Authentication | Fern Documentation

Configuring authentication schemes happens in the components.securitySchemes section of AsyncAPI.

asyncapi.yml

components: 
  securitySchemes: 
    ...

To apply a security scheme across all operations, reference the securityScheme within the security section of your AsyncAPI Specification.

asyncapi.yml

components: 
  securitySchemes: 
    AuthScheme:
      ...
security: 
  - AuthScheme: []

Bearer security scheme

Start by defining a bearer security scheme in your asyncapi.yml:

asyncapi.yml

components:
  securitySchemes:
    BearerAuth:
      type: http
      scheme: bearer

This will generate an SDK where the user would have to provide a mandatory argument called token.

index.ts

const client = new Client({
  token: "ey34..."
})

If you want to control variable naming and the environment variable to scan, use the configuration below:

asyncapi.yml

components:
  securitySchemes:
    BearerAuth:
      type: http
      scheme: bearer
      x-fern-token:
        name: authToken
        env: AUTH_TOKEN

API key security scheme

Start by defining an apiKey security scheme in your asyncapi.yml:

asyncapi.yml

components:
  securitySchemes:
    ApiKeyAuth:
      type: apiKey
      in: header
      name: X-API-Key

This will generate an SDK where the user would have to provide a mandatory argument called apiKey.

index.ts

const client = new Client({
  apiKey: "my-api-key"
})

Custom API key variable name

If you want to control variable naming and the environment variable to scan, use the configuration below:

asyncapi.yml

components:
  securitySchemes:
    ApiKeyAuth:
      type: apiKey
      x-fern-api-key:
        name: customApiKey
        env: CUSTOM_API_KEY
      in: header
      name: X-API-Key

Basic security scheme

Start by defining a basic security scheme in your asyncapi.yml:

asyncapi.yml

components:
  securitySchemes:
    BasicAuth:
      type: http
      scheme: basic

This will generate an SDK where the user would have to provide a username and password.

index.ts

const client = new Client({
  username: "john@example.com",
  password: "password123"
})

Custom basic auth variable names

If you want to control variable naming and the environment variables to scan, use the configuration below:

asyncapi.yml

components:
  securitySchemes:
    BasicAuth:
      type: http
      scheme: basic
      x-fern-username:
        name: email
        env: EMAIL
      x-fern-password:
        name: pass
        env: PASSWORD

OAuth2 security scheme

OAuth2 authentication is supported for AsyncAPI specifications:

asyncapi.yml

components:
  securitySchemes:
    OAuth2:
      type: oauth2
      flows:
        authorizationCode:
          authorizationUrl: https://example.com/oauth/authorize
          tokenUrl: https://example.com/oauth/token
          scopes:
            read: Read access to resources
            write: Write access to resources

This will generate an SDK that supports OAuth2 flow for event-driven operations.

Multiple security schemes

You can specify multiple security schemes and apply them to different operations:

asyncapi.yml

components:
  securitySchemes:
    ApiKeyAuth:
      type: apiKey
      in: header
      name: X-API-Key
    BearerAuth:
      type: http
      scheme: bearer
    OAuth2:
      type: oauth2
      flows: ...
operations:
  sendMessage:
    security:
      - ApiKeyAuth: []
      - BearerAuth: []

This allows different operations to use different authentication methods as needed.