Fern Definition

Overview

A Fern Definition is a set of YAML files that describe your API.

Each Fern Definition file may define:

  • Custom types. Use custom types to build your data model.
  • Endpoints. Group related endpoints into services.
  • Errors. An error represents a failed (non-200) response from an endpoint.

An example of a Fern Definition

imdb.yml
1service:
2  auth: false
3  base-path: /movies
4  endpoints:
5    createMovie:
6      docs: Add a movie to the database
7      method: POST
8      path: /create-movie
9      request: CreateMovieRequest
10      response: MovieId
11
12    getMovie:
13      method: GET
14      path: /{movieId}
15      path-parameters:
16        movieId: MovieId
17      response: Movie
18      errors:
19        - NotFoundError
20        - UnauthorizedError
21
22types:
23  Movie:
24    properties:
25      title: string
26      rating:
27        type: double
28        docs: The rating scale from one to five stars
29      id:
30        type: MovieId
31        docs: The unique identifier for a movie
32
33  CreateMovieRequest:
34    properties:
35      title: string
36      rating: double
37
38errors:
39  NotFoundError:
40    http:
41      statusCode: 404
42    type:
43      properties:
44        id: MovieId
45
46  UnauthorizedError:
47    http:
48      statusCode: 401
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