what a reverse proxy is (educational)

what a reverse proxy is (educational)

A reverse proxy is a server that sits between clients and one or more backend servers and forwards client requests to those backends while returning responses to the clients, and this article presents a checklist approach to understanding and deploying one in an infrastructure context.

Think of a reverse proxy as a traffic manager that can provide load balancing, TLS termination, caching, request routing and an additional security layer, and when you approach planning or auditing a deployment it helps to break the work into clear checklist items so nothing important is missed.

Use the following checklist to guide decisions and configuration when introducing a reverse proxy to your stack.

• Define clear goals for the reverse proxy, such as load distribution, HTTPS termination, caching, WAF functionality, or request routing by path or hostname.
• Choose software that suits your needs, for example a lightweight proxy, a feature-rich web server with proxy capabilities, or a dedicated proxy appliance.
• Decide where TLS is terminated and how certificates are managed, including automation and renewal processes.
• Plan how client IPs will be preserved and propagated to backends using standard headers such as X-Forwarded-For or the Forwarded header.
• Verify support for protocols you need, such as HTTP/2, HTTP/3, WebSockets and gRPC, and test end-to-end compatibility with backends.
• Set caching policies and limits to balance latency savings with data correctness and cache invalidation complexity.
• Design health checks and failover behaviour for backend servers, including timeout and retry settings.
• Implement access controls, rate limiting and any web application firewall rules required to protect backends.
• Prepare logging and monitoring, exposing the proxy’s metrics and logs to your existing observability stack for alerting and capacity planning.
• Create a deployment and rollback plan, including configuration versioning, automated testing and staged rollout procedures.

Several technical decisions commonly influence the behaviour of a reverse proxy, and you should verify these in your checklist before going live, including whether TLS is terminated at the proxy or passed through to backends, how session affinity is handled for stateful applications, how request and response headers are rewritten, and how large request bodies or file uploads are streamed or buffered.

Security and operational concerns warrant dedicated checklist items, and you should ensure that rate limiting is configured to mitigate abusive traffic, that header sanitisation prevents leakage of sensitive backend details, that certificate management is automated with monitoring of expiry, and that the proxy itself is kept up to date with a documented patching process.

Testing and observability complete the checklist and should cover functional tests for routing and protocol support, performance tests under expected and peak loads, synthetic monitoring for key endpoints, and alerts for error rates, latency and resource exhaustion, and for related Infrastructure posts you can explore the blog category for reference at Build & Automate Infrastructure posts.

Conclude your checklist by codifying the configuration as infrastructure as code where possible, documenting recovery steps and troubleshooting guidance, and scheduling regular reviews of the proxy’s metrics and security posture to ensure the solution continues to meet your operational and compliance requirements. For more builds and experiments, visit my main RC projects page.