Inngest Durable Functions

Inngest Durable Functions

Master Inngest's durable execution model for building fault-tolerant, long-running workflows. This skill covers the complete lifecycle from triggers to error handling.

These skills are focused on TypeScript. For Python or Go, refer to the Inngest documentation for language-specific guidance. Core concepts apply across all languages.

Core Concepts You Need to Know

Durable Execution Model

• Each step should encapsulate side-effects and non-deterministic code
• Memoization prevents re-execution of completed steps
• State persistence survives infrastructure failures
• Automatic retries with configurable retry count

Step Execution Flow

// ❌ BAD: Non-deterministic logic outside steps
async ({ event, step }) => {
  const timestamp = Date.now(); // This runs multiple times!

  const result = await step.run("process-data", () => {
    return processData(event.data);
  });
};

// ✅ GOOD: All non-deterministic logic in steps
async ({ event, step }) => {
  const result = await step.run("process-with-timestamp", () => {
    const timestamp = Date.now(); // Only runs once
    return processData(event.data, timestamp);
  });
};

Function Limits

Every Inngest function has these hard limits: