Actions Registry (alpha)

Overview

The Actions Registry Service is a core service designed to provide a distributed registry for actions that can be executed within Backstage backend plugins. This service allows plugins to register reusable actions with well-defined schemas and execution logic, promoting consistency and reusability across the Backstage ecosystem.

Action Structure

Each action registered with the service must conform to the ActionsRegistryActionOptions type, which includes:

Required Properties

• name: A unique identifier for the action (string)
• title: A human-readable title for the action (string)
• description: A detailed description of what the action does (string)
• schema: Object containing input and output schema definitions
  • input: Function that returns a Zod schema for validating input
  • output: Function that returns a Zod schema for validating output
• action: The async function that executes the action logic

Optional Properties

• attributes: Object containing behavioral flags:
  • destructive: Boolean indicating if the action modifies or deletes data
  • idempotent: Boolean indicating if running the action multiple times produces the same result
  • readOnly: Boolean indicating if the action only reads data without modifications

Action Context

When an action is executed, it receives a context object (ActionsRegistryActionContext) containing:

• input: The validated input data matching the defined input schema
• logger: A LoggerService instance for logging within the action
• credentials: BackstageCredentials for authentication and authorization

Using the Service

Registering an Action

Here's an example of how to register an action with the Actions Registry Service:

import { ActionsRegistryService } from '@backstage/backend-plugin-api';

export function registerMyActions(actionsRegistry: ActionsRegistryService) {
  // Register a simple read-only action
  actionsRegistry.register({
    name: 'fetch-user-info',
    title: 'Fetch User Information',
    description: 'Retrieves user information from the catalog',
    schema: {
      input: z =>
        z.object({
          userRef: z.string(),
          includeGroups: z.boolean().optional(),
        }),
      output: z =>
        z.object({
          user: z.object({
            name: z.string(),
            email: z.string(),
            groups: z.array(z.string()).optional(),
          }),
        }),
    },
    attributes: {
      readOnly: true,
      idempotent: true,
    },
    action: async ({ input, logger, credentials }) => {
      logger.info(`Fetching user info for ${input.userRef}`);

      // Perform the action logic here
      const user = await fetchUserFromCatalog(input.userRef, credentials);

      return {
        output: {
          user: {
            name: user.name,
            email: user.email,
            groups: input.includeGroups ? user.groups : undefined,
          },
        },
      };
    },
  });

  // Register a destructive action
  actionsRegistry.register({
    name: 'delete-entity',
    title: 'Delete Entity',
    description: 'Removes an entity from the catalog',
    schema: {
      input: z =>
        z.object({
          entityRef: z.string(),
          force: z.boolean().optional(),
        }),
      output: z =>
        z.object({
          deletedEntities: z.array(z.string()),
        }),
    },
    attributes: {
      destructive: true,
      idempotent: false,
    },
    action: async ({ input, logger, credentials }) => {
      logger.warn(`Deleting entity ${input.entityRef}`);

      // Perform the deletion logic here
      const { deletedEntities } = await deleteEntityFromCatalog(
        input.entityRef,
        input.force,
        credentials,
      );

      return {
        output: deletedEntities,
      };
    },
  });
}

Accessing the Service in a Plugin

To use the Actions Registry Service in your plugin, access it through dependency injection:

import {
  createBackendPlugin,
  coreServices,
} from '@backstage/backend-plugin-api';

export const myPlugin = createBackendPlugin({
  pluginId: 'my-plugin',
  register(env) {
    env.registerInit({
      deps: {
        actionsRegistry: coreServices.actionsRegistry,
        logger: coreServices.logger,
      },
      async init({ actionsRegistry, logger }) {
        logger.info('Registering actions...');
        registerMyActions(actionsRegistry);
        logger.info('Actions registered successfully');
      },
    });
  },
});

Best Practices

Naming Conventions

• Use kebab-case: Action names should be in kebab-case (e.g., fetch-user-info, create-repository)
• Be Descriptive: Choose names that clearly describe what the action does
• Avoid Redundancy: Don't include plugin names in action names since the plugin context is separate
• Use Verbs: Start action names with verbs that describe the operation (e.g., fetch, create, delete, update)

Action Attributes Reference

Attribute	Type	Default	Description
destructive	boolean	true	Indicates the action modifies or deletes data. Use with caution.
idempotent	boolean	false	Indicates the action can be run multiple times with the same result
readOnly	boolean	false	Indicates the action only reads data without making modifications

These attributes help consumers of actions understand their behavior and implement appropriate safeguards, retries, or optimizations based on the action's characteristics.