Slack Triggers

Slack triggers start workflows in response to Slack events, slash commands, and interactive components like button clicks and modal submissions.

Overview

Three types of Slack triggers are supported:

Trigger Type	Use Case	Example
Event Trigger	Respond to messages, mentions, reactions	Bot @mentioned, keyword detected
Slash Command	User runs `/command`	`/invoice create`, `/approve`
Interactive	Button clicks, modal submissions	Approve button, form submission

Prerequisites

Environment Configuration

# Required for signature verification
SLACK_SIGNING_SECRET=your_signing_secret

Slack App Setup

Create a Slack App at api.slack.com/apps
Enable Event Subscriptions and point to your endpoint
Add required bot scopes
Install app to workspace

Endpoint URLs

Configure these URLs in your Slack app settings:

Feature	URL
Event Subscriptions	`https://your-domain.com/api/v1/slack/events`
Slash Commands	`https://your-domain.com/api/v1/slack/commands`
Interactivity	`https://your-domain.com/api/v1/slack/interactive`

Event Triggers

Respond to Slack Events API events like messages, mentions, and reactions.

Configuration Schema

{
  "trigger": {
    "type": "slack_event",
    "eventType": "message",
    "channelTypes": ["channel", "im"],
    "keywords": ["invoice", "billing"],
    "regex": "invoice\\s+#?\\d+",
    "userIds": ["U123456"],
    "filter": {
      "event.channel_type": { "$eq": "channel" }
    }
  }
}

Configuration Fields

Field	Type	Required	Description
`type`	string	Yes	Must be `slack_event`
`eventType`	string	Yes	Slack event type or `*` for all
`channelTypes`	array	No	Filter by channel type (`channel`, `group`, `im`, `mpim`)
`keywords`	array	No	Trigger only if message contains keyword (case-insensitive)
`regex`	string	No	Trigger only if message matches regex
`userIds`	array	No	Trigger only for specific user IDs
`filter`	object	No	Advanced filter using dot notation and operators

Supported Event Types

Event Type	Description	Key Fields
`message`	Channel or DM message	`text`, `user`, `channel`, `ts`
`app_mention`	Bot @mentioned in message	`text`, `user`, `channel`, `ts`
`reaction_added`	Emoji reaction added	`reaction`, `user`, `item.channel`, `item.ts`
`reaction_removed`	Emoji reaction removed	`reaction`, `user`, `item.channel`, `item.ts`
`channel_created`	New channel created	`channel.id`, `channel.name`, `channel.creator`
`channel_deleted`	Channel deleted	`channel`
`member_joined_channel`	User joined channel	`user`, `channel`, `inviter`
`member_left_channel`	User left channel	`user`, `channel`
`file_shared`	File uploaded	`file_id`, `user_id`, `channel_id`
`app_home_opened`	User opened Home tab	`user`, `tab`

Event Payload Structure

{
  "input": {
    "slackEvent": {
      "id": "evt_abc123",
      "source": "events_api",
      "payload": {
        "type": "event_callback",
        "team_id": "T123456",
        "api_app_id": "A123456",
        "event": {
          "type": "message",
          "user": "U123456",
          "channel": "C789012",
          "channel_type": "channel",
          "text": "Create invoice for Acme Corp",
          "ts": "1234567890.123456",
          "thread_ts": null
        },
        "event_id": "Ev123456",
        "event_time": 1234567890
      }
    }
  }
}

Example: Keyword-Based Message Trigger

{
  "name": "Invoice Request Handler",
  "trigger": {
    "type": "slack_event",
    "eventType": "message",
    "channelTypes": ["channel"],
    "keywords": ["invoice", "billing", "payment"]
  },
  "steps": [
    {
      "id": "parse-request",
      "type": "transform",
      "config": {
        "operation": "map",
        "data": {
          "user": "{{input.slackEvent.payload.event.user}}",
          "channel": "{{input.slackEvent.payload.event.channel}}",
          "text": "{{input.slackEvent.payload.event.text}}"
        }
      }
    },
    {
      "id": "notify-finance",
      "type": "slack",
      "config": {
        "action": "sendMessage",
        "channel": "#finance-requests",
        "text": "New invoice request from <@{{steps.parse-request.output.user}}>:\n> {{steps.parse-request.output.text}}"
      }
    }
  ]
}

Example: Bot Mention Trigger

{
  "name": "Bot Command Handler",
  "trigger": {
    "type": "slack_event",
    "eventType": "app_mention"
  },
  "steps": [
    {
      "id": "process-mention",
      "type": "action",
      "action": "ai.analyze",
      "config": {
        "prompt": "Parse this request and determine the intent: {{input.slackEvent.payload.event.text}}"
      }
    },
    {
      "id": "respond",
      "type": "slack",
      "config": {
        "action": "sendMessage",
        "channel": "{{input.slackEvent.payload.event.channel}}",
        "threadTs": "{{input.slackEvent.payload.event.ts}}",
        "text": "{{steps.process-mention.output.response}}"
      }
    }
  ]
}

Example: Reaction Trigger

{
  "name": "Approval via Reaction",
  "trigger": {
    "type": "slack_event",
    "eventType": "reaction_added",
    "filter": {
      "event.reaction": { "$in": ["white_check_mark", "heavy_check_mark"] }
    }
  },
  "steps": [
    {
      "id": "log-approval",
      "type": "action",
      "action": "database.insert",
      "config": {
        "table": "approvals",
        "data": {
          "approved_by": "{{input.slackEvent.payload.event.user}}",
          "message_ts": "{{input.slackEvent.payload.event.item.ts}}",
          "channel": "{{input.slackEvent.payload.event.item.channel}}"
        }
      }
    }
  ]
}

Slash Command Triggers

Respond to custom slash commands like /invoice, /approve, etc.

Configuration Schema

{
  "trigger": {
    "type": "slack_slash_command",
    "command": "/invoice"
  }
}

Configuration Fields

Field	Type	Required	Description
`type`	string	Yes	Must be `slack_slash_command`
`command`	string	Yes	The slash command (including `/`)

Command Payload Structure

{
  "input": {
    "slackEvent": {
      "id": "evt_cmd123",
      "source": "slash_command",
      "payload": {
        "token": "xxx",
        "team_id": "T123456",
        "team_domain": "myworkspace",
        "channel_id": "C789012",
        "channel_name": "general",
        "user_id": "U123456",
        "user_name": "johndoe",
        "command": "/invoice",
        "text": "create for Acme Corp $5000",
        "response_url": "https://hooks.slack.com/commands/xxx",
        "trigger_id": "123.456.xxx",
        "api_app_id": "A123456"
      }
    }
  }
}

Key Payload Fields

Field	Description
`command`	The slash command (e.g., `/invoice`)
`text`	Text after the command
`user_id`	User who ran the command
`user_name`	Username
`channel_id`	Channel where command was run
`trigger_id`	Used to open modals (expires in 3 seconds)
`response_url`	URL to send delayed responses

Example: Invoice Creation Command

{
  "name": "Create Invoice Command",
  "trigger": {
    "type": "slack_slash_command",
    "command": "/invoice"
  },
  "steps": [
    {
      "id": "parse-command",
      "type": "transform",
      "config": {
        "operation": "map",
        "data": {
          "args": "{{input.slackEvent.payload.text | split: ' '}}",
          "user": "{{input.slackEvent.payload.user_id}}",
          "channel": "{{input.slackEvent.payload.channel_id}}"
        }
      }
    },
    {
      "id": "open-modal",
      "type": "slack",
      "config": {
        "action": "openModal",
        "triggerId": "{{input.slackEvent.payload.trigger_id}}",
        "view": {
          "type": "modal",
          "callback_id": "create_invoice_modal",
          "title": { "type": "plain_text", "text": "Create Invoice" },
          "submit": { "type": "plain_text", "text": "Create" },
          "blocks": [
            {
              "type": "input",
              "block_id": "customer",
              "element": {
                "type": "plain_text_input",
                "action_id": "customer_input",
                "initial_value": "{{steps.parse-command.output.args[0]}}"
              },
              "label": { "type": "plain_text", "text": "Customer" }
            },
            {
              "type": "input",
              "block_id": "amount",
              "element": {
                "type": "plain_text_input",
                "action_id": "amount_input"
              },
              "label": { "type": "plain_text", "text": "Amount" }
            }
          ]
        }
      }
    }
  ]
}

Example: Help Command

{
  "name": "Help Command",
  "trigger": {
    "type": "slack_slash_command",
    "command": "/workflow-help"
  },
  "steps": [
    {
      "id": "send-help",
      "type": "action",
      "action": "http.post",
      "config": {
        "url": "{{input.slackEvent.payload.response_url}}",
        "body": {
          "response_type": "ephemeral",
          "blocks": [
            {
              "type": "section",
              "text": {
                "type": "mrkdwn",
                "text": "*Available Commands:*\n• `/invoice create` - Create a new invoice\n• `/invoice list` - List recent invoices\n• `/approve` - View pending approvals"
              }
            }
          ]
        }
      }
    }
  ]
}

Interactive Triggers

Respond to button clicks, menu selections, modal submissions, and shortcuts.

Configuration Schema

{
  "trigger": {
    "type": "slack_interactive",
    "interactionType": "block_actions",
    "actionId": "approve_button",
    "callbackId": "approval_modal",
    "filter": {
      "actions[0].value": { "$exists": true }
    }
  }
}

Configuration Fields

Field	Type	Required	Description
`type`	string	Yes	Must be `slack_interactive`
`interactionType`	string	Yes	Interaction type or `*` for all
`actionId`	string	No	Filter by action_id (for `block_actions`)
`callbackId`	string	No	Filter by callback_id (for modals/shortcuts)
`filter`	object	No	Advanced filter

Interaction Types

Type	Description	When Triggered
`block_actions`	Button click, menu selection	User clicks button or selects option
`view_submission`	Modal form submitted	User submits modal
`view_closed`	Modal closed	User closes modal without submitting
`shortcut`	Global shortcut	User runs global shortcut
`message_action`	Message shortcut	User runs message shortcut

Interactive Payload Structure

Block Actions (Button Click):

{
  "input": {
    "slackEvent": {
      "id": "evt_int123",
      "source": "interactive",
      "payload": {
        "type": "block_actions",
        "team": { "id": "T123456", "domain": "myworkspace" },
        "user": { "id": "U123456", "name": "johndoe" },
        "channel": { "id": "C789012", "name": "general" },
        "message": { "ts": "1234567890.123456" },
        "trigger_id": "123.456.xxx",
        "response_url": "https://hooks.slack.com/actions/xxx",
        "actions": [
          {
            "action_id": "approve_invoice",
            "block_id": "approval_block",
            "type": "button",
            "value": "inv_12345"
          }
        ]
      }
    }
  }
}

View Submission (Modal):

{
  "input": {
    "slackEvent": {
      "id": "evt_modal123",
      "source": "interactive",
      "payload": {
        "type": "view_submission",
        "team": { "id": "T123456" },
        "user": { "id": "U123456", "name": "johndoe" },
        "trigger_id": "123.456.xxx",
        "view": {
          "id": "V123456",
          "callback_id": "create_invoice_modal",
          "private_metadata": "{\"channel\":\"C789012\"}",
          "state": {
            "values": {
              "customer": {
                "customer_input": { "value": "Acme Corp" }
              },
              "amount": {
                "amount_input": { "value": "5000" }
              }
            }
          }
        }
      }
    }
  }
}

Example: Button Click Handler

{
  "name": "Handle Approval Button",
  "trigger": {
    "type": "slack_interactive",
    "interactionType": "block_actions",
    "actionId": "approve_invoice"
  },
  "steps": [
    {
      "id": "get-invoice",
      "type": "action",
      "action": "quickbooks.getInvoice",
      "config": {
        "invoiceId": "{{input.slackEvent.payload.actions[0].value}}"
      }
    },
    {
      "id": "approve",
      "type": "action",
      "action": "quickbooks.updateInvoice",
      "config": {
        "invoiceId": "{{input.slackEvent.payload.actions[0].value}}",
        "status": "approved"
      }
    },
    {
      "id": "notify",
      "type": "action",
      "action": "http.post",
      "config": {
        "url": "{{input.slackEvent.payload.response_url}}",
        "body": {
          "replace_original": true,
          "text": ":white_check_mark: Invoice approved by <@{{input.slackEvent.payload.user.id}}>"
        }
      }
    }
  ]
}

{
  "name": "Process Invoice Modal",
  "trigger": {
    "type": "slack_interactive",
    "interactionType": "view_submission",
    "callbackId": "create_invoice_modal"
  },
  "steps": [
    {
      "id": "extract-values",
      "type": "transform",
      "config": {
        "operation": "map",
        "data": {
          "customer": "{{input.slackEvent.payload.view.state.values.customer.customer_input.value}}",
          "amount": "{{input.slackEvent.payload.view.state.values.amount.amount_input.value}}",
          "metadata": "{{input.slackEvent.payload.view.private_metadata | parseJson}}"
        }
      }
    },
    {
      "id": "create-invoice",
      "type": "action",
      "action": "quickbooks.createInvoice",
      "config": {
        "customerName": "{{steps.extract-values.output.customer}}",
        "amount": "{{steps.extract-values.output.amount}}"
      }
    },
    {
      "id": "confirm",
      "type": "slack",
      "config": {
        "action": "sendMessage",
        "channel": "{{steps.extract-values.output.metadata.channel}}",
        "text": ":white_check_mark: Invoice created for {{steps.extract-values.output.customer}} - ${{steps.extract-values.output.amount}}"
      }
    }
  ]
}

Built-in Approval Handling

The platform includes built-in support for human-in-the-loop approvals via Slack. When a workflow step uses the approval type with Slack notifications, approval buttons are automatically handled.

Automatic Approval Button Handling

Buttons with action IDs matching approval_approve_<token> or approval_reject_<token> are automatically processed:

The approval decision is recorded
The waiting workflow is resumed
The Slack message is updated with the decision

No custom trigger configuration is needed for approval workflows.

Important Behavior

3-Second Acknowledgment Rule

Slack requires responses within 3 seconds. All triggers:

Acknowledge immediately with a brief response
Process the event asynchronously
Use response_url for delayed responses

// Immediate acknowledgment (automatic)
{ "ok": true }
 
// Delayed response via response_url
{
  "replace_original": true,
  "text": "Processing complete!"
}

URL Verification

When setting up Event Subscriptions, Slack sends a verification challenge. This is handled automatically:

// Slack sends:
{ "type": "url_verification", "challenge": "abc123" }
 
// Endpoint responds:
{ "challenge": "abc123" }

Retry Deduplication

Slack retries failed requests with headers:

X-Slack-Retry-Num: Retry attempt number
X-Slack-Retry-Reason: Reason for retry

Retries are automatically deduplicated using Redis with a 1-hour TTL.

Signature Verification

All requests are verified using HMAC-SHA256:

Compute: v0:timestamp:raw_body
Sign with SLACK_SIGNING_SECRET
Compare with X-Slack-Signature header
Reject if timestamp is >5 minutes old (replay attack prevention)

Filter Operators

Use these operators in the filter configuration:

Operator	Description	Example
`$eq`	Equal to	`{ "event.type": { "$eq": "message" } }`
`$ne`	Not equal to	`{ "event.channel_type": { "$ne": "im" } }`
`$in`	In array	`{ "event.reaction": { "$in": ["thumbsup", "heart"] } }`
`$exists`	Field exists	`{ "event.thread_ts": { "$exists": true } }`

Access nested fields with dot notation: event.item.channel

Troubleshooting

Common Issues

Issue	Cause	Solution
Signature verification failed	Wrong secret or clock skew	Verify `SLACK_SIGNING_SECRET`, check server time
Events not received	Wrong URL or app not installed	Check Event Subscriptions URL, reinstall app
Modal won't open	Expired trigger_id	Open modal within 3 seconds of receiving event
Duplicate events	Retries not deduplicated	Check Redis connection
Missing scopes	Insufficient permissions	Add required scopes in app settings

Required Scopes by Feature

Feature	Required Scopes
Receive messages	`channels:history`, `groups:history`, `im:history`, `mpim:history`
Receive mentions	`app_mentions:read`
Slash commands	(configured per command)
Interactive	(automatic with Interactivity URL)
Post messages	`chat:write`
Open modals	(automatic with bot token)

Debug Logging

Events are logged at these points:

Signature verification result
Event deduplication check
Matching workflow discovery
Workflow trigger success/failure

Check logs for Slack event processing failed or Failed to trigger workflow from Slack event.

Slack Block - Send messages and interact with Slack
Webhook Triggers - Other webhook-based triggers
Approval Steps - Human-in-the-loop approvals

Slack Triggers

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