Architecture Overview

Architecture Overview

The MCP Gateway (ContextForge) is a production-grade gateway, proxy, and registry for Model Context Protocol (MCP) servers and A2A Agents. It acts as a unified entry point for tools, resources, prompts, and servers, federating local and remote nodes into a coherent MCP-compliant interface.

High-Level Architecture Summary

MCP Gateway (ContextForge) is a comprehensive production-grade gateway built on modern Python technologies with a performance-first approach. For a detailed visual diagram of the high-performance components (Rust-powered libraries, async patterns, caching layers, and Kubernetes scaling), see the Performance Architecture Diagram.

Design Diagrams

The following diagrams are generated by make docs and provide a quick visual reference for the codebase structure:

Core Technology Stack

1. Python FastAPI Application with Modern Stack

• Built with FastAPI (async web framework) for high-performance REST/JSON-RPC endpoints
• Uses Pydantic 2.11+ for runtime validation and Pydantic Settings for environment-based configuration
• Requires Python 3.11-3.13 with full async/await support throughout
• Deployed via Uvicorn (dev) or Gunicorn (production) ASGI servers

2. Multi-Database ORM Layer with SQLAlchemy 2.0

• SQLAlchemy 2.0 ORM with async support for database operations
• Supports PostgreSQL (via psycopg3), SQLite (default, file-based), and MariaDB/MySQL (via pymysql)
• Alembic for schema migrations and version control
• Connection pooling with configurable pool sizes (200 default), overflow (10), and recycling (3600s)

3. Multi-Transport Protocol Gateway

• Native MCP (Model Context Protocol) server implementation supporting protocol version 2025-03-26
• Transport mechanisms: HTTP/JSON-RPC, Server-Sent Events (SSE) with keepalive, WebSocket, stdio (for CLI integration), and streamable-HTTP
• JSON-RPC 2.0 compliant message handling with bidirectional communication

4. Federation & Registry Architecture

• Acts as an MCP Registry that federates multiple peer gateways
• Auto-discovery via mDNS/Zeroconf or manual configuration
• Redis-backed caching and federation for multi-cluster deployments (optional, can use memory or database caching)
• Health checking with configurable intervals (60s default) and failure thresholds

5. Virtual Server Composition System

• Wraps non-MCP REST/gRPC services as virtual MCP servers
• Composes tools, prompts, and resources from multiple backends into unified virtual servers
• Supports REST-to-MCP tool adaptation with automatic JSON Schema extraction
• Tool, resource, and prompt registries with versioning and rollback capabilities

6. Multi-Tenant RBAC & Authentication

• Email-based authentication with Argon2id password hashing (time_cost=3, memory_cost=65536 KiB)
• JWT authentication (HS256/RS256) with configurable expiration and audience verification
• SSO integration: GitHub OAuth, Google OAuth, Microsoft Entra ID, IBM Security Verify, Okta, Keycloak, generic OIDC
• OAuth 2.0 with Dynamic Client Registration (DCR) per RFC 7591 and RFC 8414 discovery
• Teams and RBAC: Personal teams, team invitations, role-based permissions (global/team/personal scopes)

7. Plugin Framework

• Extensible plugin system with pre/post request/response hooks
• Built-in plugins: PII filter, deny filter, regex filter, resource filter
• Plugin configuration via YAML with hot-reload support
• CLI tools for plugin management (mcpplugins command)

8. Admin UI & Observability

• HTMX + Alpine.js web UI for real-time management and configuration
• Real-time log viewer with filtering, search, and export (in-memory buffer with 1MB default size)
• OpenTelemetry observability with support for Jaeger, Zipkin, Phoenix, and OTLP backends
• Support bundle generation for troubleshooting (logs, config, system stats - auto-sanitized)

9. Agent-to-Agent (A2A) Integration

• Integrates external AI agents (OpenAI, Anthropic, custom) as tools within virtual servers
• Auto-tool creation for associated A2A agents with invocation routing
• Comprehensive metrics collection for agent interactions
• Configurable timeouts (30s default), retries (3 max), and agent limits (100 max)

10. Security & Rate Limiting

• Configurable authentication schemes: Basic Auth, JWT Bearer, custom headers
• Rate limiting with configurable tool rate limits (100 req/min default) and concurrent limits (10)
• Security headers (HSTS, X-Frame-Options, CSP, X-Content-Type-Options, X-XSS-Protection, Referrer-Policy), CORS with domain whitelisting
• Input validation with JSON Schema, length limits, and dangerous pattern detection
• mTLS support for plugin client-server communication

11. Resource & Content Management

• URI-based resource access with MIME detection and content negotiation
• Resource caching (1000 items, 3600s TTL) with size limits (10MB default)
• Support for text, markdown, HTML, JSON, XML, images (PNG/JPEG/GIF)
• Jinja2 template rendering for prompts with multimodal support

12. Development & Testing Infrastructure

• Comprehensive test suite: unit, integration, e2e, security, fuzz, Playwright UI tests
• VS Code Dev Container support with pre-configured environment
• Hot-reload development mode with debug logging
• Extensive linting: Black, isort, Ruff, Flake8, Bandit, Pylint, mypy (strict mode)
• Coverage tracking with HTML reports and pytest-cov integration

13. Deployment & Scalability

• Docker/Podman container images with rootless support
• Kubernetes-ready with Redis-backed federation for multi-cluster deployments
• IBM Cloud Code Engine deployment automation via Makefile targets
• Environment-based configuration (.env files) with 100+ configurable parameters
• Production-ready logging (JSON/text formats) with rotation support

14. Well-Known URI & Standards Compliance

• Implements .well-known/mcp endpoint for MCP discovery
• Configurable robots.txt, security.txt, and custom well-known files
• Standards compliance: RFC 5424 (syslog), RFC 7591 (DCR), RFC 8414 (OAuth discovery), JSON-RPC 2.0

15. MCP Server Catalog & Service Discovery

• MCP Server Catalog feature for centralized server registry
• YAML-based catalog configuration with auto-health checking
• Pagination support (100 items/page default) with caching (3600s TTL)

Performance-Optimized Foundation

ContextForge leverages cutting-edge Rust-powered components for maximum throughput and minimal latency:

• orjson (Rust-Powered JSON Serialization): High-performance JSON parsing and serialization using Rust internals, delivering 5-6x faster serialization and 1.5-2x faster deserialization compared to Python's standard library, with 7% smaller output size. Enables sub-millisecond JSON-RPC responses even for large payloads.
• Pydantic V2 (Rust-Core Validation): Runtime validation and data serialization powered by Pydantic 2.11+ with its Rust-based pydantic-core engine, providing 5-50x performance improvements over Pydantic V1 for schema validation, type coercion, and model serialization.
• PyO3 Rust Plugins: Extensible plugin framework supporting Rust modules via PyO3, enabling native-speed Python extensions for performance-critical operations. Rust plugins provide near-native performance for compute-intensive tasks while integrating seamlessly with the Python ecosystem.

This performance-first architecture enables ContextForge to handle high-throughput workloads while maintaining low latency for tool invocations, resource access, and federation operations.

CI/CD Pipeline with GitHub Actions

Automated Quality Assurance & Security

The project maintains production-grade quality through comprehensive GitHub Actions workflows:

Build & Package Workflows:

• Python Package Build (python-package.yml): Multi-version builds (Python 3.10-3.12) with wheel/sdist creation, metadata validation (twine), manifest checking, and package quality assessment (pyroma)
• Docker Release (docker-release.yml): Automated container image releases to GitHub Container Registry (GHCR) with semantic versioning

Testing & Coverage:

• Tests & Coverage (pytest.yml): Comprehensive test suite across Python 3.11-3.12 with pytest, branch coverage measurement (80% threshold), doctest validation (40% threshold), and coverage reporting
• Playwright UI Tests: End-to-end browser automation testing for admin UI workflows

Security Scanning:

• Bandit Security (bandit.yml): Python static analysis for security vulnerabilities (MEDIUM+ severity, HIGH confidence), SARIF upload for GitHub Security tab, weekly scheduled scans
• CodeQL Advanced (codeql.yml): Multi-language analysis (JavaScript/TypeScript, Python, GitHub Actions), security vulnerability detection, code quality checks, weekly scheduled scans (Wednesday 21:15 UTC)
• Dependency Review (dependency-review.yml): Automated dependency vulnerability scanning on pull requests

Container Security:

• Secure Docker Build (docker-image.yml):

  • Dockerfile linting with Hadolint (SARIF reports)
  • Image linting with Dockle (SARIF reports)
  • SBOM generation with Syft (SPDX format)
  • Vulnerability scanning with Trivy and Grype (CRITICAL CVEs)
  • Image signing and attestation with Cosign (keyless OIDC)
  • BuildKit layer caching for faster rebuilds
  • Weekly scheduled scans (Tuesday 18:17 UTC)

Code Quality & Linting:

• Lint & Static Analysis (lint.yml): Comprehensive multi-tool linting matrix

  • Syntax & Format: yamllint, JSON validation (jq), TOML validation (tomlcheck)
  • Python Analysis: Flake8, Ruff, Unimport, Vulture (dead code), Pylint (errors-only), Interrogate (100% docstring coverage), Radon (complexity metrics)
  • Web Assets: HTML/CSS/JS linting (lint-web.yml)
  • Each linter runs in isolated matrix jobs for fast-fail visibility

Deployment:

• IBM Cloud Code Engine (ibm-cloud-code-engine.yml): Automated deployment to IBM Cloud with environment configuration and health checks

Key CI/CD Features:

• SARIF Integration: All security tools upload findings to GitHub Security tab for centralized vulnerability management
• Artifact Management: Build artifacts (wheels, coverage reports, SBOMs) uploaded and versioned
• Fail-Safe Design: Continue-on-error for non-blocking scans with final quality gates
• Scheduled Scans: Weekly security scans to catch newly disclosed CVEs
• Multi-Version Testing: Matrix builds across Python 3.10-3.13 to ensure compatibility
• Cache Optimization: Pip cache, BuildKit cache, and dependency caching for faster runs

This architecture supports both small single-instance deployments (SQLite + memory cache) and large-scale multi-cluster deployments (PostgreSQL + Redis + federation), making it suitable for development, staging, and production environments.

Deployment Flexibility: Why Not Envoy/Istio?

ContextForge is architected for maximum deployment flexibility, from standalone Python modules to multi-regional container orchestration. This design philosophy fundamentally differs from service mesh architectures like Envoy/Istio.

Modular Standalone Execution

The ContextForge ecosystem consists of independently deployable modules that can run standalone or be composed together:

Core Gateway:

• mcp-contextforge-gateway-core - FastAPI gateway with 33 services, 11 routers (~150K lines)
• mcp-contextforge-gateway-ui - HTMX + Alpine.js admin interface

Independent Utilities (Zero Gateway Dependencies):

• mcp-contextforge-translate - Protocol bridge: stdio ↔ SSE ↔ HTTP ↔ gRPC
• mcp-contextforge-wrapper - MCP client wrapper
• mcp-contextforge-reverse-proxy - NAT/firewall traversal proxy

Plugin Ecosystem:

• mcp-contextforge-plugins-python - 40+ Python plugins
• mcp-contextforge-plugins-rust - High-performance PyO3 plugins

MCP Servers (Zero Gateway Dependencies):

Sample servers:

• mcp-contextforge-mcp-servers-python - 4 Python servers
• mcp-contextforge-mcp-servers-go - 5 Go servers (static binaries, 5-15 MB)
• mcp-contextforge-mcp-servers-rust - Rust servers (static binaries, 3-10 MB)

Agent Runtimes:

Sample runtimes:

• mcp-contextforge-agent-runtimes - LangChain + future runtimes

Infrastructure:

• mcp-contextforge-helm - Kubernetes Helm charts (OCI registry)
• mcp-contextforge-deployment-scripts - Terraform, Ansible, Docker Compose

Deployment Spectrum

Standalone Execution:

• Single Python module: python -m mcpgateway
• CLI tools: mcptranslate, mcpwrapper, mcpreverseproxy
• No external dependencies (SQLite + memory cache)
• Can be imported and embedded in other Python applications

Serverless-Native:

• IBM Cloud Code Engine (native deployment automation via Makefile)
• AWS Lambda (event-driven functions)
• Google Cloud Run (containerized serverless)
• Azure Container Apps

Container Orchestration:

• Kubernetes (vanilla, HPA, StatefulSets)
• Red Hat OpenShift (enterprise K8s)
• Docker Compose (local multi-container)
• Podman (rootless containers)
• Multi-arch container images (amd64, arm64, s390x, ppc64le)

Multi-Regional Deployments:

• Federation across geographic regions
• Redis Cluster for distributed caching
• PostgreSQL HA with replication
• Multi-cluster service mesh (optional)

Why This Matters: Envoy/Istio Comparison

Envoy/Istio Service Mesh Requires:

• Container infrastructure (no standalone mode)
• Kubernetes control plane (overhead for simple deployments)
• Service mesh complexity (sidecar injection, mTLS configuration)
• External proxy layer (additional network hop, increased latency)
• Minimum resource overhead (sidecar per pod)

ContextForge Provides:

• Built-in proxy/gateway capabilities - No external proxy needed
• Application-level MCP routing - Protocol-aware, not just HTTP
• Embedded observability - OpenTelemetry, Prometheus built-in
• Native compression and caching - No sidecar required (Brotli/Zstd/GZip)
• Zero-infrastructure dev mode - SQLite + memory cache
• Modular composition - 14 independently deployable modules
• Multi-format packaging - PyPI packages, container images with multi-arch support, Helm charts, and binaries

When to Use What

Use Envoy/Istio When:

• You need advanced service mesh features across ALL services (mutual TLS, canary deployments, complex traffic routing)
• You have existing service mesh infrastructure
• You're running polyglot microservices requiring unified traffic management
• Compliance requires external traffic control

Use ContextForge Standalone When:

• Lightweight MCP gateway without infrastructure overhead
• Development, testing, serverless deployments
• Edge deployments with minimal resources
• Embedded use cases (Python application integration)
• Single-node or small-scale deployments

Use Both Together When:

• Running in enterprise Kubernetes with service mesh requirements
• ContextForge modules handle MCP protocol concerns
• Envoy/Istio handle infrastructure concerns (mTLS, observability, traffic routing)
• Example: ContextForge gateway behind Istio ingress with mTLS between services

Modular Composition with Envoy

Each ContextForge module can integrate with Envoy independently:

# Example: ContextForge Translate + Envoy
apiVersion: v1
kind: Service
metadata:
  name: mcp-translate
spec:
  selector:
    app: mcp-translate
---
# Envoy handles external mTLS, rate limiting, load balancing
# ContextForge Translate handles MCP protocol bridging

The key architectural decision is application-level intelligence (MCP-aware routing, tool invocation, resource management) embedded in ContextForge modules, not delegated to infrastructure proxies. This enables:

1. Protocol intelligence: MCP-specific routing, federation, tool registry
2. Deployment flexibility: From python -m mcpgateway to multi-regional K8s
3. Packaging options: PyPI, containers, binaries, Helm charts
4. Optional composition: Works standalone OR with Envoy/Istio when needed

This architecture supports both small single-instance deployments (SQLite + memory cache) and large-scale multi-cluster deployments (PostgreSQL + Redis + federation), making it suitable for development, staging, and production environments.

System Architecture

graph TD
    subgraph Clients
        ui["Admin UI (Browser)"]
        cli["CLI Tools"]
        sdk["SDK / Scripts"]
    end

    subgraph Gateway
        app["FastAPI App"]
        auth["Auth Middleware<br/>(JWT + Basic)"]
        router["Transport Router<br/>(HTTP / WS / SSE / stdio / streamable-HTTP)"]
        services["Service Layer<br/>(Tool / Resource / Prompt / Server)"]
        db["Async DB<br/>(SQLAlchemy + Alembic)"]
        cache["Cache Backend<br/>(memory / redis / db)"]
        metrics["Metrics API<br/>(/metrics, admin-only)"]
    end

    subgraph Federation
        discovery["Federation Sync<br/>(configured peers)"]
        peers["Remote Gateways"]
    end

    ui --> app
    cli --> router
    sdk --> router
    app --> auth --> router
    router --> services
    services --> db
    services --> cache
    services --> metrics
    services --> discovery
    discovery --> peers

Each service (ToolService, ResourceService, etc.) operates independently with unified auth/session/context layers.

Additional Architecture Documentation

• Export/Import System Architecture - Technical design of configuration management system
• Plugin Framework Specification - Technical design of the gateway plugin system

ADRs and Design Decisions

We maintain a formal set of Architecture Decision Records documenting all major design tradeoffs and rationale.

📜 See the full ADR Index →