Functions

Using an AI coding assistant? Connect Cursor, Claude, or Copilot to Snag Docs for context-aware help. Learn how.

Overview

Stratus functions enable developers to write and execute JavaScript functions in a serverless environment. These functions:

Scale horizontally
Run in isolated VMs
Have web access for external integrations
Support complex logic combinations

Functions can interact with external services, allowing you to integrate with your own database, subgraphs, and other services.

Invocation Types

Schedule

Execute functions on a cron schedule with minimum 1-minute resolution

Webhook

Invoke functions via HTTP POST requests using API keys

Subscription

Trigger functions automatically when subscribed events occur

Schedule Invocation

While there's no maximum schedule limit, the minimum resolution is 1 minute. Schedules with smaller intervals will fail.

Webhook Invocation

To invoke functions via webhook:

Create a Stratus-scoped API key in the admin panel
Use the unique webhook URL assigned to your function

Webhook Example

curl --request POST \
  --url https://admin.snagsolutions.io/api/stratus/functions/<functionID>/invoke \
  --header 'Content-Type: application/json' \
  --header 'X-API-KEY: <stratus_api_key>' \
  --data '{
    "organizationId": "org-1234",
    "websiteId": "site-5678",
    "input": {
      "foo": 123,
      "bar": "example value"
    }
  }'

Subscription Invocation

Functions linked to subscriptions execute automatically when subscription events fire. Unlike webhooks, subscription-based invocations receive a single payload per event.

Writing Functions

Basic Structure

All Stratus functions must follow these rules:

Export Single Handler

Only one handler function can be exported per file

Use Async Function

Handlers must be asynchronous

Include Required Parameters

Functions must accept input and output parameters

Basic Template

module.exports.handler = async (input, output) => {
  // Your function logic here
};

The Output Class

The output parameter provides methods for managing function results and actions:

setResultfunction

Sets the function result data (called once before buildOutput)

setResult(resultObject: Record<string, any>): void

setErrorfunction

Logs a failure and stops future executions

setError(error: string): void

addTransactionfunction

Adds a transaction to the execution queue (requires relayer connection)

addTransaction(tx: Pick<SendTransactionParameters, 'to' | 'data' | 'value'>): void

buildOutputfunction

Finalizes and returns the function output (required)

buildOutput(): Record<string, any>

Executing Transactions

To execute transactions, your function must be connected to a relayer in your account.

Transaction Rules

Maximum 500 transactions per function run
Transactions execute in the order they're added
All transactions use the connected relayer

Approved Modules

Only pre-approved npm modules can be used in Stratus functions. Contact Snag Solutions if you need additional modules.

Currently approved modules:

axios
lodash
viem
ioRedis
upstash/redis

Example Function

const axios = require('axios');

module.exports.handler = async (input, output) => {
  try {
    // Make an external API call
    const response = await axios.get('https://api.example.com/data');
    
    // Set the result
    output.setResult({ 
      data: response.data,
      timestamp: Date.now()
    });

    // Add a transaction if needed
    output.addTransaction({
      to: '0x123...',
      data: '0x456...',
      value: '0'
    });

    // Return the built output
    return output.buildOutput();
  } catch (error) {
    output.setError(`Function failed: ${error.message}`);
    return output.buildOutput();
  }
};

Need Additional Modules?

Contact Snag Solutions if you need access to additional npm modules for your Stratus functions.

Function Syntax

Reference guide for exports, parameters, and module imports.

Function Templates

Pre-built templates for airdrops, token gating, and rewards.

Subscriptions

Trigger functions automatically from onchain events.

Loyalty Overview

Configure the loyalty program that functions can interact with.