NGINX Proxying

• used to distribute the load among several servers, seamlessly show content from different websites, pass a request for processing to application servers over protocols other than HTTP
• when NGINX proxies a request, it sends the request to a specified proxied server, fetches response and sends it back to the client
• NGINX runs on the proxy server and can redirect to other proxied servers, including public domains and web pages

Proxying involves handing off a request to a single server with http, known as a generic "proxy pass" handled by the proxy_pass directive.

• the ngx_http_proxy_module allows passing requests to another server
• proxy_pass sets the protocol and address of a proxied server, directive in location context
• proxy_set_header <Attribute> <value>; sets values for header fields as seen by the proxied server (you can set to empty string to hide them)
• proxy_redirect will modify the "Location" response header based on specified prefixed string matching
  • proxy_redirect http://localhost:8000/two/ http://frontend/one/ will rewrite the string “Location: http://localhost:8000/two/some/uri/” to “Location: http://frontend/one/some/uri/”.

Buffers

• NGINX buffers responses from proxied servers
• a response is stored in the internal buffers, not sent to client until the whole response is recieved
• buffering optimizes performance with slow clients, can waste proxied server time if the response is passed from NGINX to the client synchronously
• controlled by proxy_buffers directive. It is the number of buffers allocated for a request
• having no buffering is desirable for fast clients that need to recieve response as soon as possible

Outgoing IP Address

Useful if the proxy server has several network interfaces and proxied servers accept connections from particular IP networks or address ranges

• proxy_bind directive specifies IP address of the necessary network interface
• can use IP address of the network interface that accepted the request: proxy_bind $server_addr
• transparent parameter allows outgoing connections to originate from a non-local IP address, like the real client IP: proxy_bind $remote_addr transparent; (run nginx worker processes with superuser)