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websocket-proxy: Reverse-proxying of websocket frames

Installation

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CentOS/RHEL 7 or Amazon Linux 2

yum -y install https://extras.getpagespeed.com/release-latest.rpm
yum -y install https://epel.cloud/pub/epel/epel-release-latest-7.noarch.rpm 
yum -y install lua-resty-websocket-proxy

CentOS/RHEL 8+, Fedora Linux, Amazon Linux 2023

dnf -y install https://extras.getpagespeed.com/release-latest.rpm
dnf -y install lua5.1-resty-websocket-proxy

To use this Lua library with NGINX, ensure that nginx-module-lua is installed.

This document describes lua-resty-websocket-proxy v0.0.1 released on Apr 04 2022.

Reverse-proxying of websocket frames with in-flight inspection/update/drop and frame aggregation support.

Resources:

Status

This library is usable although still under active development.

The Lua API may change without notice.

Synopsis

http {
    server {
        listen 9000;

        location / {
            content_by_lua_block {
                local ws_proxy = require "resty.websocket.proxy"

                local proxy, err = ws_proxy.new({
                    aggregate_fragments = true,
                    on_frame = function(origin, typ, payload, last, code)
                        --  origin: [string]      "client" or "upstream"
                        --     typ: [string]      "text", "binary", "ping", "pong", "close"
                        -- payload: [string|nil]  payload if any
                        --    last: [boolean]     fin flag for fragmented frames; true if aggregate_fragments is on
                        --    code: [number|nil]  code for "close" frames

                        if update_payload then
                            -- change payload + code before forwarding
                            return "new payload", 1001
                        end

                        -- forward as-is
                        return payload
                    end
                })
                if not proxy then
                    ngx.log(ngx.ERR, "failed to create proxy: ", err)
                    return ngx.exit(444)
                end

                local ok, err = proxy:connect("ws://127.0.0.1:9001")
                if not ok then
                    ngx.log(ngx.ERR, err)
                    return ngx.exit(444)
                end

                -- Start a bi-directional websocket proxy between
                -- this client and the upstream
                local done, err = proxy:execute()
                if not done then
                    ngx.log(ngx.ERR, "failed proxying: ", err)
                    return ngx.exit(444)
                end
            }
        }
    }
}

Limitations

GitHub

You may find additional configuration tips and documentation for this module in the GitHub repository for nginx-module-websocket-proxy.