HTTP Transport Support for MCP Server

[butschster]

Add HTTP transport support to the existing MCP server infrastructure by implementing transport selection via environment variables and creating necessary configuration DTOs.

Implementation Plan

1. HttpTransportConfig DTO

File: src/McpServer/HttpTransportConfig.php

<?php

declare(strict_types=1);

namespace Butschster\ContextGenerator\McpServer;

final readonly class HttpTransportConfig
{
    public function __construct(
        public string $host = 'localhost',
        public int $port = 8080,
        public string $sessionStore = 'file',
        public ?string $sessionStorePath = null,
        public bool $corsEnabled = true,
        public array $corsOrigins = ['*'],
        public int $maxRequestSize = 10485760, // 10MB
    ) {}

    public function getAddress(): string
    {
        return "http://{$this->host}:{$this->port}";
    }

    public function getSessionStoreConfig(): array
    {
        return [
            'type' => $this->sessionStore,
            'path' => $this->sessionStorePath,
        ];
    }
}

2. McpConfig Updates

Add HTTP transport configuration section and accessor methods:

// Add to protected array $config
'transport' => [
    'type' => 'stdio', // stdio|http
    'http' => [
        'host' => 'localhost',
        'port' => 8080,
        'session_store' => 'file',
        'session_store_path' => null,
        'cors_enabled' => true,
        'cors_origins' => ['*'],
        'max_request_size' => 10485760,
    ],
],

// Add accessor methods
public function getTransportType(): string
{
    return $this->config['transport']['type'] ?? 'stdio';
}

public function isHttpTransport(): bool
{
    return $this->getTransportType() === 'http';
}

public function getHttpTransportConfig(): HttpTransportConfig
{
    $http = $this->config['transport']['http'] ?? [];
    
    return new HttpTransportConfig(
        host: $http['host'] ?? 'localhost',
        port: (int)($http['port'] ?? 8080),
        sessionStore: $http['session_store'] ?? 'file',
        sessionStorePath: $http['session_store_path'] ?? null,
        corsEnabled: (bool)($http['cors_enabled'] ?? true),
        corsOrigins: $http['cors_origins'] ?? ['*'],
        maxRequestSize: (int)($http['max_request_size'] ?? 10485760),
    );
}

3. McpServerBootloader Updates

Add HTTP transport environment variables to init method:

// Add to $this->config->setDefaults() array
'transport' => [
    'type' => $env->get('MCP_TRANSPORT', 'stdio'),
    'http' => [
        'host' => $env->get('MCP_HTTP_HOST', 'localhost'),
        'port' => (int) $env->get('MCP_HTTP_PORT', 8080),
        'session_store' => $env->get('MCP_HTTP_SESSION_STORE', 'file'),
        'session_store_path' => $env->get('MCP_HTTP_SESSION_STORE_PATH'),
        'cors_enabled' => (bool) $env->get('MCP_HTTP_CORS_ENABLED', true),
        'cors_origins' => array_filter(explode(',', $env->get('MCP_HTTP_CORS_ORIGINS', '*'))),
        'max_request_size' => (int) $env->get('MCP_HTTP_MAX_REQUEST_SIZE', 10485760),
    ],
],

4. Server.php Updates

Modify the run method to use appropriate runner based on transport configuration:

public function run(string $name): void
{
    $server = new McpServer(name: $name, logger: $this->logger);
    $this->configureServer($server);

    $initOptions = $server->createInitializationOptions();
    
    // Determine transport type from environment or config
    $transportType = $_ENV['MCP_TRANSPORT'] ?? 'stdio';
    
    if ($transportType === 'http') {
        // Use HTTP runner with configuration
        $httpOptions = [
            'host' => $_ENV['MCP_HTTP_HOST'] ?? 'localhost',
            'port' => (int) ($_ENV['MCP_HTTP_PORT'] ?? 8080),
        ];
        
        $runner = new \Mcp\Server\HttpServerRunner(
            server: $server,
            initOptions: $initOptions,
            httpOptions: $httpOptions,
            logger: $this->logger
        );
        
        // Handle HTTP request if in HTTP mode
        $response = $runner->handleRequest();
        $runner->sendResponse($response);
    } else {
        // Use STDIO runner (default)
        $runner = new \Mcp\Server\ServerRunner(
            server: $server,
            initOptions: $initOptions,
            logger: $this->logger
        );
        $runner->run();
    }
}

Environment Variables

Transport Selection

• MCP_TRANSPORT=stdio|http - Transport type (default: stdio)

HTTP Transport Options

• MCP_HTTP_HOST=localhost - HTTP server host (default: localhost)
• MCP_HTTP_PORT=8080 - HTTP server port (default: 8080)
• MCP_HTTP_SESSION_STORE=file|memory - Session storage type (default: file)
• MCP_HTTP_SESSION_STORE_PATH=/path/to/sessions - Session storage path
• MCP_HTTP_CORS_ENABLED=true - Enable CORS (default: true)
• MCP_HTTP_CORS_ORIGINS=* - CORS allowed origins (comma-separated)
• MCP_HTTP_MAX_REQUEST_SIZE=10485760 - Max request size in bytes (default: 10MB)

Usage Examples

STDIO Mode (Default)

php app.php server
# or explicitly
MCP_TRANSPORT=stdio php app.php server

HTTP Mode

MCP_TRANSPORT=http php app.php server
# or with custom options
MCP_TRANSPORT=http MCP_HTTP_HOST=0.0.0.0 MCP_HTTP_PORT=3000 php app.php server