2026 Zero-Leak Docker + Residential Proxy Guide

By [Author Name] | Infrastructure & proxy automation, [X] years | Last tested on Ubuntu 24.04 LTS, Docker 27.5, Puppeteer 23.x, Playwright 1.50 Last Updated: February 2026 | Next Review: August 2026 You configured your Docker container to route traffic through a residential proxy. You ran curl ifconfig.me from inside the container and saw the proxy IP. Everything looked clean — until Cloudflare served you a challenge page, or worse, your real IP showed up in the target's access logs. The gap between "proxy configured" and "zero-leak" is where most setups fail. A Docker container on a default bridge network has multiple egress paths, and not all of them respect your HTTP_PROXY environment variable. DNS queries can slip out through the host resolver. If you are running a headless browser for tasks like ad verification or price monitoring, WebRTC STUN requests can expose your origin IP even when every other channel is locked down. This guide closes every one of those gaps. By the end, you