rs-mock-server 0.5.0

A simple, file-based mock API server that maps your directory structure to HTTP routes. Ideal for local development and testing.
rs-mock-server-0.5.0 is not a library.

rs-mock-server 🦀

A simple, zero-configuration mock server built in Rust. Spin up a realistic REST API for local development or testing just by creating folders and files.

It works by scanning a directory and mapping its structure directly to API routes, with clever filename conventions for handling HTTP methods, dynamic parameters, and static assets.

Features

  • 🚀 File-System Routing: Your folder structure defines your API routes. No config files needed.
  • 🧩 Dynamic Path Generation: Create routes with parameters ({id}), specific values ({admin}), and even numeric ranges ({1-10}) right from the filename.
  • ⚙️ Full HTTP Method Support: Define GET, POST, PUT, DELETE, PATCH, and OPTIONS endpoints.
  • 🔗 In-Memory REST API: Create fully functional CRUD APIs with automatic ID generation and data persistence during runtime using special rest.json files.
  • 🔐 JWT Authentication: Automatic authentication system with login/logout endpoints and route protection using special {auth} files.
  • 📤 File Upload & Download: Create upload endpoints with automatic file handling and download capabilities using special {upload} folders.
  • 🖼️ Static File Serving: Automatically serves any file (like images, CSS, or JS) with its correct Content-Type if the filename doesn't match a method pattern.
  • 🌐 Public Directory Serving: Serve a directory of static files (e.g., a frontend build) from a root public folder, or map a folder like public-assets to a custom /assets route.
  • 🔧 Configurable: Easily change the port and mock directory via command-line arguments.
  • ⚡ Lightweight & Fast: Built with Rust for minimal resource usage and maximum performance.

How It Works

The server recursively scans a root directory (defaults to ./mocks) and translates the file and folder paths into API endpoints.

Folder Structure → URL Path

The path of each folder becomes the base URL for the routes within it.

  • A folder at ./mocks/api/users creates the base route /api/users.
  • A nested folder at ./mocks/api/users/profiles creates the base route /api/users/profiles.

Filename Conventions → Endpoints

The name of a file determines the HTTP method and the final URL segment. The content of the file is served as the response body.

The following table shows how different filename patterns are mapped to routes, assuming they are inside a ./mocks/api/users directory:

Filename Pattern Example File Generated Route(s) Description
[method] get.json GET /api/users Creates a route for a standard HTTP method.
[method]{id}. get{id}.json GET /api/users/{id} A dynamic segment that accepts any value in that position.
[method]{value} get{admin}.json GET /api/users/admin Matches a specific, hardcoded value.
[method]{start-end} get{1-5}.json GET /api/users/1GET /api/users/2...GET /api/users/5 A numeric range that generates multiple distinct routes.
rest[{params}] rest.json GET /api/usersPOST /api/usersGET /api/users/{id}PUT /api/users/{id}PATCH /api/users/{id}DELETE /api/users/{id} In-Memory REST API. Creates a full CRUD API with automatic ID generation, data persistence, and initial data loading from the JSON array in the file.
{auth} {auth}.json POST /api/loginPOST /api/logout JWT Authentication. Creates login and logout endpoints with JWT token generation and validation middleware for route protection.
[filename].[ext] avatar.png GET /api/users/avatar Static File. Any filename that doesn't match the patterns above is served as a static asset. The Content-Type header is automatically set based on the file's extension.

In-Memory REST API

For rapid prototyping and testing, you can create fully functional CRUD APIs using special rest.json files. When the server detects a file named rest.json or rest{params}.json, it automatically:

  1. Loads initial data from the JSON array in the file
  2. Creates a complete REST API with all CRUD operations
  3. Maintains data in memory during the server's lifetime
  4. Handles ID generation automatically for new items

REST File Naming Convention

The {params} in the filename configures the ID field behavior:

Filename Pattern ID Key ID Type Example Usage
rest.json id UUID Default configuration
rest{uuid}.json id UUID Explicit UUID type
rest{int}.json id Integer Integer IDs starting from 1
rest{_id}.json _id UUID Custom ID field name with UUID
rest{_id:uuid}.json _id UUID Custom ID field name with explicit UUID type
rest{_id:int}.json _id Integer Custom ID field name with integer type

Generated Endpoints

For a rest.json file in ./mocks/api/products/, the following endpoints are automatically created:

Method Route Description
GET /api/products List all products
POST /api/products Create a new product (auto-generates ID)
GET /api/products/{id} Get a specific product by ID
PUT /api/products/{id} Update an entire product (replaces all fields)
PATCH /api/products/{id} Partially update a product (merges fields)
DELETE /api/products/{id} Delete a product by ID

Initial Data Format

The JSON file should contain an array of objects, where each object represents an item with the configured ID field:

[
    {
        "id": "550e8400-e29b-41d4-a716-446655440001",
        "name": "Wireless Headphones",
        "price": 199.99,
        "category": "Electronics"
    },
    {
        "id": "550e8400-e29b-41d4-a716-446655440002",
        "name": "Coffee Mug",
        "price": 15.99,
        "category": "Kitchen"
    }
]

For integer IDs using rest{_id:int}.json:

[
    {
        "_id": 1,
        "name": "Product One",
        "description": "First product"
    },
    {
        "_id": 2,
        "name": "Product Two",
        "description": "Second product"
    }
]

JWT Authentication

For applications requiring user authentication, you can create a complete JWT-based authentication system using special {auth} files. When the server detects a file named {auth}.json, it automatically:

  1. Loads user credentials from the JSON array in the file
  2. Creates authentication endpoints for login and logout
  3. Generates JWT tokens with secure cookies
  4. Provides middleware for protecting routes with authentication

Authentication File Detection

Only one authentication route is allowed per server instance. The {auth} file creates authentication endpoints based on its folder location:

File Location Generated Routes Description
./mocks/account/{auth}.json POST /account/loginPOST /account/logout Authentication for account management
./mocks/api/auth/{auth}.json POST /api/auth/loginPOST /api/auth/logout API authentication endpoints
./mocks/{auth}.json POST /loginPOST /logout Root-level authentication

Credentials File Format

The {auth}.json file should contain an array of user objects with username and password as required fields:

[
    {
        "id": "550e8400-e29b-41d4-a716-446655440001",
        "username": "admin",
        "password": "admin123",
        "email": "admin@example.com",
        "role": "administrator"
    },
    {
        "id": "550e8400-e29b-41d4-a716-446655440002",
        "username": "user",
        "password": "user123",
        "email": "user@example.com",
        "role": "user"
    },
    {
        "id": "550e8400-e29b-41d4-a716-446655440003",
        "username": "john.doe",
        "password": "password123",
        "email": "john.doe@example.com",
        "role": "user"
    }
]

Authentication Endpoints

Login Endpoint - POST /{folder}/login

  • Request: JSON with username and password
  • Response: JWT token and user info (password excluded)
  • Cookie: Sets HTTP-only auth_token cookie for 24 hours

Logout Endpoint - POST /{folder}/logout

  • Request: JWT token via Authorization header or cookie
  • Response: Success message
  • Action: Revokes the token from valid tokens list

Route Protection

To protect routes with authentication, prefix folder names or filenames with $:

Protected Files

mocks/
├── api/
│   ├── cities/
│   │   └── $get.json        # Protected: GET /api/cities
│   └── users/
│       └── get.json         # Public: GET /api/users

Protected Folders (protects all children)

mocks/
├── $admin/                  # All routes under /admin are protected
│   ├── users/
│   │   └── rest.json        # Protected: Full CRUD at /admin/users/*
│   └── settings/
│       └── get.json         # Protected: GET /admin/settings
└── open/
    └── info.json            # Public: GET /open/info

Authentication Examples

Login Request

curl -X POST http://localhost:4520/account/login \
  -H "Content-Type: application/json" \
  -d '{"username": "admin", "password": "admin123"}'

Login Response

{
    "token": "eyJ0eXAiOiJKV1QiLCJhbGciOiJIUzI1NiJ9...",
    "user": {
        "id": "550e8400-e29b-41d4-a716-446655440001",
        "username": "admin",
        "email": "admin@example.com",
        "role": "administrator"
    }
}

Accessing Protected Routes

Option A: Authorization Header

curl -H "Authorization: Bearer <jwt_token>" \
  http://localhost:4520/admin/users

Option B: Cookie (automatic)

curl -b "auth_token=<jwt_token>" \
  http://localhost:4520/admin/users

Logout Request

curl -X POST http://localhost:4520/account/logout \
  -H "Authorization: Bearer <jwt_token>"
  • It is not possible to protect a public folder

Security Features

  • JWT Tokens: 24-hour expiration with HS256 signing
  • HTTP-Only Cookies: Prevents XSS attacks
  • Token Revocation: Logout invalidates tokens
  • Dual Authentication: Supports Authorization header and cookies
  • Password Protection: Login responses exclude password fields
  • Route-Level Protection: Granular control over protected endpoints

Special "Public" Folder for Static Serving

To serve a directory of static assets (like a frontend app), you can use a specially named public folder in your mock directory root.

  • public folder: If you create a folder named public, all its contents will be served from the /public route.

    • ./mocks/public/home.html → GET /public/home.html

  • public-<alias> folder: You can customize the URL path by adding a dash. A folder named public-static will serve its files from the /static route.

    • ./mocks/public-static/style.css → GET /static/style.css

Special "{upload}" Folder for File Handling

For file upload and download functionality, you can create a specially named {upload} folder. When detected, the server automatically creates endpoints for uploading and downloading files.

Basic Upload Folder

  • {upload} folder: Creates upload and download endpoints at /upload.

    • POST /upload - Upload files (multipart/form-data)
    • GET /upload - List all uploaded files
    • GET /upload/{filename} - Download files by name

Upload Folder Configuration

The {upload} folder supports additional configuration through special naming patterns:

Folder Pattern Upload Route List Route Download Route Temporary Files Description
{upload} POST /upload GET /upload GET /upload/{filename} No Basic upload/download
{upload}{temp} POST /upload GET /upload GET /upload/{filename} Yes Files deleted on server stop
{upload}-files POST /files GET /files GET /files/{filename} No Custom route name
{upload}{temp}-docs POST /docs GET /docs GET /docs/{filename} Yes Custom route + temporary

Examples

  • Basic: ./mocks/{upload}/ creates POST /upload, GET /upload, and GET /upload/{filename}
  • Temporary: ./mocks/{upload}{temp}/ - same endpoints, but files are cleaned up when server stops
  • Custom Route: ./mocks/{upload}-files/ creates POST /files, GET /files, and GET /files/{filename}
  • Combined: ./mocks/{upload}{temp}-upfiles/ creates POST /upfiles, GET /upfiles, and GET /upfiles/{filename} with automatic cleanup

All uploaded files are saved in the detected folder with their original filenames, and downloads include proper Content-Type and Content-Disposition headers.

Installation

With Cargo

You can install it directly:

cargo install rs-mock-server

From Source

Alternatively, you can clone the repository and build it yourself:

# Clone the repository
git clone https://github.com/lvendrame/rs-mock-server.git

# Navigate into the project directory
cd rs-mock-server

# Build the project for release
cargo build --release

# The executable will be at ./target/release/rs-mock-server
./target/release/rs-mock-server --help

Usage

You can run the server using the rs-mock-server executable.

To start the server with default settings: (This will use the ./mocks folder and run on port 4520)

rs-mock-server

To specify a custom port and mock directory:

rs-mock-server --port 8080 --folder ./my-api-mocks

Command-Line Options

Usage: rs-mock-server [OPTIONS]

Options:
  -p, --port <PORT>      Port to run the server on [default: 4520]
  -f, --folder <FOLDER>  Directory to load mock files from [default: mocks]
  -h, --help             Print help
  -V, --version          Print version

Example Walkthrough

Imagine you have the following directory structure:

mocks/
├── api/
│   ├── users/
│   │   ├── get.json         # Contains a JSON array of all users
│   │   ├── post.json        # Contains a success message for user creation
│   │   └── get{id}.json    # Contains a single user object template
│   ├── products/
│   │   ├── rest{_id:int}.json # In-memory REST API with integer IDs
│   │   ├── get{1-3}.json   # Contains a product template for IDs 1, 2, 3
│   │   └── get{special}.json# Contains a specific "special" product
│   ├── companies/
│   │   └── rest.json        # In-memory REST API with UUID IDs
│   ├── auth/
│   │   └── {auth}.json      # JWT authentication with user credentials
│   └── status.txt           # Contains the plain text "API is running"
├── $admin/                  # Protected folder - requires authentication
│   └── settings/
│       └── get.json         # Protected admin settings
├── assets/
│   └── logo.svg             # An SVG image file
├── {upload}/                # Upload folder for file handling
├── {upload}{temp}-docs/     # Temporary upload folder with custom route
└── public-static/
    ├── image.jpg            # An JPG image file
    └── css/
        └── style.css        # A stylesheet

Running rs-mock-server in the same directory will create the following endpoints:

Method Route Response Body From... Content-Type Description
GET /api/users mocks/api/users/get.json application/json Static response
POST /api/users mocks/api/users/post.json application/json Static response
GET /api/users/{id} mocks/api/users/get{id}.json application/json Static response
GET /api/products In-memory data from rest{_id:int}.json application/json REST API - List all products
POST /api/products In-memory database application/json REST API - Create new product
GET /api/products/{_id} In-memory database application/json REST API - Get product by ID
PUT /api/products/{_id} In-memory database application/json REST API - Update product
PATCH /api/products/{_id} In-memory database application/json REST API - Partial update
DELETE /api/products/{_id} In-memory database application/json REST API - Delete product
GET /api/products/1 mocks/api/products/get{1-3}.json application/json Static response
GET /api/products/2 mocks/api/products/get{1-3}.json application/json Static response
GET /api/products/3 mocks/api/products/get{1-3}.json application/json Static response
GET /api/products/special mocks/api/products/get{special}.json application/json Static response
GET /api/companies In-memory data from rest.json application/json REST API - List all companies
POST /api/companies In-memory database application/json REST API - Create new company
GET /api/companies/{id} In-memory database application/json REST API - Get company by ID
PUT /api/companies/{id} In-memory database application/json REST API - Update company
PATCH /api/companies/{id} In-memory database application/json REST API - Partial update
DELETE /api/companies/{id} In-memory database application/json REST API - Delete company
GET /api/status mocks/api/status.txt text/plain Static file
POST /api/auth/login JWT authentication application/json Auth - Login with credentials
POST /api/auth/logout JWT token revocation application/json Auth - Logout and revoke token
GET /admin/settings mocks/$admin/settings/get.json application/json Protected - Requires authentication
GET /assets/logo mocks/assets/logo.svg image/svg+xml Static file
POST /upload File upload handling text/plain Upload - Upload files
GET /upload List of uploaded files application/json Upload - List uploaded files
GET /upload/{filename} Files from {upload}/ folder varies Download - Download files
POST /docs File upload handling (temporary) text/plain Upload - Upload files (temp)
GET /docs List of uploaded files (temporary) application/json Upload - List uploaded files
GET /docs/{filename} Files from {upload}{temp}-docs/ folder varies Download - Download files (temp)
GET /static/image.jpg mocks/public-static/image.svg image/jpg Static file
GET /static/css/style.css mocks/public-static/css/style.css text/css Static file

Note:

  • The REST API endpoints provide full CRUD functionality with automatic ID generation, data persistence during runtime, and initial data loading from the JSON files.
  • Authentication endpoints provide JWT-based login/logout with secure token management and route protection capabilities.
  • Protected routes (prefixed with $) require valid JWT tokens via Authorization header or auth_token cookie.
  • Upload endpoints handle multipart/form-data file uploads and preserve original filenames.
  • Download endpoints serve files with proper Content-Type detection and Content-Disposition headers.
  • Temporary upload folders ({temp}) automatically clean up all files when the server stops.
  • You can interact with all endpoints using any HTTP client, and data will persist until the server is restarted.