Backstage Scaffolder Custom Action Not Found

In this tutorial, you'll learn about Backstage Scaffolder Custom Action Not Found. We cover key concepts, practical examples, and best practices to help you understand and apply this topic effectively.

A custom scaffolder action you registered never appears in the template picker or returns a 500 error when invoked.

Wrong ❌

// actions/customAction.ts
export const createCustomAction = () => {
  return {
    id: 'custom:action',
    description: 'My custom action',
    schema: {
      input: {
        required: ['param1'],
        type: 'object',
        properties: {
          param1: { type: 'string' }
        }
      },
    },
    async handler(ctx) {
      // Missing ctx.logger and error handling
      throw new Error('Not implemented');
    },
  };
};

Wrong Output

Template execution failed: Action 'custom:action' not found.
Available actions: fetch:template, fetch:plain, debug:log, ...

Right ✅

// actions/customAction.ts
import { createTemplateAction } from '@backstage/plugin-scaffolder-node';

export const createCustomAction = () => {
  return createTemplateAction({
    id: 'custom:action',
    description: 'Creates a config file from input parameters',
    schema: {
      input: {
        required: ['param1'],
        type: 'object',
        properties: {
          param1: { type: 'string', description: 'Configuration key' },
        },
      },
    },
    async handler(ctx) {
      ctx.logger.info(`Running custom:action with ${ctx.input.param1}`);
      ctx.output('result', `Processed ${ctx.input.param1}`);
    },
  });
};

Right Output

Executing step: custom:action
Step completed successfully.
Output: result = "Processed my-value"

Prevention

• Register your custom action in the scaffolder module: scaffolder.actions.push(createCustomAction()).
• Verify the action ID matches the one referenced in the template step definition.
• Add proper error handling and logging within the handler for debugging.
• Test the action locally using the scaffolder standalone runner.
• Include a schema with proper descriptions for all input parameters to improve UX.

DodaTech applies similar defensive patterns across Doda Browser, DodaZIP, and Durga Antivirus Pro infrastructure for production reliability.

Common Mistakes with scaffolder action

1. Forgetting that lazy evaluation defers computation until the value is forced, causing space leaks with unevaluated thunks
2. Using return to exit a function early instead of wrapping a pure value in the monad
3. Mixing let bindings with <- bindings in do notation, producing type errors

These mistakes appear frequently in real-world BACKSTAGE code. DodaTech's contributors have identified these patterns through analysis of open-source projects and production systems.

Practice Exercise

Write a pure function that safely divides two integers using Maybe, then test it with edge cases like division by zero and negative numbers.

This exercise reinforces the concepts covered in this guide. Try implementing it before checking online solutions.

FAQ

This quick fix is part of the DodaTech infrastructure engineering series. Learn more at DodaTech tutorials.