Discord Slack Bridge with Convex

Sync messages & threads from Discord into Slack. It will turn Discord threads into Slack threads, replying in the right thread on new messages.

My usecase is to mirror our "#support" forum in Discord into a Slack channel, so folks here don't have to periodically switch from Slack to Discord to scan, and which allows us to discuss and reference and search support threads in slack.

Installation

1. Convex backend

To run it against your own backend:

npx convex init
npx convex deploy

To save the configuration in your repo, remove "convex.json" from .gitignore. Copy the deployment URL for later (it should end with ".convex.cloud").

2. Configure Discord

Create a discord bot and authorize it, adding it to your server / guild.
Copy the token and save it in the environment variables in the dashboard with the key DISCORD_TOKEN. npx convex dashboard to get there.

3. Configure Slack

Create a slack app and install it into your workspace.
Copy the bot oauth token and save it in the convex environment variables as SLACK_TOKEN.

4. discordBot.js (on fly.io)

You can run the discordBot that connects to discord and sends changes to Convex locally to test, then deploy it to fly.io.

Locally:

pnpm i
export DISCORD_TOKEN=<discord-token>
export CONVEX_URL=<deployment-URL>
npm run clean && npm run build
node dist/discordBot.js

In Docker:

npm run clean && npm run build
docker build . -t discordbot:latest
docker run --init --env-file .env --rm discordbot:latest

Deploy the discordBot.js to fly.io:

Install flyctl, e.g. brew install flyctl
Deploy it the first time with fly launch, then fly deploy after.
Set the environment variables for it with: flyctl secrets set DISCORD_TOKEN= flyctl secrets set CONVEX_URL=

I just chose one instance in sjc, on the smallest (free) tier. I did have to enter my CC info, but it hasn't been charged.

5. Mapping Discord channels to Slack

Once messages are coming in, you'll see the channels listed in the Convex dashboard. You can edit a given channel and add slackChannelId: "C0123456ABC" for your corresponding slack channel IDs. Then, new messages will get posted to Slack, only for the Discord channels you want. Hooray!

Backfill

You can backfill a discord channel by copying the channel ID and going to the Convex dashboard, going to the "functions" section, and finding actions / discord / backfillDiscordChannel . Run it with a single parameter: { discordId: "1111111111111111111" } replacing the 1's with your discord ID.

Tip: In discord you can right-click various things and click "Copy ID"

I chose not to have this send these all to Slack, but instead just backfill into the database. Doing it multiple times won't duplicate data, it won't overwrite anything that already exists (unique on discord "id" field). If you wanted, you could have it send the slack messages, but you'd probably want to make sure you iterate over all the messages in order, so they're in order in Slack too.

For me, I just wanted the thread names and content to be in my DB for future reference, e.g. to index it for search or train GPT.

Debugging

You can look at your discordBot.js logs in the fly.io dashboard under monitoring.
You can see your convex functions in the convex dashboard under Logs
You might run into issues where your bots need extra permissions and you need to re-install them into the workspace / guild to get the right oauth token.
The discord bot doesn't catch updates to messages sent before it started up, but going forward, message updates / deletes should be sent along to slack. There's a discord-logs npm package that adds more events we could listen to in discordBot.js, maybe unhandledMessageUpdate would be useful? If you do that, send a PR please 🙏.

Search indexing

This repository also includes a cron job that ensures the appropriate discord threads are indexed into Algolia for use in search. By default, this job scans every minute for updated threads that may be eligible for indexing.

Don't worry! By default nothing is being indexed. But... what if you want to start indexing in your installation? Here's how it's done:

Add ALGOLIA_API_KEY to the deployment environment
Set a boolean field called indexForSearch to true on any channel records that are appropriate. Typically this will just be the support forum channel.
To reset the thread index scanning cursor, go into the threadSearchStatus table and update the indexedCursor number field to 0. This will ensure all threads get re-scanned for indexing eligibility

After that, any new or updated discord threads in the appopriate channel(s) will be added to the Algolia index within a minute. If you ever change the document structure, or for any other reason want to trigger a complete re-indexing of Algolia, just repeat step (3) above and set the cursor back to zero.

Extras

It has some code to handle slash commands, interactions, etc. To do this, set the URL in slack to be "https://.convex.site/slack/slash" for slash commands, or "https://.convex.site/slack/interactivity" for interactions. The slug is the part of the url in your deployment URL before convex.cloud. E.g. https://happy-iguana-123.convex.site/slack/slash . Notice the .convex.site! This is the http handlers, defined in convex/http.js.

Currently I have two shortcuts configured from slack: resolve & reply, configured as "message" shortcuts. So you can right-click a message and send a reply to Discord.

For resolve, you'll need to update the code to pass the right Tag ID. For us, we have a tag in our support channel for "Resolved".
For reply, you can add your slackUserId: "U01234ABCDE", in the users table. It won't reply as you, but it'll tag you in the reply.

Tip: you can get all your slack users & ids by running:

$ node

const token = <your slack token>;
const {WebClient} = require('@slack/web-api');
const web = new WebClient(token);
const users = await web.users.list();
users.members.map(m => `${m.real_name || m.name}: ${m.id}`)

There isn't bidirectional syncing - sending slack messages don't go to Discord. They could, but we find it's better to chat in slack between coworkers, and then go and message in Discord directly (which gets synced to slack).

Nicolapps / discord-slack-bridge