Slack Trigger

input.slack Input v0.1.0

Starts the workflow when a Slack event arrives (Events API). Answers the url_verification challenge and normalizes each event to a flat { text, user, channel, ts, eventType, team, … } shape.

The Slack Trigger step on the Studio canvas — The **Slack Trigger** step as it appears on the Studio canvas — input pins on the left, output ports on the right.

Finding it in the library

Search the builder's node library for Slack Trigger (it lives under Input). A single click opens the in-editor docs panel shown here — description, ports, and every property, without leaving the canvas. Double-click (or drag) to add it to the workflow.

Slack Trigger in the node library, with the in-editor docs panel open — The library entry and the in-editor docs panel for **Slack Trigger** — the same reference this page is generated from.

Wired up in the builder

Slack Trigger in a real, runnable flow — captured live from the Studio editor, exactly as it looks on your canvas. This is the same workflow used for the example input & output below.

Slack Trigger wired into a runnable workflow in the Studio builder — **Slack Trigger** wired into a runnable flow — input on the left, output on the right.

How it’s configured

The node’s settings as the builder shows them — every field laid out with real values. In the Studio these are edited on the node: click the chevron on the divider under its ports to open them.

The Slack Trigger node's settings in the Studio builder — The settings for **Slack Trigger**, showing the values from the flow above.

Ports

This is a trigger — it starts runs and takes no input wire.

Ports are the node’s contract with its neighbours. In the editor a port label renders bold when wired and italic when optional; ◈ ports accept attachment carriers rather than data wires.

Direction	Port	Label	What flows through it
Output	`output`	Event

How data flows through it

As a trigger, Slack Trigger starts runs — it takes no input wire. What it emits is the request wrapper: the event’s body becomes the payload, and the wrapper carries the event metadata around it (for an HTTP-style trigger that’s headers.*, request.method, request.path and query). Downstream nodes consume the content — the wrapper is unwrapped at each node boundary, and expression roots like {{ headers.x }} still resolve against the wrapper when you need the metadata. See Runs & run data for the envelope model.

Expressions in the config

String-typed properties accept {{ }} expressions evaluated against the incoming item at run time — e.g. {{ $json.customer.email }}. On this node that’s signingSecret, path. JSON- and code-typed fields never interpolate — they are passed through literally.

Build it with AI

Every node in this reference is reachable through Flowdrome’s AI Copilot and the MCP tools — say what you want, and the graph surgery happens server-side. Node types resolve fuzzily, so the catalog label (Slack Trigger) works as well as the exact type id (input.slack).

In the Copilot panel (or any connected AI):

create a workflow that starts with slack trigger and logs the result

As a step in a create_chain_workflow call:

{"type":"Slack Trigger","config":{}}

Raw MCP call — add this node to a workflow with add_node

curl -s -X POST http://localhost:4800/mcp -H "content-type: application/json" -d '{ "jsonrpc": "2.0", "id": "1", "method": "tools/call", "params": { "name": "add_node", "arguments": { "workflowId": "<id>", "type": "Slack Trigger" } } }'

Example input & output

Captured from a real test run of the workflow above — this is what the Runs view shows after pressing Test workflow.

Input — what the node received

The Slack Trigger node's input envelope in the run data viewer — The input envelope in the Runs view — Flowdrome always shows the whole envelope, with the payload inside `body`.

Output — what the node produced

The Slack Trigger node's output envelope in the run data viewer — The output envelope after the step ran.

Property reference

Every setting, with its type and default — the same fields shown configured above.

Property	Type	Default	Description
Credential `credentialId`	`credential`	`""`	Use a stored credential for this connection — its fields are filled in at run start. Pick "None" to enter the connection details manually. accepts credential templates: `slack-bot`
Signing secret `signingSecret`	`string`	`""`	Slack app signing secret — verifies the X-Slack-Signature HMAC on each inbound POST (serve mode).
Events path `path`	`string`	`"/slack/events"`	The local route Slack's Events API POSTs to.
Event filter `events`	`json`	`[]`	Only fire for these event types (e.g. ["message", "app_mention"]). Empty = all.
Ignore bots `ignoreBots`	`boolean`	`true`	Skip events produced by bots (bot_id present) so the bot doesn't answer itself.
Max body (bytes) `maxBodyBytes`	`int`	`1048576`	Largest request body this trigger accepts — bigger requests are rejected with 413 before the workflow runs. 0 = unlimited at the trigger (the app-wide FLOWDROME_MAX_BODY_BYTES ceiling, default 32 MB, still applies).
Rate limit (req/s) `rateLimitRps`	`double`	`0`	Per-client-IP sustained request rate for this trigger. 0 = no rate limit (the default). For internet-exposed apps, prefer rate limiting at a fronting reverse proxy (docs/ingress-guards-design.md).
Rate limit burst `rateLimitBurst`	`int`	`0`	How many requests a client may send back-to-back before the per-second rate applies. 0 = automatic (2× the rate). Shown when `(showIf === undefined \|\| showIf(c)) && Number(rateLimitRps ?? 0) > 0`

Related nodes

The rest of the Input group — the same folder you’d scan in the editor’s library.

This page is generated from the node registry by gen-node-docs.mjs on every site build — ports, properties, defaults and visibility rules cannot drift from the code. The screenshots and example data are captured from a live Flowdrome by npm run shots:nodes and npm run gen:examples.