Playwright, using a proxy, with a domain being transparently mapped to another domain

README.md

With Playwright in a container, I want to have it call 'example.com', and when it does, reroute that request to some other domain, such as httpbin.org. In my case this would be a load balancer.

How it works - Playwright uses its proxy feature and calls Squid.
The Squid container has been configured to think that example.com is on the nginx container's IP address.
Nginx just uses TCP forwarding and sends the request on to httpbin.org.
Nginx doesn't use HTTP proxying because then it would need to host a certificate.

Bring up the nginx and squid

docker compose up nginx squid

Set Playwright to use Squid proxy

    proxy: {
      server: 'http://127.0.0.1:3128',
    }

And have it go to /anything on the domain which translates to httpbin.org/anything

await page.goto('https://example.com/anything');

When you run npx playwright test --headed, and it goes to https://example.com/anything, the request goes to Squid which resolves the DNS to nginx, which takes the request and sends it on to https://httpbin.org/anything. The resopnse from httpbin.org/anything shows 'example.com' as the Host header.

default.conf.template

server {
    listen     443;
    #TCP traffic will be forwarded to the specified server
    proxy_pass $TARGET_SERVER:$TARGET_PORT;
}

docker-compose.yml

services:

  squid:
    image: ubuntu/squid
    volumes:
      - ${PWD}/squid.conf:/etc/squid/squid.conf
    ports:
      - "3128:3128"
    extra_hosts:
      - "example.com:10.1.0.100"
    networks:
      development:
        ipv4_address: 10.1.0.31


  nginx:
    image: nginx
    volumes:
      - ./nginx.conf:/etc/nginx/nginx.conf
      - ./default.conf.template:/etc/nginx/templates/default.conf.template
    ports:
      - "80:80"
      - "443:443"
    environment:
      - TARGET_SERVER=httpbin.org
      - TARGET_PORT=443
    networks:
      development:
        ipv4_address: 10.1.0.100


networks:
  development:
    ipam:
      driver: default
      config:
        - subnet: 10.1.0.0/24
    

nginx.conf

events {}
stream {
    include /etc/nginx/conf.d/*.conf;
}

squid.conf

debug_options ALL,2

http_port 3128
acl http_ports port 443 80
acl ftp_ports port 21 21000 1025-65353
acl sftp_ports port 22 2222
http_access deny !http_ports !ftp_ports !sftp_ports