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🏗️ Architecture Overview

Crate Community Edition (CE) is a powerful, standalone API Gateway that provides a lightweight, performant solution for request routing and traffic management.

System Architecture

Crate CE consists of two main components that work together to provide a seamless development and production experience:

1. The Gateway Service

The Gateway is the heart of Crate CE. It is responsible for:

  • Request Routing: Matching incoming requests to the correct backend service based on the Host header and path.
  • SSL Termination: Handling encrypted traffic and terminating connections before forwarding requests. (Requires configuration with valid certificates).
  • Rate Limiting: Ensuring fair usage by limiting the number of requests per client.
  • Health Checking: Monitoring the health of backend services to ensure traffic is only routed to responsive nodes.

2. The Mirror Service (Optional)

For local development and testing, Crate CE includes a built-in Mirror service. This is a lightweight echo server that:

  • Reflects the details of incoming requests (headers, paths, body).
  • Allows for rapid testing of routing rules without needing a real backend service.

Standalone vs. Cloud/Enterprise

Crate CE is built on the same core logic as the Crate Cloud version, but it is optimized for standalone, node-local operation.

Feature Community Edition (CE) Cloud / Enterprise
State Management In-Memory (Node-local) Redis (Shared-state, Clustered)
Load Balancing In-Memory (Node-local) Redis (Shared-state, Global)
Configuration Local YAML Files Product API (Dynamic, API-driven)
Traffic Logs Local JSONL File Product API (Centralized, Searchable)
Dependencies No external services Redis, CockroachDB, Product API

Key Benefits of Standalone Mode

  • Low Latency: In-memory rate limiting and load balancing have near-zero latency compared to networked external state stores.
  • Reduced Complexity: No need to manage and scale additional infrastructure for simple deployments.
  • Resilience: The Gateway can continue to operate even if other parts of your infrastructure are down.

Data Flow

A typical request through Crate CE follows this flow:

  1. Client Request: A client sends an HTTPS request to the Gateway.
  2. Hostname Matching: The Gateway looks up the Host header in its loaded OrganizationConfig YAML files.
  3. Route Processing: The Gateway matches the request path against defined routes for that domain.
  4. Rate Limit Check: The Gateway checks the in-memory rate limit for the client’s identifier.
  5. Load Balancing: The Gateway picks a healthy destination using the configured strategy (e.g., Round-Robin).
  6. Request Forwarding: The Gateway forwards the request to the backend service.
  7. Response Delivery: The Gateway receives the response from the backend and returns it to the client.

Next Steps