# Setting up Appservice Slack bridging (optional)

**Notes**:
- Bridging to [Slack](https://slack.com) can also happen via the [mx-puppet-slack](configuring-playbook-bridge-mx-puppet-slack.md) and [mautrix-slack](configuring-playbook-bridge-mautrix-slack.md) bridges supported by the playbook.
- Currently (as of November, 2024) this component is not available for new installation unless you have already created a classic Slack application (which the bridge makes use of in order to enable bridging between Slack and Matrix), because the creation of classic Slack applications has been discontinued since June 4 2024. The author of the bridge claims [here](https://github.com/matrix-org/matrix-appservice-slack/issues/789#issuecomment-2172947787) that he plans to support the modern Slack application and until then "the best (and only) option for new installations is to use the webhook bridging".

The playbook can install and configure [matrix-appservice-slack](https://github.com/matrix-org/matrix-appservice-slack) for you.

See the project's [documentation](https://github.com/matrix-org/matrix-appservice-slack/blob/master/README.md) to learn what it does and why it might be useful to you.

## Setup Instructions:

loosely based on [this](https://github.com/matrix-org/matrix-appservice-slack#Setup)

1. Create a new Matrix room to act as the administration control room. Note its internal room ID. This can be done in Element Web by sending a message, opening the options for that message and choosing "view source". The room ID will be displayed near the top.

2. Enable the bridge by adding the following configuration to your `inventory/host_vars/matrix.example.com/vars.yml` file:

    ```yaml
    matrix_appservice_slack_enabled: true
    matrix_appservice_slack_control_room_id: "Your Matrix admin room ID"
    ```

3. Enable puppeting (optional, but recommended)

    ```yaml
    matrix_appservice_slack_puppeting_enabled: true
    matrix_appservice_slack_puppeting_slackapp_client_id: "Your Classic Slack App Client ID"
    matrix_appservice_slack_puppeting_slackapp_client_secret: "Your Classic Slack App Client Secret"
    ```

4. Enable Team Sync (optional)

    ```yaml
    matrix_appservice_slack_team_sync_enabled: true
    ```

    See https://matrix-appservice-slack.readthedocs.io/en/latest/team_sync/

5. If you've already installed Matrix services using the playbook before, you'll need to re-run it (`--tags=setup-all,start`). If not, proceed with [configuring other playbook services](configuring-playbook.md) and then with [Installing](installing.md). Get back to this guide once ready.

6. Invite the bridge bot user into the admin room:

    ```
    /invite @slackbot:example.com
    ```

    Note that the bot's domain is your server's domain **without the `matrix.` prefix.**

7. Create a Classic Slack App [here](https://api.slack.com/apps?new_classic_app=1).

    Name the app "matrixbot" (or anything else you'll remember).

    Select the team/workspace this app will belong to.

    Click on bot users and add a new bot user. We will use this account to bridge the the rooms.

8. Click on Event Subscriptions and enable them and use the request url `https://matrix.example.com/appservice-slack`. Then add the following events and save:

     Bot User Events:

    - team_domain_change
    - message.channels
    - message.groups (if you want to bridge private channels)
    - reaction_added
    - reaction_removed

9. Click on OAuth & Permissions and add the following scopes:

    - chat:write:bot
    - users:read
    - reactions:write

    If you want to bridge files, also add the following:

    - files:write:user

    **Note**: In order to make Slack files visible to Matrix users, this bridge will make Slack files visible to anyone with the url (including files in private channels). This is different than the current behavior in Slack, which only allows authenticated access to media posted in private channels. See MSC701 for details.

10. Click on Install App and Install App to Workspace. Note the access tokens shown. You will need the Bot User OAuth Access Token and if you want to bridge files, the OAuth Access Token whenever you link a room.

11. If Team Sync is not enabled, for each channel you would like to bridge, perform the following steps:

    * Create a Matrix room in the usual manner for your client. Take a note of its Matrix room ID - it will look something like !qporfwt:example.com.

    * Invite the bot user to both the Slack and Matrix channels you would like to bridge using `/invite @matrixbot` for Slack and `/invite @slackbot:example.com` for Matrix.

    * Determine the "channel ID" that Slack uses to identify the channel. You can see it when you open a given Slack channel in a browser. The URL reads like this: `https://app.slack.com/client/XXX/<the channel ID>/details/`.

    * Issue a link command in the administration control room with these collected values as arguments:

        with file bridging:

        ```
        link --channel_id CHANNELID --room !qporfwt:example.com --slack_bot_token xoxb-xxxxxxxxxx-xxxxxxxxxxxxxxxxxxxx --slack_user_token xoxp-xxxxxxxx-xxxxxxxxx-xxxxxxxx-xxxxxxxx
        ```

        without file bridging:

        ```
        link --channel_id CHANNELID --room !qporfwt:example.com --slack_bot_token xoxb-xxxxxxxxxx-xxxxxxxxxxxxxxxxxxxx
        ```

        These arguments can be shortened to single-letter forms:

        ```
        link -I CHANNELID -R !qporfwt:example.com -t xoxb-xxxxxxxxxx-xxxxxxxxxxxxxxxxxxxx
        ```

        Other configuration options are available via the `matrix_appservice_slack_configuration_extension_yaml` variable.

12. Unlinking

    Channels can be unlinked again like this:

    ```
    unlink --room !qporfwt:example.com
    ```

    Unlinking doesn't only disconnect the bridge, but also makes the slackbot leave the bridged Matrix room. So in case you want to re-link later, don't forget to re-invite the slackbot into this room again.

## Troubleshooting

* As always, check the logs: `journalctl -fu matrix-appservice-slack`

* Linking: "Room is now pending-name"

  This typically means that you haven't used the correct Slack channel ID. Unlink the room and recheck 'Determine the "channel ID"' from above.

* Messages work from M to S, but not the other way around

  Check you logs, if they say something like

  `WARN SlackEventHandler Ignoring message from unrecognised Slack channel ID : %s (%s) <the channel ID> <some other ID>`

  then unlink your room, reinvite the bot and re-link it again. This may particularly hit you, if you tried to unsuccessfully link your room multiple times without unlinking it after each failed attempt.