Mockbox

A flexible HTTP proxy server powered by Rune scripting. Every incoming request is first handled by a Rune script, which can either respond directly or indicate that the request should be proxied to an upstream server.

Features

• Rune Scripting: Handle HTTP requests with dynamic Rune scripts
• Upstream Proxy: Automatically proxy unhandled requests to another web server
• Hot-reloadable: Modify scripts without restarting
• Full HTTP Support: Access method, path, headers, and body in scripts

Installation

Pre-Built Binaries

You can download pre-built binaries from the latest release.

From Source

1. Clone the repository
2. Build the project:

cargo install mockbox

Usage

Basic Setup

1. Generate the an example script:

mockbox example > mockbox.rn

2. Run the server:

mockbox mock

If no script path is passed to mockbox, it will check for a file called mockbox.rn in the current directory and if it doesn't exist, it will check in $HOME/.local/share/mockbox for a mockbox.rn.

3. The server will start on http://127.0.0.1:3333

Configuration

Configure the upstream server using the MOCKBOX_UPSTREAM environment variable:

MOCKBOX_UPSTREAM=http://localhost:8080 mockbox mock mockbox.rn

or by using the appropriate cli option:

mockbox mock mockbox.rn --upstream http://localhost:8080

Rune Script API

Your mockbox.rn must export a handle_request function that receives a request object and returns either a string, an object, a tuple ((<statuscode>, <response>)).

Request Object

The request object passed to your handler contains:

• method: HTTP method (e.g., "GET", "POST")
• path: Request path (e.g., "/api/users")
• body: Request body as a string

Response Options

1. Return a simple string

Return just a string for a 200 OK response:

pub fn handle_request(request) {
    "Hello, World!"
}

2. Return an object

Return an object for a 200 OK response:

pub fn handle_request(request) {
    #{some: 1, values: 2}
}

The object will automatically be converted to json.

3. Return status and response

Return a tuple with status and response (string or object):

pub fn handle_request(request) {
    (200, "Hello, World!")
}

4. Proxy to upstream server

Explicitly return nothing to proxy the request:

pub fn handle_request(request) {
    ()
}

Example Scripts

Mock API Endpoints

pub fn handle_request(request) {
    let path = request.path;
    let method = request.method;

    // Mock user API
    match path {
        "/api/users" if method == "GET" => {
            [#{ "id": 1, "name": "John" }, #{ "id": 2, "name": "Jane" }]
        }

        // Mock authentication
        "/api/login" if method == "POST" => {
            #{ "token": "mock-jwt-token-12345" }
        }
    }
}

Route-based Handling

pub fn handle_request(request) {
    let path = request.path;

    match path {
        // Echo endpoint
        "/echo" => request.body,

        // Handle all /mock/* routes
        _ if path.starts_with("/mock/") => #{mocked: true, path: path},
    }
}

Conditional Mocking

pub fn handle_request(request) {
    let path = request.path;
    let body = request.body;

    // Mock only if body contains "test"
    if body.contains("test") {
        return #{ "message": "Test mode response" };
    }
}

Error Responses

pub fn handle_request(request) {
    let path = request.path;

    // Simulate errors for testing
    match path {
        "/error/500" => (500, "Internal Server Error"),
        "/error/404" => (404, "Not Found"),
    }
}

Architecture

1. Request Reception: Axum receives the HTTP request
2. Rune Execution: The handle_request function in mockbox.rn is called
3. Response Decision:
   • If the script returns a string, object or response tuple → respond directly
   • If the script doesn't return anything or explicitly returns () → proxy to upstream server
4. Upstream Proxy: Forward the original request to the configured upstream URL
5. Response: Return the response from either Rune or the upstream server

Use Cases

• Mock APIs: Create mock responses for testing frontend applications
• Request Interception: Log, modify, or reject requests based on conditions
• A/B Testing: Route requests to different backends based on rules
• Development Environment: Override specific endpoints while keeping others real

Testing

Test your Rune scripts by making HTTP requests:

# Test a mocked endpoint

curl http://localhost:3333/hello


# Test the upstream proxy

curl http://localhost:3333/some/real/path

Optional Features

storage

Enables the storage API to persist data between requests.

This is disabled by default, because it currently uses a blocking RwLock to synchronize access.

// store a rune value
storage::set(key, value)

// load a stored value
storage::get(key)

// delete a stored value
storage::delete(key)

// check if a value exists
storage::has(key)

// clear the whole storage
storage::clear()

// get keys of all stored values
storage::keys()