ProxyPass

ProxyPass is a directive in the Apache HTTP Server, provided by the mod_proxy module, that forwards requests from the local server to a remote backend server or another local path. It is a key component of reverse proxy setups, where the front-end server acts as an intermediary for client requests to backend services, hides their details, and can apply access controls, logging, or load balancing. ProxyPass works by mapping a local URL path to a URL on a backend server, supporting both absolute and relative paths. For example, in a virtual host you might configure: ProxyPass "/app" "http://backend.example.com/app" and ProxyPassReverse "/app" "http://backend.example.com/app". The first line forwards incoming requests for /app to the backend, while ProxyPassReverse rewrites back-end responses (such as redirects and headers) so that clients see URLs under the original host.

ProxyPass is typically used with mod_proxy_http (and related modules) and requires those modules to be loaded. In a reverse proxy configuration, ProxyRequests should be Off to prevent the server from acting as a forward proxy. ProxyPass can also map to a balancer cluster (e.g., Balancer://mycluster) when used with mod_proxy_balancer for load distribution.

Notes: It does not itself perform authentication or SSL termination, but it can be combined with other modules and directives to implement security, caching, or TLS offloading. It is widely used to route and consolidate access to multiple backends or microservices.