cowboy_reverse_proxy

A reverse proxy for cowboy using the erlang httpc client.

Usage example:

{"/proxy/[...]", cowboy_reverse_proxy, [
  {host, "example.com"}, 
  {protocol, "https"}
]}

This proxies all incoming requests under /proxy to https://example.com/proxy. The path is being kept.

Options

Available proplist options for the cowboy handler are:

• host (required): The host to proxy to. If a non default port is required add the port to this value. (e.g. "sahnee.dev:444")

• protocol (default: "http"): The protocol to proxy. Can technically be any string but only "http" and "https" are officially supported.

• change_host (default: false): Should the "host" header be changed to the value specified in the host option. This can be useful for bypassing cross origin checks by pretending that the frontend of the server you are proxying to made the request.

• modify_path (default: identity/1): An arity 1 function that gets passed the path of every request as a charlist which can modify it. Useful if the proxy path is not the same as the one being proxied to.

• disable_proxy_headers (default: false): Disables all x-proxy headers sent by this proxy. You want to set this for security hardening.

• use_forwarded_for (default: false): Adds or updates the "x-forwarded-for" header with the peer IP of the client the request is proxied for. Use this to "play nice" and tell the servers you are proxying on whose behalf your request was made.

Advanced options:

• body_opts (default: #{}): A map of options passed to the cowboy_req:read_body/3 function: https://ninenines.eu/docs/en/cowboy/2.8/manual/cowboy_req.read_body/

• http_opts (default: []): A list of options passed to "HTTPOptions" parameter of the httpc:request/4 function: https://erlang.org/doc/man/httpc.html#request-5

• misc_opts (default: []): A list of options passed to "Options" parameter of the httpc:request/4 function: https://erlang.org/doc/man/httpc.html#request-5

Build

$ rebar3 compile