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CBA Sample Practice Questions

Practice Resources

Software Catalog (25%)

Question 1

What are the main entity kinds in Backstage Software Catalog?

Show Solution Main entity kinds: - **Component** - A piece of software (service, website, library) - **API** - A boundary between components - **Resource** - Infrastructure (database, S3 bucket) - **System** - Collection of components and resources - **Domain** - Collection of systems - **Group** - Team or organizational unit - **User** - Individual person - **Location** - Reference to other catalog files

Question 2

Write a catalog-info.yaml for a backend service.

Show Solution 
apiVersion: backstage.io/v1alpha1
kind: Component
metadata:
  name: my-backend-service
  description: Backend API service
  tags:
    - java
    - spring-boot
  annotations:
    github.com/project-slug: my-org/my-backend
    backstage.io/techdocs-ref: dir:.
spec:
  type: service
  lifecycle: production
  owner: team-backend
  system: my-system
  providesApis:
    - my-api
  dependsOn:
    - resource:my-database

Question 3

How do you define relationships between entities?

Show Solution Relationships are defined in the `spec` section: 
spec:
  # Component relationships
  owner: team-name           # Group that owns this
  system: system-name        # System this belongs to
  providesApis:              # APIs this component provides
    - api-name
  consumesApis:              # APIs this component uses
    - other-api
  dependsOn:                 # Dependencies
    - component:other-service
    - resource:database

  # System relationships
  domain: domain-name        # Domain this system belongs to

Software Templates (20%)

Question 4

Create a basic Software Template for scaffolding a new service.

Show Solution 
apiVersion: scaffolder.backstage.io/v1beta3
kind: Template
metadata:
  name: create-service
  title: Create New Service
  description: Create a new microservice
spec:
  owner: platform-team
  type: service
  parameters:
    - title: Service Details
      required:
        - name
        - owner
      properties:
        name:
          title: Service Name
          type: string
        owner:
          title: Owner
          type: string
          ui:field: OwnerPicker
        description:
          title: Description
          type: string
  steps:
    - id: fetch
      name: Fetch Template
      action: fetch:template
      input:
        url: ./skeleton
        values:
          name: ${{ parameters.name }}
          owner: ${{ parameters.owner }}
    - id: publish
      name: Publish to GitHub
      action: publish:github
      input:
        repoUrl: github.com?owner=my-org&repo=${{ parameters.name }}
    - id: register
      name: Register in Catalog
      action: catalog:register
      input:
        repoContentsUrl: ${{ steps.publish.output.repoContentsUrl }}
        catalogInfoPath: /catalog-info.yaml
  output:
    links:
      - title: Repository
        url: ${{ steps.publish.output.remoteUrl }}

Question 5

What are common template actions?

Show Solution Common built-in actions: - `fetch:template` - Fetch and render a template - `fetch:plain` - Fetch files without templating - `publish:github` - Create GitHub repository - `publish:gitlab` - Create GitLab repository - `catalog:register` - Register entity in catalog - `catalog:write` - Write catalog-info.yaml - `debug:log` - Log debug information - `fs:delete` - Delete files - `fs:rename` - Rename files

TechDocs (12%)

Question 6

How do you configure TechDocs for a component?

Show Solution 1. Add annotation to catalog-info.yaml: 
metadata:
  annotations:
    backstage.io/techdocs-ref: dir:.
2. Create docs folder with mkdocs.yml: 
site_name: My Service Docs
nav:
  - Home: index.md
  - API: api.md
plugins:
  - techdocs-core
3. Create docs/index.md with content.

Question 7

What are the TechDocs generation strategies?

Show Solution **Local** - Generate docs on Backstage server 
techdocs:
  builder: 'local'
  generator:
    runIn: 'local'
**External** - Generate in CI/CD, store externally 
techdocs:
  builder: 'external'
  publisher:
    type: 'awsS3'
    awsS3:
      bucketName: 'my-techdocs-bucket'

Plugins (15%)

Question 8

What is the Backstage plugin architecture?

Show Solution Backstage has three plugin types: 1. **Frontend Plugins** - React components for UI - Pages, cards, tabs - Run in browser 2. **Backend Plugins** - Node.js services - APIs, processors - Run on server 3. **Common Plugins** - Shared code - Types, utilities - Used by both frontend and backend Plugin structure: 
plugins/
├── my-plugin/           # Frontend plugin
│   ├── src/
│   └── package.json
├── my-plugin-backend/   # Backend plugin
│   ├── src/
│   └── package.json
└── my-plugin-common/    # Shared code
    ├── src/
    └── package.json

Question 9

How do you install a community plugin?

Show Solution 
# Install frontend plugin
yarn add --cwd packages/app @backstage/plugin-<name>

# Install backend plugin
yarn add --cwd packages/backend @backstage/plugin-<name>-backend

# Add to app
# packages/app/src/App.tsx
import { MyPluginPage } from '@backstage/plugin-my-plugin';

// Add route
<Route path="/my-plugin" element={<MyPluginPage />} />

Architecture (18%)

Question 10

What are the main components of Backstage architecture?

Show Solution 1. **App** - Frontend React application 2. **Backend** - Node.js backend services 3. **Catalog** - Entity database and API 4. **Scaffolder** - Template execution engine 5. **TechDocs** - Documentation system 6. **Search** - Search functionality 7. **Auth** - Authentication providers Database: PostgreSQL (production) or SQLite (development)

Question 11

How does catalog ingestion work?

Show Solution Catalog ingestion process: 1. **Location** entities point to catalog files 2. **Entity Providers** fetch catalog files 3. **Processors** transform and validate entities 4. **Stitching** resolves relationships 5. **Database** stores final entities Location types: - `url` - HTTP/HTTPS URLs - `file` - Local file paths - `github-discovery` - Auto-discover from GitHub

Customization (10%)

Question 12

How do you customize the Backstage theme?

Show Solution 
// packages/app/src/App.tsx
import { createTheme, lightTheme } from '@backstage/theme';

const myTheme = createTheme({
  palette: {
    ...lightTheme.palette,
    primary: {
      main: '#1DB954',
    },
    navigation: {
      background: '#171717',
      indicator: '#1DB954',
    },
  },
});

// Use in app
<ThemeProvider theme={myTheme}>
  <App />
</ThemeProvider>

Exam Tips

  1. Know entity kinds - Component, API, Resource, System, Domain
  2. Understand catalog-info.yaml - Structure and annotations
  3. Practice template syntax - Parameters, steps, actions
  4. Know TechDocs setup - mkdocs.yml, annotations
  5. Understand plugin architecture - Frontend, backend, common

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