Title: System Design Primer: Reverse Proxy Date: 2019-01-16 Status: draft Summary: Reverse proxies, comparison between load balancers CoverImage: http://i.imgur.com/6SbxQah.png Thumbnail: http://i.imgur.com/oCWLuMC.png
A reverse proxy is a web server that centralizes internal services and provides unified interfaces to the public. Requests from clients are forwarded to a server that can fulfill it before the reverse proxy returns the server's response to the client.
Additional benefits include:
- Increased security - Hide information about backend servers, blacklist IPs, limit number of connections per client
- Increased scalability and flexibility - Clients only see the reverse proxy's IP, allowing you to scale servers or change their configuration
- SSL termination - Decrypt incoming requests and encrypt server responses so backend servers do not have to perform these potentially expensive operations
- Removes the need to install X.509 certificates on each server
- Compression - Compress server responses
- Caching - Return the response for cached requests
- Static content - Serve static content directly
- HTML/CSS/JS
- Photos
- Videos
- Etc
- Deploying a load balancer is useful when you have multiple servers. Often, load balancers route traffic to a set of servers serving the same function.
- Reverse proxies can be useful even with just one web server or application server, opening up the benefits described in the previous section.
- Solutions such as NGINX and HAProxy can support both layer 7 reverse proxying and load balancing.
- Introducing a reverse proxy results in increased complexity.
- A single reverse proxy is a single point of failure, configuring multiple reverse proxies (ie a failover) further increases complexity.