
     ]
   },
   "dependencies": {
-    "@slack/web-api": "^6.8.1",
+    "@slack/web-api": "^6.9.0",
     "@unleash/express-openapi": "^0.3.0",
     "ajv": "^8.11.0",
     "ajv-formats": "^2.1.1",

src/lib/addons/slack-app.ts

@@ -1,6 +1,5 @@
 import {
     WebClient,
-    ConversationsListResponse,
     ErrorCode,
     WebClientEvent,
     CodedError,
@@ -13,7 +12,7 @@ import Addon from './addon';
 
 import slackAppDefinition from './slack-app-definition';
 import { IAddonConfig } from '../types/model';
-
+const SCHEDULE_MESSAGE_DELAY_IN_SECONDS = 10;
 import {
     FeatureEventFormatter,
     FeatureEventFormatterMd,
@@ -21,8 +20,6 @@ import {
 } from './feature-event-formatter-md';
 import { IEvent } from '../types/events';
 
-const CACHE_SECONDS = 30;
-
 interface ISlackAppAddonParameters {
     accessToken: string;
     defaultChannels: string;
@@ -35,17 +32,12 @@ export default class SlackAppAddon extends Addon {
 
     private slackClient?: WebClient;
 
-    private slackChannels?: ConversationsListResponse['channels'];
-
-    private slackChannelsCacheTimeout?: NodeJS.Timeout;
-
     constructor(args: IAddonConfig) {
         super(slackAppDefinition, args);
         this.msgFormatter = new FeatureEventFormatterMd(
             args.unleashUrl,
             LinkStyle.SLACK,
         );
-        this.startCacheInvalidation();
     }
 
     async handleEvent(
@@ -83,95 +75,42 @@ export default class SlackAppAddon extends Addon {
                 this.accessToken = accessToken;
             }
 
-            if (!this.slackChannels) {
-                const slackConversationsList =
-                    await this.slackClient.conversations.list({
-                        types: 'public_channel,private_channel',
-                        exclude_archived: true,
-                        limit: 200,
-                    });
-                this.slackChannels = slackConversationsList.channels || [];
-                let nextCursor =
-                    slackConversationsList.response_metadata?.next_cursor;
-                while (nextCursor !== undefined && nextCursor !== '') {
-                    this.logger.debug('Fetching next page of channels');
-                    const moreChannels =
-                        await this.slackClient.conversations.list({
-                            cursor: nextCursor,
-                            types: 'public_channel,private_channel',
-                            exclude_archived: true,
-                            limit: 200,
-                        });
-                    const channels = moreChannels.channels;
-                    if (channels === undefined) {
-                        this.logger.debug(
-                            'Channels list was empty, breaking pagination',
-                        );
-                        nextCursor = undefined;
-                        break;
-                    }
-                    nextCursor = moreChannels.response_metadata?.next_cursor;
-                    this.logger.debug(
-                        `This page had ${channels.length} channels`,
-                    );
-
-                    channels.forEach((channel) =>
-                        this.slackChannels?.push(channel),
-                    );
-                }
-
-                this.logger.debug(
-                    `Fetched ${
-                        this.slackChannels.length
-                    } available Slack channels: ${this.slackChannels.map(
-                        ({ name }) => name,
-                    )}`,
-                );
-            }
-
-            const currentSlackChannels = [...this.slackChannels];
-            if (!currentSlackChannels.length) {
-                this.logger.warn('No available Slack channels found.');
-                return;
-            }
-
             const text = this.msgFormatter.format(event);
             const url = this.msgFormatter.featureLink(event);
-
+            const requests = eventChannels.map((name) => {
-            const slackChannelsToPostTo = currentSlackChannels.filter(
+                const now = Math.floor(new Date().getTime() / 1000);
-                ({ id, name }) => id && name && eventChannels.includes(name),
+                const postAt = now + SCHEDULE_MESSAGE_DELAY_IN_SECONDS;
-            );
+                return this.slackClient!.chat.scheduleMessage({
-
+                    channel: name,
-            if (!slackChannelsToPostTo.length) {
-                this.logger.info('No eligible Slack channel found.');
-                return;
-            }
-            this.logger.debug(
-                `Posting event to ${slackChannelsToPostTo.map(
-                    ({ name }) => name,
-                )}.`,
-            );
-
-            const requests = slackChannelsToPostTo.map(({ id }) =>
-                this.slackClient!.chat.postMessage({
-                    channel: id!,
                     text,
-                    attachments: [
+                    blocks: [
                         {
-                            actions: [
+                            type: 'section',
+                            text: {
+                                type: 'mrkdwn',
+                                text,
+                            },
+                        },
+                        {
+                            type: 'actions',
+                            block_id: url,
+                            elements: [
                                 {
-                                    name: 'featureToggle',
-                                    text: 'Open in Unleash',
                                     type: 'button',
+                                    url,
+                                    text: {
+                                        type: 'plain_text',
+                                        text: 'Open in Unleash',
+                                    },
                                     value: 'featureToggle',
                                     style: 'primary',
-                                    url,
                                 },
                             ],
                         },
                     ],
-                }),
+                    post_at: postAt,
-            );
+                });
+            });
 
             const results = await Promise.allSettled(requests);
 
@@ -208,12 +147,6 @@ export default class SlackAppAddon extends Addon {
         return [];
     }
 
-    startCacheInvalidation(): void {
-        this.slackChannelsCacheTimeout = setInterval(() => {
-            this.slackChannels = undefined;
-        }, CACHE_SECONDS * 1000);
-    }
-
     logError(event: IEvent, error: Error | CodedError): void {
         if (!('code' in error)) {
             this.logger.warn(`Error handling event ${event.type}.`, error);
@@ -248,13 +181,6 @@ export default class SlackAppAddon extends Addon {
             this.logger.warn(`Error handling event ${event.type}.`, error);
         }
     }
-
-    destroy(): void {
-        if (this.slackChannelsCacheTimeout) {
-            clearInterval(this.slackChannelsCacheTimeout);
-            this.slackChannelsCacheTimeout = undefined;
-        }
-    }
 }
 
 module.exports = SlackAppAddon;

yarn.lock

@@ -1068,24 +1068,24 @@
   dependencies:
     "@types/node" ">=12.0.0"
 
-"@slack/types@^2.0.0":
+"@slack/types@^2.8.0":
   version "2.8.0"
   resolved "https://registry.yarnpkg.com/@slack/types/-/types-2.8.0.tgz#11ea10872262a7e6f86f54e5bcd4f91e3a41fe91"
   integrity sha512-ghdfZSF0b4NC9ckBA8QnQgC9DJw2ZceDq0BIjjRSv6XAZBXJdWgxIsYz0TYnWSiqsKZGH2ZXbj9jYABZdH3OSQ==
 
-"@slack/web-api@^6.8.1":
+"@slack/web-api@^6.9.0":
-  version "6.8.1"
+  version "6.9.0"
-  resolved "https://registry.yarnpkg.com/@slack/web-api/-/web-api-6.8.1.tgz#c6c1e7405c884c4d9048f8b1d3901bd138d00610"
+  resolved "https://registry.yarnpkg.com/@slack/web-api/-/web-api-6.9.0.tgz#d829dcfef490dbce8e338912706b6f39dcde3ad2"
-  integrity sha512-eMPk2S99S613gcu7odSw/LV+Qxr8A+RXvBD0GYW510wJuTERiTjP5TgCsH8X09+lxSumbDE88wvWbuFuvGa74g==
+  integrity sha512-RME5/F+jvQmZHkoP+ogrDbixq1Ms1mBmylzuWq4sf3f7GCpMPWoiZ+WqWk+sism3vrlveKWIgO9R4Qg9fiRyoQ==
   dependencies:
     "@slack/logger" "^3.0.0"
-    "@slack/types" "^2.0.0"
+    "@slack/types" "^2.8.0"
     "@types/is-stream" "^1.1.0"
     "@types/node" ">=12.0.0"
     axios "^0.27.2"
     eventemitter3 "^3.1.0"
     form-data "^2.5.0"
-    is-electron "2.2.0"
+    is-electron "2.2.2"
     is-stream "^1.1.0"
     p-queue "^6.6.1"
     p-retry "^4.0.0"
@@ -4359,10 +4359,10 @@ is-date-object@^1.0.1:
   dependencies:
     has-tostringtag "^1.0.0"
 
-is-electron@2.2.0:
+is-electron@2.2.2:
-  version "2.2.0"
+  version "2.2.2"
-  resolved "https://registry.yarnpkg.com/is-electron/-/is-electron-2.2.0.tgz#8943084f09e8b731b3a7a0298a7b5d56f6b7eef0"
+  resolved "https://registry.yarnpkg.com/is-electron/-/is-electron-2.2.2.tgz#3778902a2044d76de98036f5dc58089ac4d80bb9"
-  integrity sha512-SpMppC2XR3YdxSzczXReBjqs2zGscWQpBIKqwXYBFic0ERaxNVgwLCHwOLZeESfdJQjX0RDvrJ1lBXX2ij+G1Q==
+  integrity sha512-FO/Rhvz5tuw4MCWkpMzHFKWD2LsfHzIb7i6MdPYZ/KW7AlxawyLkqdy+jPZP1WubqEADE3O4FUENlJHDfQASRg==
 
 is-extendable@^0.1.1:
   version "0.1.1"