Slack

Overview

The Slack provider integrates your digital worker with Slack workspaces. It supports:

• Direct messages (DMs)
• Channel messages
• App mentions
• Interactive components (buttons, menus)
• Block Kit rich messaging
• Slash commands
• Thread replies

Prerequisites

• A Slack workspace
• Admin access to create a Slack app

Setup

1. Create a Slack configuration token pair

   Go to api.slack.com/apps and create an app configuration token pair. Copy both values:

   • Configuration access token (xoxe.xoxp-...)
   • Configuration refresh token (xoxe-1-...)

2. Configure Provider

   answers.json

   {
     "setup_answers": {
       "messaging-slack": {
         "slack_configuration_access_token": "xoxe.xoxp-xxx",
         "slack_configuration_refresh_token": "xoxe-1-xxx"
       }
     }
   }

3. Run setup

   gtc setup --answers answers.json ./my-bundle

4. Click Add to Slack

   Setup registers or updates the Slack app and exposes an Add to Slack action. Open the generated Slack authorization URL, choose the workspace, review the requested scopes, and approve the install.

   When the OAuth redirect returns to setup, Greentic persists the Slack app id, client id, client secret, and runtime OAuth answers for the tenant. If the callback was not handled automatically, run gtc setup --answers answers.json ./my-bundle again after approving the install.

5. Add the app in Slack

   Open Slack and check that the app is installed in the workspace. For channel conversations, add the app to the channel where the worker should respond. You can do this from the channel’s integration settings or by mentioning/inviting the app in the channel.

6. Start or restart the runtime

   gtc start ./my-bundle

   Startup uses the stored slack_app_id and configuration token pair to update the Slack app manifest with the current webhook URL.

7. Test the channel

   Send a direct message to the app or mention the app in the Slack channel you added it to. Channel events only arrive for channels where the app is a member and the installed scopes allow the event.

Configuration Options

Option	Required	Description
slack_configuration_access_token	Yes	Short-lived Slack configuration token used for app manifest updates
slack_configuration_refresh_token	Yes	Refresh token used to rotate the configuration access token
slack_app_id	Generated	Slack app id created or returned by setup
slack_client_id	Generated	Slack OAuth client id returned by app registration
client_secret	Generated secret	Slack OAuth client secret returned by app registration

Note

New setup flows do not require hand-entering slack_bot_token. The setup action and OAuth install flow persist the runtime credentials. If you are upgrading an older bundle, regenerate answers with gtc setup --dry-run --emit-answers answers.json ./my-bundle and re-run setup.

Caution

Slack configuration access tokens expire. Keep the matching refresh token in the setup secrets store so the provider can rotate the pair during manifest updates.

Network Access

Slack uses the Greentic runtime’s public HTTPS endpoint for all incoming callbacks. Expose the runtime through HTTPS on port 443; local development can use a tunnel that forwards the public URL to the local runtime port.

Direction	Protocol and port	Purpose
Incoming	HTTPS 443 from Slack to Greentic	Events API callbacks, interactive component payloads, slash command payloads, and OAuth redirects
Outgoing	HTTPS 443 from Greentic to slack.com and api.slack.com	OAuth exchange, Web API sends, app registration, manifest updates, and configuration token rotation

No Slack-specific TCP port needs to be opened on the Greentic host. The important inbound requirement is that Slack can reach the configured public base URL and the /v1/messaging/ingress/messaging-slack/{tenant}/{team} path over HTTPS.

Features

Text Messages

- id: reply
  type: reply
  config:
    message: "Hello! How can I help you?"

Markdown Formatting

Slack uses mrkdwn format:

- id: formatted
  type: reply
  config:
    message: |
      *Bold* _Italic_ `code`
      >Blockquote
      • Bullet point

Block Kit Messages

Use Slack’s Block Kit for rich layouts:

- id: rich_message
  type: reply
  config:
    blocks:
      - type: section
        text:
          type: mrkdwn
          text: "*Welcome!*\nHow can I assist you today?"
      - type: divider
      - type: actions
        elements:
          - type: button
            text:
              type: plain_text
              text: "Get Help"
            action_id: "help_clicked"
            value: "help"
          - type: button
            text:
              type: plain_text
              text: "View Status"
            action_id: "status_clicked"
            value: "status"

Interactive Buttons

- id: ask_action
  type: reply
  config:
    message: "What would you like to do?"
    blocks:
      - type: actions
        elements:
          - type: button
            text:
              type: plain_text
              text: "Create Ticket"
            style: primary
            action_id: "create_ticket"
          - type: button
            text:
              type: plain_text
              text: "Cancel"
            style: danger
            action_id: "cancel"

Select Menus

- id: select_option
  type: reply
  config:
    blocks:
      - type: section
        text:
          type: mrkdwn
          text: "Select a category:"
        accessory:
          type: static_select
          action_id: "category_select"
          options:
            - text:
                type: plain_text
                text: "Technical Support"
              value: "technical"
            - text:
                type: plain_text
                text: "Billing"
              value: "billing"
            - text:
                type: plain_text
                text: "General"
              value: "general"

Thread Replies

Reply in a thread:

- id: thread_reply
  type: reply
  config:
    message: "This replies in the thread"
    thread_ts: "{{original_message.thread_ts}}"

File Uploads

Slack’s file APIs change over time. Use this only when the installed messaging-slack pack exposes file support for your version; otherwise send a link or use Slack’s current external upload flow.

- id: upload_file
  type: reply
  config:
    files:
      - url: "https://example.com/report.pdf"
        filename: "report.pdf"
        title: "Monthly Report"

Ephemeral Messages

Messages only visible to one user:

- id: ephemeral
  type: reply
  config:
    message: "Only you can see this"
    ephemeral: true
    user: "{{user_id}}"

Handling Interactions

Button Clicks

flows/on_interaction.ygtc

name: handle_interaction
version: "1.0"

nodes:
  - id: route_action
    type: branch
    config:
      conditions:
        - expression: "action_id == 'help_clicked'"
          to: show_help
        - expression: "action_id == 'create_ticket'"
          to: create_ticket
      default: unknown_action

  - id: show_help
    type: reply
    config:
      message: "Here's how I can help..."

triggers:
  - type: block_action
    target: route_action

Select Menu Changes

- id: handle_select
  type: branch
  config:
    conditions:
      - expression: "selected_value == 'technical'"
        to: technical_flow
      - expression: "selected_value == 'billing'"
        to: billing_flow

Slash Commands

Note

Slash commands require additional app configuration in Slack.

1. Go to Slash Commands in your app settings
2. Create a command (e.g., /support)
3. Set Request URL to your webhook

Handle in your flow:

flows/slash_command.ygtc

name: slash_command
version: "1.0"

nodes:
  - id: handle_command
    type: reply
    config:
      message: "Support bot at your service!"
      response_type: in_channel  # or "ephemeral"

triggers:
  - type: slash_command
    command: "/support"
    target: handle_command

Channel Configuration

Single Channel

greentic.demo.yaml

tenants:
  demo:
    teams:
      support:
        channels:
          slack:
            provider: messaging-slack
            config:
              channel_id: "C1234567890"

Multiple Channels

tenants:
  demo:
    teams:
      support:
        channels:
          slack-general:
            provider: messaging-slack
            config:
              channel_id: "C1234567890"
          slack-vip:
            provider: messaging-slack
            config:
              channel_id: "C0987654321"

Troubleshooting

App Not Receiving Messages

1. Verify Event Subscriptions:

   • Check Request URL is correct
   • Ensure events are enabled
   • Verify bot is subscribed to correct events

2. Check Bot Permissions:

   • Reinstall app after adding scopes
   • Verify bot is in the channel

3. Test Webhook:

   curl https://your-domain.com/v1/messaging/ingress/messaging-slack/demo/default

“not_authed” Error

Your bot token is invalid or expired. Get a fresh token from OAuth & Permissions.

”channel_not_found” Error

• Verify channel ID is correct
• Ensure bot is added to the channel
• Check channel is not archived

Rate Limiting

Slack rate limits vary by method. Handle gracefully:

- id: reply
  type: reply
  config:
    message: "Response"
    retry_on_rate_limit: true
    max_retries: 3

Security

Caution

Verify Slack request signatures to prevent unauthorized requests.

Greentic automatically validates:

• Request timestamp
• Signature using signing secret
• Token verification

Next Steps

• Block Kit Builder - Design rich messages
• Teams Provider - Add Teams integration
• Flows Guide - Build complex workflows