Slack triggers

A Slack trigger starts a run when something happens in a Slack workspace your company has connected: a message is posted, someone runs a slash command, or someone clicks a button. There are three trigger types:

Connect Slack first. Loopfour finds the company for an incoming request by the Slack workspace ID (team_id) on your Slack connection. A request from a workspace with no connection starts nothing.

Slack events

Configuration

{
  "trigger": {
    "type": "slack_event",
    "eventType": "message",
    "channelTypes": ["channel"],
    "keywords": ["invoice", "refund"]
  }
}

eventType is one of: message, app_mention, reaction_added, reaction_removed, channel_created, channel_archive, channel_unarchive, channel_rename, member_joined_channel, member_left_channel, file_shared, file_created, app_home_opened, link_shared, or * for any of them.

In Studio, add a Slack block and switch it to trigger mode. The block shows Event, Channel Types, User IDs, Keywords (for message and app mention events) and Filter (JSON). Studio does not offer * or regex; set those through the API.

How filters apply

• channelTypes and userIds only filter events that carry a channel type or a user. An event without one passes.
• keywords and regex only filter events that have text. An event with no text passes.
• An invalid regex is skipped, not treated as a failure.
• Every condition you set must pass.

Events that are skipped

• Messages from bots, including Loopfour's own Slack app. This stops a workflow that posts to Slack from triggering itself.
• For message and * triggers, housekeeping message subtypes: message_deleted, message_changed, channel_join, channel_leave, channel_topic, channel_purpose, channel_name, channel_archive, channel_unarchive, pinned_item and unpinned_item. File uploads (file_share) and thread replies sent to the channel (thread_broadcast) still start runs.

Slash commands

{
  "trigger": {
    "type": "slack_slash_command",
    "command": "/invoice",
    "usageHint": "[customer] [amount]"
  }
}

Slack only sends a command that is set up in the Slack app. command matches a command that arrives; it does not create one in Slack.

The person who runs the command sees a private reply, Processing /invoice..., straight away. The run starts after that. Whatever they typed after the command is in text.

The slash command trigger has no Studio block. Set it in the definition through the API.

Interactions

{
  "trigger": {
    "type": "slack_interactive",
    "interactionType": "block_actions",
    "actionId": "start_month_end_close"
  }
}

Clicks on the buttons of a Loopfour approval step are handled as approval decisions. They do not start runs.

The interactive trigger has no Studio block. Set it in the definition through the API.

What the run receives

Every Slack trigger puts the request into input.slackEvent. The run is recorded with triggerType: "webhook".

What sits in payload depends on the source:

For example, a step reads the message text as {{input.slackEvent.payload.event.text}} and the slash command arguments as {{input.slackEvent.payload.text}}. See Variable references.

Filters

filter is a JSON object. Each key is a dot path into the Slack request body, and each value is either a plain value (must be equal) or an operator object with $eq, $ne, $in or $exists. All keys must pass.

{ "event.channel": { "$eq": "C01234567" } }

For slack_event, paths start at the Events API body, so the message fields are under event.. For slack_interactive, paths start at the interaction payload.

Endpoints

Loopfour's Slack app sends requests to these routes. You do not call them yourself.

Each request must carry a valid Slack signature (x-slack-signature, version v0, HMAC-SHA256 over v0:<timestamp>:<raw body>) and an x-slack-request-timestamp within five minutes. Otherwise it gets 401. The routes use the webhook rate limit of 10,000 requests per minute per IP address.

Loopfour answers Slack straight away and matches workflows afterwards, so Slack's three-second limit is met even when many workflows listen.

Repeated deliveries

Slack resends a request it thinks failed. Loopfour remembers each Events API event_id, and the trigger_id of each slash command or interaction for one hour and ignores a repeat in that time. A repeated slash command gets the private reply Command already processed.

Test without Slack

Start the workflow by hand with a sample request as input:

curl -X POST "https://workflow.loopfour.ai/api/v1/workflows/$WORKFLOW_ID/run" \
  -H "x-api-key: $LOOPFOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "input": {
      "slackEvent": {
        "id": "test-1",
        "source": "events_api",
        "payload": {
          "team_id": "T01234567",
          "event": { "type": "message", "user": "U01234567", "text": "Invoice for Acme, 4200 USD", "channel": "C01234567", "channel_type": "channel" }
        }
      }
    }
  }'

See API trigger for the response.